Tag Archive | crop rotation

How To Grow Potatoes In 5 Simple Steps

Can we grow new potatoes from old potatoes?

grow potatoes

Yes!

So… those potatoes left in the pantry or the bottom of the refrigerator decided to sprout. Instead of throwing them into the trash or the compost bin, try growing them! You can grow potatoes in the home garden or in large pots, following a few simple guidelines.

Too withered for consumption, but fine for the garden.

We don’t recommend planting potatoes recently purchased from the grocery store because they’ve likely been treated with a sprout inhibitor. After the effect wears off, you’ll see the eyes begin growing. That, though, could take months.

Organic potatoes, if treated with sprout suppressors approved by the National Organic Program, sprout earlier than non-organic potatoes. Inhibitors, such as spearmint, peppermint, and clove oils, must be applied more frequently than chemicals used on traditionally treated potatoes.

Spouting potatoes (like the ‘Yukon Gold’ in photo, top) are still edible, after removing the eyes. Discard moldy and rotting potatoes. But save for the garden the ones with well-developed sprouts and those that have withered beyond the point of palatability.

Carbohydrates stored in the tuber provide energy for the developing shoots. When green leaves begin growing, photosynthesis will sustain the plant.

When can we grow potatoes outside?

Potatoes can tolerate cool soil, but not cold, wet soil or freezing temperatures. I live in USDA plant hardiness zone 7, where we plant early maturing varieties 4-6 weeks before the last spring frost. Gardeners plant mid-season and late varieties after that.

Wait for the soil to warm up to at least 45°F before planting tubers. Long-range weather forecasts might indicate whether it’s safe to plant or prudent to delay.

A garden exposed to full direct sunlight warms up earlier in spring than one in partial sun. Grow potatoes in full sun, but avoid exposing them to searing summer heat. Gardeners living in higher elevations or in cooler summer regions can grow potatoes through the season.

If the weather forecast predicts temperatures below freezing, I’ll mulch the soil with several inches of oak leaves, never in short supply around here. A thick, airy mulch insulates the ground from a sudden drop in temperature. Plants benefit from mulch kept in place all season. Not only does it moderate temperature, suppress weeds, and keep moisture in the ground, but it also prevents disease spores from splashing onto the potato’s leaves. This is easier to do in small garden plots than in larger farming operations.

Emerging foliage can tolerate light frost. It could take a few weeks for growth to show above ground.

Seed Potatoes

For a wider selection of varieties offered to farmers and home gardeners, look for “seed potatoes”. Some garden centers and many seed suppliers stock seed potatoes. They’re not actually seeds, but certified young potatoes almost ready for planting. Although they’re certified disease-free when purchased, plants are susceptible to a few pathogens as they grow.

Favorable conditions and good management practices decrease the likelihood of problems. If you’ve had diseases in your potato crops, don’t save potatoes year to year, but purchase certified potatoes instead. Don’t grow potatoes where they’ve been planted any time in the past 4 years.

Botanically speaking, potatoes are classified as Solanum tuberosum. They belong to the Solanaceae family and call tomatoes, peppers, and eggplants their cousins. Tobacco, petunias, and deadly nightshade, a poisonous weed, also belong to the nightshade family.

Potatoes are native to the cool mountainous regions of South America. In the 1530’s, European explorers gathered them and introduced potatoes to their homeland. Irish immigrants brought them to North America in the early 1700’s. Approximately 4,000 varieties of potatoes have been bred. True seeds, as opposed to seed potatoes, are poisonous when eaten and are used only for breeding purposes.

You can find potatoes with white, yellow, tan, red, blue, and purple skins and flesh. Thin-skinned potatoes, such as ‘Yukon Gold’, ‘Kennebec’, and ‘Red Pontiac’, grow well in the eastern parts of the U.S. The western states suit the thicker-skinned ‘Russet’ and other baking potatoes.

Crop Rotation

One of those good management practices involves rotating our crops. Related plants tend to be susceptible to the same pathogens and insect pests. When growing one crop in the same plot of land year after year, disease spores and insects can build up in that location. That’s why it’s recommended to move all members of a particular plant family to different plots over the next several growing seasons.

For example, if you grew potatoes, tomatoes, peppers, or eggplants in Plot A in any of the last 4 years, move your potatoes and other members of the Solanaceae family to Plot B this year, Plot C next year, and then Plot D the year after that.

Rotate among the various plant families, such as:

brassicas—arugula, broccoli, Brussels sprouts, cabbage, cauliflower, kale, etc., in the Brassicaceae family
cucurbits—cucumber, squash, zucchini, melons, in the Cucurbitaceae family
legumes—peas, beans, in the Fabaceae family
lettuces, in the Asteraceae family
onions, leeks, garlic, in the Amaryllidaceae family
Swiss chard, spinach, beets, in the Amaranthaceae family

Several varieties of potatoes.

How To Grow Potatoes In the Garden

Step 1: The First Cut

Before planting potatoes in the ground, cut them into pieces about 1½” long. Each piece should have 2-3 eyes. Let them sit in the open air for 1-2 days to seal the cut surface. This helps prevent rot in moist soil.

Small potatoes can be planted whole.

Step 2: Prepare the Soil If You Want To Grow Potatoes

Thorough soil preparation serves the immediate purpose as well as plantings in years to come. After improving the soil with generous amounts of drainage materials, you’ll need to add nutrient-rich amendments a few times each year after that.

Not repeatedly disturbing the soil profile retains healthy populations of beneficial microbes. Farmers are increasingly using no-till methods and cover crops to preserve soil structure and prevent erosion of valuable topsoil. Frequent tilling also introduces high levels of oxygen between the particles of soil, so organic matter is broken down too quickly.

Vegetable plants need good drainage, and potatoes are no exception. Loosen the soil at least 12″ deep, breaking up the clods. Potatoes struggle in compacted clay and stony soils; tubers that do form are often misshapen. Potatoes grow very well in raised beds.

Incorporate a few inches of pine fines, soil conditioner, peat moss, and/or coarse sand to improve the tilth (or workability) of the soil. Avoid layering materials in the soil profile. Layers of coarse and fine materials, with differing air pore spaces from one material to another, obstruct water percolating through the soil. This could cause soggy layers that can rot roots. For that reason, I never place a layer of gravel under plantings.

