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Garden Advice, Tomatoes

Success with Heirloom Tomatoes

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Heirloom tomatoes are the superstars of the vegetable garden world. They have endearing stories, gorgeous colors, unique shapes, and a flavor beyond compare. Unfortunately, all that flavor and charm comes with a cost. Heirloom tomatoes can be tricky to grow. Many heirlooms lack resistance to fungal and bacterial diseases and have thin skin that splits and cracks easily.

Despite this, we love them and wouldn’t trade them for all the hybrids in the world. They’re too good to resist. That’s why we’ve put together a list of management techniques to help ensure you have success with heirloom tomatoes. 

Protect the Foliage of Heirloom Tomatoes

Many common tomato diseases such as late blight, Alternaria (early blight), Botrytis, and leaf mold, thrive and spread in moist conditions. These fungal diseases produce spores that spread to tomato foliage through wind and water. 

In much of the Southeast, where we have hot, humid summers these diseases are prevalent. Thankfully, there are a few ways to shelter your heirloom tomatoes by protecting their foliage. 

Mulch

One easy way to protect your foliage is with a thick layer of mulch. This prevents soil splash-back onto the tomato’s foliage even during heavy rain. Plus, mulch helps keep the soil moist and prevents weeds.

You don’t need anything fancy. Straw, grass clippings, old leaves, and wood chips all work. For extra weed suppression, place your mulch over a layer of cardboard or newspaper.

In cooler climates, you may need to wait until the soil has fully warmed to apply mulch. Mulching too early can prevent soil warming and reduce early growth. 

Hoophouses

While not available to everyone, hoop houses are one of the best ways to prevent these wind and water-borne diseases. They keep the foliage dry all season and help block wind-borne spores.

Keep in mind that most heirloom varieties are large, indeterminate tomatoes. You’ll need a tall tunnel and a good trellising system.

Two Granny Cantrell’s German Red/ Pink Heirloom Tomatoes on the plant
Granny Cantrell’s German Red/ Pink Heirloom Tomatoes

Use Drip Irrigation, Hand Watering, or Soaker Hoses for Heirloom Tomatoes

Watering methods like drip irrigation or soaker hoses are preferable to overhead watering for heirloom tomatoes. These methods water the base of the plant, keep the foliage dry, and prevent soil splash-back.

If you only have a few plants and these methods aren’t accessible, watering the base of the plant by hand with a hose or watering can is also effective. Avoid using a hard spray which could splash soil onto the leaves.

Space Heirloom Tomatoes Generously

Improving air circulation can greatly reduce disease pressure in tomato plants. While some growers may plant tomatoes as close as one foot, we recommend planting heirlooms at least 2 feet apart in rows 60 inches apart. 

Trellis and Prune Heirloom Tomatoes

Proper pruning and trellising are other key ways to improve airflow and reduce disease pressure. Most heirloom tomatoes are vigorous, indeterminate plants that require sturdy trellises and more frequent pruning. 

Good trellis options include large homemade cages, the Florida weave method, tall stakes, or string systems in hoop houses.

Several common trellising methods are easiest when you prune the plants to a single leader. Pruning to remove suckers also allows more airflow and can encourage good production. 

Learn more about proper pruning here. 

Two Old German Tomatoes on a plate with some slices
Old German Tomatoes

Learn to Identify Common Diseases

Learning to spot common diseases can help you catch problems quickly and take the appropriate steps. If you buy in plants, it may also help you spot signs of disease before you bring it into your garden.

Cornell University has an excellent Tomato Diagnostic Key for identifying diseases. 

If your tomato has a fungal disease like late blight, removing and destroying affected foliage and plants can help slow the spread.

Some growers, particularly commercial growers may also consider using organic fungicides. Like any treatment, they have downsides and should be carefully researched and applied. 

Johnny’s Selected Seeds has a handy chart of organic treatments for pest and disease issues. 