In the top 5″ of loosened soil, mix in compost, leaf mold, or planting mixes. These materials contain a variety of nutrients required by vegetables, and they encourage rapid rooting.

Aged manure and mushroom compost are not recommended for root vegetables.

Soil PH

Potatoes love heavily composted soil. They also require acidic soil, with a pH between 5.0 and 6.0. (Various websites recommend a pH anywhere between 4.8 and 7.0.)

Low pH helps prevent scab, a disfiguring disease of potato skins. Soil pH outside the preferred range for potatoes limits nutrient absorption and might cause nutrient toxicities.

Contact your local agricultural extension agents for information on taking a soil test. They can recommend preferred fertilizers, methods to lower soil pH, and varieties appropriate for your area.

Step 3: Place the Seed Potatoes

In rich, organic soil, simply lay the potato pieces on top of moist, loosened soil or nestle them into the surface. The eyes should face upward. Then mulch over the seed potatoes.

They’ll also grow when planted 2″ deep. Space potatoes 6-12″ apart, depending on variety. Because potato plants grow 2-3′ tall and might sprawl a bit, allow 30-36″ between rows.

Mulch the bed with a few inches of leaf litter, shredded leaves, and pine needles to cover the planted potatoes. It’s important to adequately shade the surface of the ground from sunlight to protect growing tubers from greening…

“Greening”?

Potatoes with green skin needed deeper mulch.

Greening is caused by exposure to light, which, in itself, is not harmful. But the green pigment (chlorophyll) in potatoes is associated with the formation of a toxic glycoalkaloid called solanine.

Never eat green potatoes; if only the skin is green, cut off and discard that part before cooking. Never eat leaves, stems, or the berries that develop on potato plants.

Solanine in potatoes is more concentrated when growing potatoes in high nitrogen soils and in soil that’s compacted or very sandy. Bruised potatoes, those held a long time in storage, and potatoes with large eyes are higher in this toxin. The greener the potato, the higher the level of solanine. This bitter substance is a natural repellent to insects and browsing animals.

Solanine can’t be boiled or cooked away. The level is somewhat lower in foods fried at very high temperatures, but that brings its own problems, described later in this article. I’m not intent on discouraging you from growing or eating potatoes, but moderate consumption of this popular vegetable and proper preparation make it a healthier indulgence.

Symptoms of solanine toxicity include vomiting, diarrhea, slow pulse or breathing, low blood pressure, and abdominal pain. It can cause coma and death in rare instances, so be very careful with green potatoes. If any of the flesh is green after removing the skin, I would discard the potato.

Step 4: Maintenance

Water

Water the garden thoroughly after planting and mulching. If rain is unreliable, water the garden every week, never letting the soil become dry. Provide 1-1½” of water each week if it doesn’t rain.

Avoid wetting the foliage, and water in the morning so the foliage is dry going into the night. This helps cut down on the incidence of disease. Some varieties are resistant to blight, scab, Rhizoctonia, and Verticillium wilt. Those that have not been bred with disease resistance often produce great yields when using good gardening practices.

Hollow Heart and Brown Center

Some large varieties, particularly ‘Atlantic’ (for potato chips) and ‘Yukon Gold’ (a personal favorite), might show hollow heart and/or brown center. These are physiological disorders characterized by a star-shaped cavity and a central area with dead brown tissue, respectively, in the center of the potato or near the ends.

These stress-related conditions often result from inconsistent soil moisture—for example, wet soil after a period of dry soil. In addition, a period of prolonged cold weather during tuber formation can cause brown center. Spacing seed potatoes too far apart and using small seed potatoes (with too few eyes) can be the cause. Low potassium and other nutrient deficiencies can initiate the disorders.

The potato’s skin shows no indication of a problem. Affected potatoes aren’t perfect but are still edible.

Hilling Up

As the plants grow, hill up soil against the stems of the plants. Take soil from another part of the garden, adding a few inches up the stem and about 12″ out from it. This is an option—not necessary—but it should increase the yield.

Like tomatoes, potatoes root along buried stems. As they root, they’ll develop another layer of young potatoes at the ends of the stolons. Hill up around the stems 2 or 3 times during the growing season to maximize the harvest.

An alternative is to start potatoes in a moderately deep trench, reserving excavated soil on the side of the bed. Periodically fill in the trench with amended soil, a few inches at a time.

Fertilizer

Every few weeks, apply a complete fertilizer. The 3 numbers on the package representing nitrogen, phosphorus, and potassium (N-P-K) should be in a ratio of 1:1:1 or 1:2:2. Avoid fertilizers high in nitrogen. An analysis close to 10-10-10 or 5-10-10 is adequate.

Although you could use chemical fertilizers, they tend to damage populations of beneficial microbes. But, until the soil warms up, microbes aren’t sufficiently active to break down the organic components into molecules the plants can absorb. That’s when I use chemical fertilizers, and then switch to organic products when the soil warms.

To help prevent disorders in developing potatoes, it’s recommended to apply smaller concentrations of fertilizer more frequently.

Insect Pests

Colorado potato beetles can be especially bothersome as they consume significant amounts of foliage. Inspect the undersides of the leaves for yellow-orange egg masses and remove them. The beetles have 10 black stripes on their tan wings. Immature larvae are orangish-red with 2 rows of black dots down each side. Bacillus thuringiensis var. tenebrionis, a biological insecticide, kills this beetle.

Aphids might congregate in large numbers on the plants. A brisk spray of cool water from the hose takes care of most of them. Encourage ladybugs, braconid wasps, and green lacewings to populate your garden. For severe infestations, prepare a solution of horticultural oil and spray early in the morning. Apply the solution to the bottoms of the leaves as well. Read the label.

Cutworms feed on sprouts emerging from the ground. Since these C-shaped larvae become moths, treating the potatoes with Bacillus thuringiensis var. kurstaki effectively kills them. Keep in mind that they’ll have to eat some of the foliage in order to ingest the Bt.

Slugs and Deer

A slug.

Slugs reproduce rapidly in moist conditions and where they can hide in crevices during the daytime.

Lay a board on moist ground, and slugs and snails will gather there after feeding through the night. You might notice those silvery slime trails on tender foliage. Early in the morning, take an old knife to the garden and… dispatch them forthwith! Or use organic Sluggo or similar product, which does not contain toxic chemicals. Except to slugs and snails. Read the label.

Although potato foliage is not the favorite choice of warm-blooded animals, deer and others will feed on it when not much else is available.

Other members of the nightshade family also host these pests. Row cover secured over the planting excludes most insects and browsing animals.

Potatoes that sprouted in storage are now growing new plants in 6″ pots. They’ll need protection from hard frost if planted, but I didn’t want to delay planting the deteriorating tubers.

Headings

Page 1: Can we grow new potatoes from old potatoes? (When can we grow potatoes outside?, Seed Potatoes, Crop Rotation), How To Grow Potatoes In the Garden, Step 1: The First Cut, Step 2: Prepare the Soil If You Want To Grow Potatoes (Soil PH), Step 3: Place the Seed Potatoes (“Greening”?), Step 4: Maintenance (Water, Hollow Heart and Brown Center, Hilling Up, Fertilizer, Insect Pests, Slugs and Deer)

Page 2: Step 5: Harvesting!, How To Grow Potatoes In Containers, Grow Potatoes For Their Nutrients (The Power Of the Purples, Potato Skins, Resistant Starch), The Problem With High Heat

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Seedlings For Your Garden: 12 Tips

Jun27

2022

Starting Seedlings For Your Garden

Busy spring! This lengthy article focuses on starting and caring for seedlings and getting them established in the garden. If I’m not working on the seedlings, I’m working in the gardens, creating new beds and expanding those started last fall and winter. Winter weather was delightfully mild to allow planting right through the cold season. The weeds and I have come to an understanding, and in the next article, I’ll tell you how in “Patches for Pollinators”.

Foremost on the agenda has been starting plants to sell at our local Elkin Farmers’ Market. It’s been a challenge this year, keeping plants in good condition with high heat, heavy humidity, and frequent rainstorms. If I had a climate-controlled greenhouse, there might have been fewer losses. But, for the most part, my company, Wellspring Gardens, is producing more seedlings than I can sell at the market.

Some of that overproduction is destined for the vegetable gardens. It will yield small harvests of produce to sell at the market in addition to what’s needed in the kitchen. This is new territory for me, adding produce to the plants offered at the farmers’ market.

I might even consider canning, which I’ve never done…but let’s not get ahead of ourselves. That would be helpful, though, considering the rapidly rising prices at the grocery store. For that reason alone—the impact of rampant inflation on our wallets—it’s wise to learn how to grow at least a few vegetables.

The sun’s path across the sky, Charlotte NC.

Watching how the sun tracks across the sky from month to month reveals good spots for the sun worshipers and areas where leafy greens should thrive in partial sun. This is my first summer in this house. The massive oak trees create shifting shade patterns that cause me to periodically rethink the plans.

So, let’s begin!

12 Tips For Starting Seeds

1. Start with clean materials for seedlings.

Sweet pepper ‘Glow’, started in 9-cell packs.

This calls for packaged seedling mix or fine-grained potting soil. Don’t use “dirt” from the garden, with its pathogens, insects, weed seeds, and worms that disrupt soil structure around tiny roots. In addition to the unknowns lurking in garden soil, its high clay content causes drainage issues in containers.

Soil used previously for potted plants is not a good medium for your seedlings. It’s often depleted of nutrients, might contain pathogens, and the organic matter has partially decomposed. If it’s only one season old, it’s probably safe for potted annuals, when mixed with fresh potting soil, or incorporated into the backfill for that new sourwood tree. Or simply throw it under the shrubs or into the compost pile.

Because seedlings are susceptible to soil-borne diseases, play it safe and start with pasteurized bagged seedling mix or potting soil. This, however, doesn’t guarantee a successful outcome, as many disease spores are air-borne. But we can increase the odds of success by using clean materials.

When reusing cell packs, pots, and flats for seeding, wash them in a 10% bleach solution, and rinse well before proceeding. Don’t smoke around plants, and wash hands thoroughly before working with them. Tobacco and other plants in the nightshade family (Solanaceae, including tomato, pepper, eggplant, and potato) can fall prey to the same disease organisms. Spores can transfer from tobacco products to your hands to the plants.

Pasteurizing Potting Soil

For bagged soil that’s questionable, you can pasteurize it in the oven. Don’t heat soil that contains timed release fertilizers. Use an oven-safe covered pot or baking dish, wet the soil, and heat the oven to 200°F. When the soil registers 140° on a meat thermometer, lower the oven temperature and maintain soil at that temperature for 30 minutes. This kills most pathogens. Wait for it to dry somewhat and to cool thoroughly before using. Various websites recommend different temperature levels from 140° to 300°. At the high end, beneficial microbes are killed off as well.

Let it cool down outdoors. Considering the pervasive “earthy” odor coming from hot soil, you might prefer buying a new bag of seedling mix or accept a small risk with the open bag in the garage.

Another method of pasteurizing (not sterilizing) soil is to place a heat-resistant container of soil in a black plastic bag. Place the bag in a sunny place outdoors on a warm day, and let the sun do the work for you. This is called solarization, and can raise the temperature inside the bag to 140-160°F. To prevent damage to the beneficial microbes, take the temperature, and maintain it at 140° for 30 minutes, opening the bag a bit to prevent overheating.

Most bagged potting soils and seedling mixes already have been heat-treated to eliminate pests. Close the bag securely and store in a cool dark place. The last and only time I pasteurized soil was nearly 50 years ago because that’s what the experts recommended.

2. Grow disease resistant varieties…

While fungicide and bactericide formulations—both organic and conventional—are available, I’d rather grow disease resistant varieties and not rely on spraying. Keep in mind that resistance is not 100% effective, particularly when plants are exposed to stressful weather or cultural conditions.

Certain varieties are more flavorful than others, but all well-grown fruits and vegetables from your own garden taste better than those purchased from grocery stores. Picked when vine-ripened perfect, anything coming from the garden will be superior to what’s found elsewhere except, perhaps, at farmers’ markets and farm stands. Freshly picked produce also has the highest nutrient content.