Learn to Spot Nutritional Deficiencies

The issue with nutritional issues is twofold. First many nutrient issues are easy to mistake for disease issues. Before you go spraying fungicide, make sure that the yellowing you’re seeing isn’t just a nutrient deficiency.

The second issue is that nutrient deficiencies stress the plant which can make it more susceptible to disease in the future. Just like you have a stronger immune system when you eat well and get enough sleep, your plant will fight off diseases better when it’s well cared for and nourished. 

Here are common nutrient deficiencies we see in all plants and how to correct them.

Manage Water Carefully

Heirloom tomatoes thrive with consistently moist, but not waterlogged soil. Their thin skin means that large fluctuations in moisture can lead to splitting.

Too little water can also cause issues like blossom end rot. While this disease is caused by a lack of calcium, often the root cause is a lack of water. When the soil is too dry, the plant can’t take up enough calcium, even if it is present in the soil in sufficient quantities.

Overwatering can also dilute the flavor of tomatoes and contribute to disease issues. 

When determining whether you need to water, dig down a couple of inches and feel the soil. It should be moist but not so wet you can squeeze water out of it. 

Purchasing a cheap moisture meter can simplify this process and help remove any doubts about when to water.

Rotate Crops by Family

Many diseases that plague heirloom tomatoes are soil-borne, so proper rotation is critical. We recommend rotating your crops on a four-year cycle. For commercial growers, adding a year in cover crops is also a good idea. 

When rotating crops, do so by family, not just species. For example, don’t rotate just tomatoes. Rotate the nightshade or Solanaceae family including tomatoes, peppers, tomatillos, ground cherries, eggplants, and potatoes.

Abraham Lincoln (Early Abe Lincoln) Heirloom Tomatoes spilling out of a basket
Abraham Lincoln (Early Abe Lincoln) Tomato

Select a Variety Wisely

Each heirloom variety we carry has its own unique set of strengths and weaknesses. A few carry resistance to specific diseases. You’ll find their disease resistance listed in parentheses after the variety name. 

For example, the Abraham Lincoln (Early Abe Lincoln) Tomato has (ab, asc) next to its name. This indicates that it’s resistant to Alternaria (early blight) and Alternaria stem canker. 

See our full key to tomato disease tolerance.

Note that many heirloom tomatoes have not been extensively tested for disease tolerance either in the laboratory or in extensive field trials. The absence of disease resistance information in the variety description does not imply a lack of resistance. 

You can also consider heirloom cherry and paste tomatoes. These usually display more disease resistance than large, slicing tomatoes.

If all else fails, we carry many disease-resistant, open-pollinated varieties. While they may not be considered heirlooms yet, they still have delicious flavor. By saving seed from one of these varieties, you can help create a legacy for one of these newer varieties. 

Garden Advice

Beginner’s Guide to Growing Melons

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Melons are one joy of the summer garden. They’re sweet, juicy, and aromatic, but they can be a little tricky to grow. In this guide, we’ll cover everything you need to know to have success growing melons or muskmelons (Cucumis melo var. reticulatus). 

Muskmelons include green-fleshed and orange-fleshed melons and are often confused with cantaloupes. Cantaloupes are muskmelons, but not all muskmelons are cantaloupes. We only carry one true cantaloupe, Noir des Carmes.

We have a separate post on growing watermelons (Citrullus lanatus), which are a different species with slightly different needs.

Choosing a Variety

Melon diseases aren’t a significant issue for many growers, but they can be a problem for some. If your garden has a history of melon diseases like Alternaria leaf spot, rust, powdery mildew, downy mildew, and Fusarium wilt. It’s best to stick with disease-resistant varieties. 

Thankfully, there are many good options. Here are a few of our disease resistant melons and what they’re resistant to:

Preparing the Soil for Growing Melons

A good melon harvest starts with good soil. These tender fruits are picky about their growing conditions.

First, get a soil test and ensure the pH of your soil is about 7, but no lower than 6. Melons will cannot thrive in soil that’s too acidic and won’t produce well.