Digging in the garden is great exercise; proceed slowly at first. Working outside in nature feels good, and self-sufficiency is never amiss. A few steps from the back door gathering a green onion, spinach, dinosaur kale, and a little ripe sweet pepper for the veggie omelet is more rewarding than I can describe. You’ll see!

Those are just a few of the many benefits of growing our own vegetables. Using disease resistant varieties, if available, makes the job so much easier. Many new gardeners gave up after having suffered the disappointment of losing an entire crop to early blight or bacterial leaf spot. And we also have to deal with deer, rabbits, and insects!

Although this article concentrates primarily on edibles, flowering plants also have their own set of disease organisms. Again, look for resistant varieties, grow them in conditions that don’t favor infection, and look for remedies at the garden center.

…Especially Tomato Seedlings

Disease beginning on ‘Rutgers’ tomato.

Tomatoes and peppers, two of the most popular crops for home vegetable gardens, are vulnerable to many diseases. They’re caused by fungal, bacterial, or viral pathogens. In some areas, nematodes also can be a problem. Usually, we can harvest some fruits before disease claims them, but resistant plants last longer in the garden. Plants infected with viruses should be removed and destroyed. For fungal and bacterial pathogens, products at garden centers will help. Always read the labels.

Tomato diseases include Alternaria stem canker, early blight, late blight (Phytophthora; very few varieties are resistant to this one), Fusarium wilt, grey leaf spot, leaf mold, tobacco mosaic virus, tomato mosaic virus, tomato spotted wilt virus, and Verticillium wilt. Catalog listings use initials to indicate disease resistance. For tomatoes, AS, EB, LB, F, GLS, LM, TMV, ToMV, TSWV, and V, respectively, represent those diseases.

Tomatoes are weedy plants and normally produce good crops, despite many organisms that target them. Peppers are susceptible to several races of bacterial leaf spot, and basil to basil downy mildew. Some zinnias are plagued by powdery mildew. Weather conditions, such as high humidity and frequent rain, exacerbate these disease problems.

Most hybrid (or “F1”) tomatoes have some resistance to one or more pathogens, but not to all of them. ‘Big Beef Plus’ is resistant to a wide variety of diseases. ‘Damsel’ and ‘Defiant PhR’ are resistant to late blight. Hybrid seeds carry a higher price than open pollinated varieties due to the cost of research that developed them and the extra steps needed to produce hybrid seeds each year.

It’s so hot out there!

If you live in a hot climate, look for tomato varieties that have been bred to produce better at high temperatures. The pollen in tomatoes and peppers, and others, can die at high temperatures. While these plants are comfortable at 65-80°F, pollen dies above 88°, 90°, or 92°, depending on the cultivar. No pollination = no fruits! A reference to “heat” or to the “south” in the plant’s variety name indicates its higher tolerance for heat.

Researchers are investigating thermo-tolerant genetics in wild tomato species (Solanum pimpinellifolium) and incorporating them in tomato breeding programs.

One trick to preserve viable pollen is lightly shading the plant in the hot afternoon hours. Attach shade fabric—a black woven mesh—to a support over and on the west side of the tomato or pepper plants. This provides a decrease of up to several degrees in hot climates or temporarily during a heat wave. In the photo, above, mesh bags from the grocery store protect fruits from squirrels and sun scald, and lightly shade new flowers and their pollen from high heat.

The young ‘Estiva’ tomato plants (“estiva” refers to summer), a hybrid bred for heat tolerance and great taste, lost most of their diseased bottom leaves in heavy rains, but those little fruits are still growing! I’ll plant them out this weekend, after the temperatures drop well below the 108° heat index value we have now. Recent weather has been in the record-breaking mid- to high 90’s F, with high humidity. Not my favorite conditions to dig in the garden…so I don’t. I was not bred for heat tolerance!

***Update***: ‘Estiva’ tomatoes endured this hot summer and produced fruits past the first fall frosts. I covered them on chilly nights to ripen the last of the fruits. These were among the last tomatoes to succumb to the cold, in mid-November. Autumn 2022

A Few More Tomato Tips

Your best defense against tomato disease, in addition to growing disease resistant varieties, includes these tips:

Stake them. Tall indeterminate types need a 6-8′ tall stake, taller for some.
Space them farther apart, at least 3½-4′.
Thin the vines to 3 or 4 main stems by removing excess suckers.
Remove leaves on the bottom 12″ of the plants after they’ve become established.
Locate them where a breeze blows through the garden. These first 5 tips address increasing air circulation around and through the tomato plants.
Give them lots of direct sun—a minimum of 7 or 8 hours. The more sun they receive, the shorter the window of opportunity for pathogens to germinate on damp leaf surfaces.
Mulch the soil under the plants to prevent disease spores lying dormant in the soil from splashing onto and infecting the foliage. More on Page 4.
Water in the morning to early afternoon so all foliage is dry going into the night. Try to keep the foliage dry at all times and avoid handling wet foliage.
Water established plants heavily (1½”/week) when needed, but avoid giving little sips every day. Young seedlings need more frequent watering until their root systems expand.
Clip off leaves that show early symptoms (yellowing, spotting), and dip your pruners in alcohol when moving from plant to plant.
Don’t smoke near the garden, and wash hands thoroughly before working with plants.
Rotate your crops. Don’t plant a member of the Solanaceae family where any members have grown in the past 3-4 years. There’s more about crop rotation on Page 4.

All plants grown with good soil preparation, good air circulation, proper watering techniques, adequate sun, and appropriate fertilization are less stressed. Less stress equates to lower infection rates.

Growing Heirloom Seedlings

: These “black” heirloom tomatoes are higher in beneficial pigments called anthocyanins, which are powerful antioxidants. ‘Cherokee Purple’ (above) originated near the NC/TN border, and had been grown by the Cherokee for generations before seeds became widely available in the early 1990’s. ‘Black Prince’ (left), is a high-yielding variety, shown before fruits darkened.

Heirloom tomatoes are always in demand because of their exceptionally good flavor. Heirlooms are open pollinated, which means gardeners can save seeds from fully ripened fruits each year for the next season’s garden. Because they’re not F1 hybrids but have been breeding true, for the most part, for many decades, heirlooms retain their traits from one generation to the next.

These varieties, however, don’t have much built-in disease resistance. Nevertheless, I’m growing a few heirlooms, and spacing them 4′ apart for improved air circulation. We’ll see what happens.

Commercially grown tomatoes must be able to survive long distance transportation and handling without damage. They’re picked early, when green or first showing color. Varieties of these tomatoes have skins that normally are tougher.

Heirloom tomatoes have more desirable thinner skins and, therefore, travel poorly. So, you won’t see them in grocery stores unless those stores buy from local farms. Heirloom tomatoes from the grocery store might cost $5.00/lb. or more! So, yes, it is worth growing a couple of heirloom tomato plants in our gardens.

A few prolonged and heavy rainy periods this spring almost wiped out certain tomato varieties, namely ‘Carmello’, ‘Brandywine’, and ‘German Johnson’. I still have a few that show less damage than others. ‘Black Krim’ and ‘Cherokee Purple’ are doing fairly well, although they are heirlooms. Most of the remaining plants will be set in the garden. There’s usually a breeze blowing through the property, and by spacing them appropriately, I should get plenty of fruits.

Basil Downy Mildew

First symptom of BDM: yellow blotches between the main veins.

Although this dreaded disease targets only basil, it hasn’t appeared yet this year. But I’m prepared.

Last year, I grew ‘Rutgers Obsession DMR’ (DMR = Downy Mildew Resistant), an acceptable substitute for our beloved ‘Genovese’ and other susceptible sweet basils. Last year’s ‘Obsession’ did not develop any basil downy mildew (BDM)—not one speck—although wet and humid weather presented a worthy challenge. Other basil varieties in the ground or in pots succumbed to the disease within a week of infection…even young seedlings.

This year, I’m growing ‘Rutgers Obsession DMR’ and also ‘Rutgers Devotion DMR’ outside all summer. In addition, I’m seeding the old favorites, including ‘Genovese’, ‘Italian Large Leaf’, Thai basil ‘Siam Queen’, ‘Marseillais Dwarf’, and ‘Tuscany’, a lettuce-leaf basil. A few non-resistant basil plants will come indoors at night when warranted, as described below. But I’ll stop seeding susceptible varieties, except for a few pots, and concentrate on the resistant ones for the farmers’ market if the disease appears in the neighborhood.

Several other BDM resistant varieties can be purchased as seeds or as started plants.

Avoid High Humidity

Healthy sweet basil, in a pot.

If you want to grow your favorite basil varieties that are not resistant to BDM, there is a way to prevent a total loss.

BDM spores move up from the south on the breeze or on infected plants shipped into the area. The spores don’t overwinter in cold climates. If spores land on a susceptible variety, they need a relative humidity above 80-85% for a couple of hours in order to germinate.

Even during pleasant weather, the relative humidity can reach 90% or higher in the 2-3 hours around dawn. That’s when the temperature is usually the coolest and, therefore, the relative humidity is the highest.

When plants show early symptoms of BDM, remove the affected leaves. Take potted basil plants indoors for the night, every night. Indoor conditions never reach those high humidity levels, so you can still grow your preferred basil varieties successfully with a little effort. Remember to place the plants back outdoors after the sun has been up for a couple of hours.

Follow this regimen during rainy weather, although the plants might need to spend a day or two inside. Find the brightest spot to keep them during their temporary stay indoors. If possible, provide some artificial light. Unless it’s wilting, avoid watering basil indoors. Less sunlight means the plant won’t be photosynthesizing optimally or using much water, and wet soil can initiate root rot.

Headings

Page 1: 1. Start with clean materials for seedlings. (Pasteurizing Potting Soil), 2. Grow disease resistant varieties… (…Especially Tomato Seedlings, It’s so hot out there!, A Few More Tomato Tips, Growing Heirloom Seedlings, Basil Downy Mildew, Avoid High Humidity)

Page 2: 3. Timing is important for seedlings. (The Fall Growing Season, Keeping Records, The Cooperative Extension Service, Starting Seedlings Outdoors, Don’t Start Seedlings Too Early, Cool Season Crops, Extending the Growing Season, Seedlings Transplanted Into Bigger Pots, Bunching Onions, The Brassicas, Brassicas In My Garden, Lettuce), 4. Is the temperature suitable for seedlings? (Miniature Incandescent Lights For Warmth, Water Temperature)

Page 3: 5. Start seedlings in small batches. (My Simple Infrastructure), 6. Seedlings need strong light. (Growing Seedlings Under Shop Lights), 7. Cull the weaklings and anomalies. 8. Prevent damping-off disease from killing your seedlings. (Actinovate), 9. Seedlings and plants need fertilizer. (The Elements, Read the Label)

Page 4: 10. Prepare the soil for your transplants. (Start With Good Drainage, Air Pore Space, Gypsum and Lime, Add Nutrient-Rich Amendments, Bury It), 11. Try succession planting for maximum yield. (Crop Rotation, Mulch), 12. Stop the pests before they ruin your garden. (Slugs and Snails, Larvae of Moths and Butterflies, Spider Mites and Thrips, Deer and Rabbits), Concluding

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Tips For Growing a Tomato Plant

Apr29

A Tomato Plant For Your Garden

Anyone who has grown a tomato plant and experienced sublime sun-ripened perfection understands the joy that awaits those new to this endeavor. But it takes a little skill. Starting with light, I’ll explain the basics here. And be sure to read related posts to get the full picture.

How Much Sun For a Tomato Plant?

‘Cherokee Purple’ tomato.

A tomato plant requires at least 7 hours of direct sun. Sure, many sources of information recommend 6 hours, and you’ll certainly have some success. But, for best performance, give it 7 or 8 hours or more.

Tomatoes produce more flowers in a sunnier location. And their leaves will make more “food” (carbohydrates resulting from photosynthesis) that keeps plants growing and producing. More hours of sun maintains drier foliage for a longer period of time. And drier foliage means fewer problems with disease.