Loose, warm, well-drained sandy loam is ideal for melons. If you have clay soil, you will need to work in a good deal of organic matter. Melons will fail in peat, muck, or heavy clay. No matter what your soil looks like, it’s best to add nutrient-rich finished compost before planting. 

If your soil isn’t ideal, consider Pike Muskmelon, which was bred for growing in unirrigated clay soil. Pike produces 3 pound fruits on unirrigated clay or 7 pound fruits on good irrigated soil. 

When to Plant Melons?

Muskmelons are extremely sensitive to temperature and have no frost tolerance. Wait to plant melons outdoors until all danger of frost has passed and soil temperatures have reached 70°F. When starting seeds indoors, sow your melons about 2 to 4 weeks before your last frost date. 

Timing is key when planting melons. Seedling exposure to cold early in a plant’s life can cause melons to fail to set fruit later in the season.

Depending on your growing season and the variety you select, you may be able to plant multiple successions of melons. For example, growers in most of the Southeast can get multiple successions of a fast-growing melon like Delicious 51 PMR Muskmelon, which matures in just 77 days.

Melon Seedlings
This photo shows a very young melon seedling in the top left and an older melon seedling at right.

Direct Sow or Transplant?

You can direct sow or transplant melons into your garden, but each method has a few benefits and drawbacks. 

No matter which method you choose, you want to water your seeds carefully. While they should remain consistently moist, over-watering can cause melon seeds to rot. 

Direct Sowing Melons

Direct sowing melons is less work and may be easier on the plants. Melons have very sensitive root systems that don’t tolerate disturbance, which makes transplanting challenging. However, direct sown seedlings are more susceptible to slug and other pest pressure. 

As you must wait to sow until the soil is warm, they may also take longer to produce a harvest. However, you can speed the process a bit by sprouting your seeds before sowing. Sprout the seeds in moist towels in plastic bags. Check them each day, keeping the towel damp. Sow them in the garden before the root reaches the length of the seed.

Using row cover over your melon beds until the plants begin to flower can help eliminate pest issues and protect them from wind.

When direct sowing, plant seeds 1/2 to 3/4 inches deep 1 to 2 inches apart in rows 5 to 6 inches apart. Later, when the seedlings have developed true leaves, thin them to 12 to 18 inches apart, selecting week seedlings for thinning. No one enjoys thinning, but crowded melons produce poorly. 

Transplanting Melons

Melons are incredibly delicate to transplant, so for must people we recommend sticking to direct sowing. However, transplanting has the benefit of providing an earlier harvest when done successfully. Transplanting seedlings rather than direct sowing can also help reduce seedling loss from slug and pest pressure. 

As they have sensitive root systems, sow your melons in pots, not in flats. Biodegradable pots like newspaper pots are a good option. Sow two to three seeds per pot about 1/2 inch deep. If all three in a pot come up, use scissors to trim off the weaker two.

Keep the pots warm, using a seedling heat mat if possible. Melon seeds germinate best when the temperature is 85 to 90°F. After germination, maintain your seedlings at 75° F or higher.

Hardening Off

Melons are delicate, so it’s important to harden off your transplants. Start by setting them outdoors in indirect sunlight for just a couple of hours. Gradually increase their sun exposure and time outdoors over a couple of weeks. 

Transplanting Outdoors

Wait for ideal conditions to transplant your melons. They are more likely to suffer from transplant shock on windy or chilly days. Again, the soil temperature should be at least 70°F. Water your seedlings the day before you transplant and again about one hour before transplanting. 

Transplant your melons 12 to 18 inches apart in rows 5 to 6 feet apart. Melons typically have long stems by the time they’re ready for transplanting. To help them grow well, gently bury this delicate stem. This will encourage rooting. 

Keep a few seedlings set aside in pots, to fill in any gaps if some of your transplants fail. Melon growing on a vine

Caring for Melons

Once you’ve successfully transplanted your melons, caring for them is fairly straightforward. However, there are a few key steps you want to take throughout the season to ensure a good harvest. 