Now if you don’t have a spot that gets 7 hours of sun, but it gets 5, you might be able to get fruits from a cherry tomato plant. Instead of being disappointed with the lower-yielding but yummy heirlooms or the big beefsteaks, try ‘Sun Gold’ or the other cherry tomatoes. ‘San Marzano’ and ‘Juliet’ also are worth considering for five or six hours of sun. Because they are high-yielding, you’ll probably harvest something.

But, in full sun, cherry tomatoes produce so many fruits that you’ll be giving them away by the bowlful. Really…they’ll have produced hundreds of fruits on a tall vine by the end of summer.

A “hand” of cherry tomatoes.

Options

If you have the space, some experimentation might yield promising results. Try growing tomatoes in large pots on the sunny patio, and plant greens where there isn’t enough sun for tomatoes. Or perhaps a corner of the sunny rose garden can be given over to edibles that need full sun, if the soil hasn’t been treated with chemicals.

I don’t often recommend cutting down trees. Removing a silver maple that seeded near the vegetable garden, however, will make the garden more productive, and, if permitted, that’s the way to go. When selecting trees for an average size property, choose small-growing trees and locate them far from gardens requiring full sun. Consider their mature size and where the shade will fall from one season to the next.

More Light For a Tomato Plant

Here are some tricks to coax more production out of your edible plants if the sun exposure is less than ideal:

Plant in as sunny a spot as you have, perhaps near a white or light-colored wall, which will reflect more light toward the tomatoes. Or, using a little resourcefulness, create a reflective wall with tall stakes and white fabric.
Lay repurposed light-colored empty mulch or potting soil bags on the soil, on the sunny side of the plants. Anchor them with stones or bricks. Punch lots of holes in the plastic so the plants will get enough water from rain or irrigation. Don’t allow water to collect for more than a few days or you’ll have trouble with mosquitoes.
Porous synthetic or woven mulches are available from garden supply companies. White mulch helps reflect the light and also keeps soil cooler. Additionally, a source of light from below the plant confuses insect pests and might cause them to take up residence elsewhere.
Use a few stakes instead of one, or a wide trellis, for a tomato plant, tying main stems farther out from the core of the plant. This will get more light onto leaves that otherwise would have been heavily shaded.

Crop Rotation

Zucchini.

If space allows, locate your tomatoes, peppers, potatoes, and eggplants (all members of the nightshade family) where none of them have been grown for the last 3 or 4 years. This crop rotation lessens the likelihood of heavy insect and disease outbreaks from one year to the next. It prevents disease spores and insect larvae from building up in the soil and infecting new foliage.

Tomatoes and other members of the nightshade family (Solanaceae) are affected by certain insects and diseases that generally do not bother other families of vegetables. Cucurbits (zucchini, cucumber, squash) and brassicas (broccoli, kale, cauliflower) have their own problems, as do the other plant families.

Disease Resistance

You’ll notice on seed packets, labels, and in catalog descriptions, a series of capital letters after the cultivar’s name. Those letters are initials for the diseases to which that cultivar is resistant. For example, ‘Big Beef’ tomato has the letters AS, F2, L, N, TMV, and V after its name. They represent the diseases Alternaria stem canker, Fusarium wilt (races 1 and 2), Grey leaf spot, Nematodes (not a disease but a tiny worm), Tobacco mosaic virus, and Verticillium wilt, respectively.

Most hybrids have been bred to withstand some disease pressure. Heirlooms are more susceptible to disease, but the flavor of their fruits is superior to that of many varieties commonly found at garden centers. If you have the space, try growing one or two heirlooms in addition to disease resistant varieties.

(***Update***: In 2019, I grew 2 heirloom tomato plants in large pots, and both succumbed to disease well before the end of the summer. We had an especially wet and humid season, but I knew the odds when I’d bought them. Still, each one produced several dozen fruits before removal.)

Susceptibility to disease varies from one area of the country to another, so you might never see some of the diseases that pop up elsewhere.

Weather plays an important role, too, and there’s nothing we can do about that. Choosing at least one disease resistant tomato plant is wise.

To a certain degree, we can manage the environment and our gardening practices in ways that discourage insects and diseases. I almost always include an heirloom tomato plant in my garden, knowing that it is more vulnerable to disease, but it’s worth the effort.

Disease Prevention For a Tomato Plant

For gardeners with limited garden space, crop rotation is not an option. In that case, consider mulching your plants with coarse, chunky material, such as pine bark mulch. Having a dry surface under the plants, as opposed to a moist surface that can harbor disease organisms, is another line of defense. Those large chunks will dry faster than the surface of clay soil or shredded hardwood mulch. Several inches of seed-free straw or dry oak leaves also work.

Porous landscape fabric is another barrier you can use. This product is available in both biodegradable and synthetic materials.

Using pine mulch or fabric will help keep dormant spores of soil-borne diseases, deposited from previous crops, from splashing up onto the low-growing foliage, infecting new plants. Always remove diseased foliage to the trash. Spores can, of course, be blown in from elsewhere, but it’s always best to exercise that ounce of prevention when we can.

Yes, problems can crop up. But usually there is enough fresh produce harvested from your own back yard to consider the garden a worthwhile project.

Air Circulation and Suckers

Tomato sucker removed.

Air circulation around each plant is another factor in disease prevention. I plant tomatoes 4 feet apart in the garden and permit only 3 or 4 main stems to develop on each one. Some growers limit the number of stems to just 2 and space the plants closer together.

A tomato plant is a weedy thing, and, left to its own devices, will create a tangled twining mess of stems and leaves. That doesn’t mean it won’t produce fruit. However, controlling the growth improves air circulation, which keeps the foliage healthier.

As tomato plants grow, suckers grow from axillary buds in the angle between the leaf and the stem. Those suckers will grow into more main stems if not limited. Simply snip out the suckers that have been selected for removal.

Tie stems to tall, sturdy stakes to lift tall plants off the ground. Removing suckers and staking a tomato plant increases the air circulation around and through the foliage, prolonging the plant’s life.

When the plants have been established for a few weeks, and they’re growing vigorously, remove the bottom leaves to get more air circulating underneath the plants. I keep about 12″ of the stem leaf-free. Keep the foliage as dry as possible and avoid handling wet plants.