Watering

Melons require consistent watering through flowering and early fruit set for good production. Keep the soil moist, but not waterlogged. Generally, melons will need about 1 to 2 inches of water per week, depending on the temperatures, wind conditions, and cloud cover. 

Water your melons in the morning. Use a drip hose, soaker hose, irrigation or water at the base of the vine to avoid splashing water on the leaves which can contribute to disease issues. Water deeply about three times per week, depending on the rain. 

Mulch 

Mulch is great for blocking weeds and adding organic matter to the soil, but it can also keep the soil cool. Wait for hot weather to mulch around melons to ensure the soil is warm. Then mulch heavily, especially under developing fruit. 

Pest and Wildlife Issues

Unfortunately, there are several pests and animals that may go after your melon plants. Thankfully, there are some surefire ways to deal with them. 

Early in the season, slugs will feed on the young seedlings. You can deter slugs by temporarily pulling mulch alway from plants and removing slug hiding places. You can also manage their populations by placing homemade beer traps. Fill shallow containers with beer and place them near your plants. The slugs will get in and drown. 

Cucumber beetles are also a major pest of melons and may introduce bacterial wilt to your crop. Proper crop rotation is key to managing cucumber beetle issues. Row cover can also be a good way to exclude the beetles, but must be removed during flowering to ensure good pollination. Amaranth planted nearby also makes a good trap crop. Check out our full post on managing cucumber beetles. 

Cornell University bred the Trifecta Muskmelon for striped cucumber beetle resistance. 

Mealybugs, whiteflies, and aphids can also attack melon plants, but we mostly see this in greenhouse settings. Use a fairly strong spray setting on your hose to blast these pests off the plants. Some people also have luck with soap sprays. However, some melon foliage is sensitive to soap sprays. Try it on a few leaves, before spraying the entire plant. 

Humans aren’t the only animals attracted to sweet melons. It’s likely that your melons will need some protection from animals like groundhogs, raccoons, deer, and other wildlife, particularly during dry seasons! We’ve even had customers report coyotes eating their melons during a drought. Use secure fencing around your garden and melon patch to keep out unwanted dinner guests. 

Harvesting Melons

Ripe melons usually have a telltale sweet aroma. Depending on the variety, you’ll also notice an ivory-yellow coloring. When fully ripe, most melons easily slip from the vine when you put pressure at the base of the stem with your thumb.

Pile of Edisto 47 Muskmelons with the tops one sliced in half to show an orange center
Edisto 47 Muskmelon

Seed Saving 

If you’re planning to save seed from your favorite melon variety, isolate melons by a minimum of 1/8 mile for home use, or 1/2 to 1 mile for pure seed. While you could save seed from a single plant, we recommend saving from 5 to 10 plants to preserve genetic diversity.

You can harvest seed from fully ripe melons that you’ve harvested for the table. However, to get the highest quantity of viable seeds, leave the melons on the vines until they’re over-ripe, about 20 days past your typical harvest time. 

Cut your melon in half and scoop out the seeds. Viable seeds should be firm and plump. Rinse the seeds in a colander, removing the pulp.

Lay seeds out to dry on a tea towel, paper towel, or old screen. When they’re dry enough for storage, you’ll be able to cleanly snap them in half with your fingers. If seeds bend rather than break, they need to be dried longer.

Move fully dry seeds to airtight containers and store them somewhere cool and dark. 

Garden Advice

Cucumber Beetles: Management & Prevention

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Spring is full of hope. It’s tough to think about pests as we’re dreaming of the season to come, but spring is a good time to prepare for common garden pests like cucumber beetles. Learning to identify, prevent, and treat cucumber beetles can help ensure you have a productive season. 

What are Cucumber Beetles?

When people say “cucumber beetle” they’re often referring to more than one species. Here in the Southeast, we typically see striped cucumber beetles (Acalymma vittatum) and spotted cucumber beetles (Diabrotica undecimpunctata). 

In other parts of North America, you may find other beetles that fall into the cucumber beetle category like western striped cucumber beetle (Acalymma trivittatum).