When Disease Strikes

‘Rutgers’ tomato infected with disease (Septoria?).

Diseased plants will start losing foliage, generally from the bottom up. Leaves become yellow, spotted, puckered, or crispy brown. Widespread disease requires removal of the plants.

If a disease has just been noticed, though, remove to the trash all spotty, blighted leaves with clippers that have been dipped in a 10% bleach solution before going to the next plant. Disease can spread from plant to plant on infected tools and hands.

Spraying the plants with an appropriate remedy might save the plants. Several copper-, bicarbonate-, and microbe-based fungicides are available for organic growers.

Prevent the deadly tobacco mosaic virus from infecting tomatoes and peppers by never smoking near the vegetable garden, and by washing hands thoroughly before working there. Tobacco is related to tomatoes and peppers, and disease spores might be present in the product.

Occasionally we see tomato plants with leaves at the top all twisted and contorted. Sometimes they’re discolored as well. This can result from the application of herbicides, if not on your property, then from a few houses away. The chemical is carried on the breeze, and it takes minute quantities to affect tomatoes. Either cut the plants back to healthy foliage or replace with new transplants. Check also for leafhoppers and aphids inside curled leaves.

Sun Scald

Sun scald on sweet peppers.

On Peppers

Strong sun hitting the fruits on very hot afternoons can cause sun scald. Keeping enough leaf cover will protect the fruits. Patches of sun scald are the parts of the fruit that were perpendicular to the hottest rays of the sun.

Don’t thin pepper plants; they’re especially vulnerable to sun scald. These fruits (photo, above) from a young and sparsely-leaved ‘Lemon Dream’ pepper were not adequately shaded. But the good parts don’t have to go to waste. Simply remove the affected parts.

Tomatoes Exposed To Sun

‘Cherokee Purple’ tomatoes and basil.

I prefer 3 or 4 stems on a tomato plant instead of 2; there are more leaves to lessen the sun’s intensity without entirely shading the fruits.

The flavor is more intense in some varieties (such as ‘Cherokee Purple’, ‘Black Krim’, and other “black” tomatoes) if the fruits are exposed to some direct sunlight. Morning sun is more gentle than hot afternoon sun. But on hot days, exposed tomatoes can get sun scald. Pick those tomatoes, remove the mushy parts affected by sun scald, and eat them right away, before they start rotting.

Sunlight gives fruits a richer color, increasing levels of anthocyanins. What are they? Anthocyanins, the blue and red pigments in fruits and vegetables, are powerful antioxidants, which help fight inflammation and play an important part in cancer prevention.

When you consider how much effort is required to support large amounts of ripening fruit on a mature tomato plant, it seems rational that 3 or 4 leafy stems will be able to produce a lot more “food” (carbohydrates from photosynthesis) for the developing fruits. This will help the fruits achieve full size and, more importantly, full flavor.

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Headings

Page 1: It’s Time To Plant Tomatoes!, How Much Sun For a Tomato Plant? (Options), More Light For a Tomato Plant, Crop Rotation, Disease Resistance, Disease Prevention For a Tomato Plant (Air Circulation and Suckers, When Disease Strikes), and Sun Scald (On Peppers, Tomatoes Exposed To Sun)

Page 2: Time to Plant!, Plant Tomatoes Deeper, Trichomes, Stake or Cage a Tomato Plant?, And Water, and Deer

Pages: 1 2

Soil Prep 101 For Your Vegetable Garden

Apr25

Cool season vegetables and greens.

Finding the Perfect Spot for Your Vegetable Garden

For the purpose of this post, I’ll assume that your vegetable garden will be flush with the surrounding lawn, rather than in a raised bed. However, sound horticultural principles apply to either method. Locate the garden where it gets lots of direct sunlight, and avoid low areas that collect water after heavy rain. Place it close to a source of water.

Now that you’ve found the perfect spot for your vegetable garden, you’re ready for Soil Prep 101. The types of crops you plant in any season are weather-dependent, so make sure weather patterns in your location suit the peppers, basil, kale, or cauliflower.

Although this article concentrates on preparing beds for vegetable gardens, the principles apply to other plants as well, including new shrub borders and flower gardens for pollinators. Page 2 of this article has tips for improving the soil’s tilth, or workability, for most garden projects.

Prerequisites for this class: “How to Prepare the Soil: An Introduction” and “Yes, But Is It Sunny In the Winter?”

Swiss chard in a raised vegetable garden

Swiss chard in a raised bed.

Depending on your level of affinity for precise measurement, you can use either a measuring tape or simple paces to mark the dimensions of your garden. Gardeners who want to indulge in culinary experimentation by growing a wide variety of crops might regret not having made the vegetable garden large enough from the outset. Consider the possibility of expansion in the future.

How Much Sun Does the Vegetable Garden Need?

There is no substitute for sunlight. Without at least 6 hours of direct sun, the results will be disappointing. Anything less than that will reduce and delay the harvest.

Indirect, dappled, and filtered light don’t really count. In fact, during most of the growing season, fruiting plants perform so much better with 7 or 8 hours of sun, minimum! There are other types of crops that can be grown in less than full sun, including leafy greens (lettuce, arugula) and a few herbs (cilantro, parsley).

Layout

Tomato.

Someone out there is asking, “Do I run the rows (the long axes) east-to-west or south-to-north?” Good question! If your plans include growing several tomato plants and maybe some pole beans on a trellis, and you prefer one long plot that is accessible from both sides, I recommend east-to-west.

Long-term plants (tomatoes, peppers, etc.) will continue to get good sunlight all season. Spaced properly, they won’t cast as much shade on each other, especially as fall approaches and the sun sinks lower in the sky. But, if your garden receives sun all day, it won’t make much difference to main season crops.

Cool season crops, grown from fall through early spring, however, will get more sun when planted east-to-west. They’ll face the sun all day even though the days are short.

Taller plants should be planted on the north side of any plot (northern hemisphere), so they don’t shade smaller plants nearby. Some varieties of staked indeterminate tomatoes can grow 8′ tall!

lettuce basket, a portable vegetable garden

Lettuce growing in a basket.

On properties where spatial considerations are limited, do what you can to provide enough direct sun to those crops you can’t live without. Your crops might not be lined up in neat rows, but rather planted individually in a sunny corner over here and another by the back gate. Doesn’t matter. Do what works for you!

Container-grown crops, such as this lettuce basket (photo, above), can be moved around as conditions change.

Multiple Vegetable Garden Beds

With ample space, a series of garden beds can be laid out in a grid. When deciding where the plants will go, always keep in mind that you want to prevent tall plants from shading short plants, with few exceptions. Using straight pathways makes maneuvering the wheelbarrow and equipment easier.

Crops that prefer cooler, part-shade conditions as the weather warms can be planted between the taller plants or in the partial shade they cast. Those include late spring lettuces, arugula, cilantro, and spinach.

Savoy cabbage.

Having several plots allows for crop rotation, planting one family of plants in Plot A this year, in Plot B next year, and so on. This helps prevent the soil from being severely depleted of certain micronutrients and from allowing populations of insects and diseases to build up.

The nightshade family (Solanaceae: tomato, pepper, eggplant, potato), the cucurbits (Cucurbitaceae: cucumber, summer squash, zucchini, melon, pumpkin), and the brassicas (Brassicaceae: broccoli, cabbage, cauliflower, kale, Brussels sprouts) are groups of plants that benefit from being rotated every 4 or more years.

To clarify, one member of a family (tomato, for example) should not be planted where any member of that family (tomato, pepper, eggplant, potato) has grown in the past few years.

This is a good reason to keep a record describing where you plant each crop every year, as well as documenting successes and losses. Knowing the family names that crops belong to also helps with crop rotation.

Seed Or Transplant?

Don’t go overboard if this is your first attempt. You’re not obligated to germinate every pack of seeds you bought. There’s always next season. Most seeds will remain viable for a few years if kept dry and cool.

Starting out with young tomato, pepper, or slow-growing parsley transplants might be more practical than growing them from seed, even though it is more expensive. You’ll find them at garden centers, farmers’ markets, and local hardware stores, and the growers often have good suggestions for cultivation.

If you’re late getting the vegetable garden going, transplants will save you several weeks of growing time. You can always supplement with fast sprouting varieties of seeds, such as those mentioned in the next section.

Starting plants from seed is a welcome challenge to many and is a source of fascination for children—and for adults, too. Don’t laugh, but, for me, it’s a thrill when the catalogs start showing up in the mailbox. I would never discourage you from exploring this facet of gardening. And, of course, there are so many excellent varieties available from seed that never show up in retail stores as transplants.

Seedlings For Vegetable Gardens Need Sun

Seedlings of fruiting crops need at least 6-8 hours of direct sunlight for strong growth. Use clean pots, pasteurized seed starting mix, and a waterproof tray. Provide the proper temperature for germination.

If you don’t have very sunny windows or a greenhouse, consider starting seeds under shop lights with daylight tubes. I use 4′ long fixtures that hold 2 tubes each. Seedlings growing very close to the tubes—only a few inches away—grow strong stems and roots.

Lettuces, arugula, and other leafy greens tolerate fewer hours of sun, although they appreciate full sun during the cooler months.

Avoid starting seeds too early in the season. This could result in leggy, weak plants that might not perform up to par in the garden.

Broccoli ‘Happy Rich’ and Arugula ‘Astro’ seeded into cell packs (late winter, 2022).

Seeding Directly Into the Garden

Some crops grow easily from seed sown directly into the vegetable garden. Peas and beans, for example, and radishes, beets, and carrots are just a few species that can be planted right into prepared ground. Dinosaur kale, mustard spinach, mesclun, leaf lettuce mixes, zucchini, spinach, and cucumbers are more crops that can be directly seeded.

Read all the information on the packet, paying special attention to when to start and how deeply to sow the seeds. Although these crops germinate readily, gardeners must still watch out for pests, both above and below ground, and turns in the weather.

Spacing the Plants

It’s important to calculate how much square footage each of your plants requires, or at least to get a rough idea. On graph paper, map the proposed garden to scale. Use the plants’ spacing recommendations found on the label or the seed packet for the amount of space needed.

With a 1/4″ grid, each square can represent 6″ or 12″ of garden space. The diagram is optional, but it can help in future years when considering crop rotation.

It’s better to have more than enough room rather than not enough; plants don’t respond well to crowding. The seemingly large gaps between the major crops can be interplanted with “ephemerals”—those plants that grow quickly and are harvested before the majors achieve full size. Examples include radishes and lettuce between tomato plants, or green onions and beets between autumn-grown Brussels sprouts.

If It Looks Like This…

Clay soil shrinks as it dries, creating surface cracking.

Soil that dries as hard as a brick is impossible to work with. You can thoroughly water the area the day before or start digging a day or two after a good rain. Avoid digging or walking in the garden when the soil is wet. This compresses the soil, squeezing out tiny channels of air space that are critical for healthy root growth.

Sandy soil that drains too fast should be amended with copious amounts of organic matter. Bagged topsoil is also available, but quality varies widely. The tiny clay particles in clay loam help hold water and nutrients in the soil.

In a large vegetable garden, plan for pathways every 4′ or 5′, and restrict foot traffic to those areas. Use pavers, flagstones, pine bark, or even that old pile of bricks for the pathways. You can get very creative with stonework, and your garden can be the neighborhood show-stopper, but don’t lay out the stones until the end of the soil prep process.

Let’s begin! Please turn the page…

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Headings

Page 1: Finding the Perfect Spot for Your Vegetable Garden, How Much Sun Does the Vegetable Garden Need?, Layout, Multiple Vegetable Garden Beds, Seed Or Transplant? (Seedlings For Vegetable Gardens Need Sun, Seeding Directly Into the Garden), Spacing the Plants, and If It Looks Like This…

Page 2: Remove Sod, Tilth, Soil Prep (The First Dig: Loosen the Clay, The Second Dig: Add Drainage Materials, Organic Matter vs. “Organic”, The Third Dig: Add Organic Matter), Fertilizers, Rake Smooth and Pave, Agricultural Extension and Soil Tests (To Lime Or Not to Lime, and What is pH?)

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