Adult striped cucumber beetles feature a dark head, dark antennae, and yellow back, typically with three distinct black stripes running the length. They are about 1/4 inch long. They feed on vegetables in the cucurbit family, including zucchini, cucumbers, yellow squash, pumpkins, watermelons, and winter squash.

Adult spotted cucumber beetles feature a dark head, dark antennae, greenish yellow backs with six black spots. They are about 1/4 inch long. In their adult form, these beetles may feed on cucurbits like cucumbers and squash along with other crops like corn, beans, cotton, and soybeans 

Besides the physical damage from feeding, cucumber beetles are also vectors for several plant diseases, including squash mosaic virus, cucumber mosaic virus, bacterial wilt, and Fusarium wilt.

Striped Cucumber Beetles on a damaged leaf
Striped Cucumber Beetles by Whitney Cranshaw, Colorado State University / © Bugwood.org

Cucumber Beetle Life Cycle

Both species of cucumber beetle overwinter as adults. They often remain in plant debris in or near the garden. Depending on your location, they leave their hibernation sites in mid-April to June as the temperatures rise. 

The adults feed on seedlings and can kill the plants. They lay their eggs near the base of cucurbit host plants. When their larvae hatch, they feed on the plants’ roots. 

The larvae grow and emerge from the soil as adults between July and September. They continue to feed on plants as adults before finding places to overwinter before cold temperatures set in.

Striped Cucumber Beetles in a Squash Blossom
D. Gordon E. Robertson, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

Signs of Cucumber Beetles

Often gardeners will find the cucumber beetles on their plants. They feed on the stems, leaves, flowers, and fruit, often near the soil. Besides finding adult beetles on the plants, there are a few telltale signs that your garden may have a cucumber beetle problem.

You may notice plants wilting, particularly at the cotelydon stage on young plants. At this stage, large amounts of beetles may also completely defoliate or kill the plants.

On large plants, they create holes in the flowers and leaves. Large infestations may girdle plant stems, weakening or killing the plant. Infested plants may also be more susceptible to lodging in high winds. Cucumber beetles will also feed on the fruit, leaving scars and pockmarks on the surface.

You may also notice disease like bacterial wilt, Fusarium wilt, squash mosaic virus, or cucumber mosaic virus killing your plants. Cucumber beetles may spread these diseases.

Spotted Cucumber Beetle eating a leaf
Matthew T Rader, https://matthewtrader.com, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

How to Prevent Cucumber Beetles

Prevention is the best treatment! While there is no way to guarantee a cucumber-beetle-free garden, there are a few ways you can deter them and reduce their impact.

  • Provide habitat for predatory insects and animals. Researchers have found lower numbers of cucumber beetles in fields with higher populations of wolf spiders and carabid beetles. Encouraging these beneficial insects and other wildlife, like songbirds and toads which feed on the beetles, can help reduce their numbers.
  • If you have a severe infestation, follow a strict fall clean-up. As the adult beetles must overwinter, you can kill them in the fall. Thoroughly clean up any gardens infested with beetles. Destroy plant material and till the garden to exposure them to the cold temperatures.
  • Rotate your crops by family. Cucumber beetles often overwinter right in the garden. Practice crop rotation to avoid planting cucurbits into beds with overwintering populations.
  • Transplant your cucumbers and other cucurbits rather than direct sowing. This will protect new seedlings from cucumber beetle damage.
  • Plant late. If cucumber beetles are regularly a problem on your young plants, sowing or transplanting late may help. Cucumber beetles are most tempted in spring but young, weak seedlings. Waiting to plant until summer can reduce the damage to seedlings.
  • Plant trap crops 3 to 8 feet from your main crop. Certain crops like Hubbard squash are highly attractive to cucumber beetles. Plant them to lure the beetles away from your other crops. When they’re heavily infested, you can burn them to knock back cucumber beetle populations.
  • Try companion planting. Some gardeners have luck deterring cucumber beetles with companion plants. Recommended companion plants include nasturtiums, radishes, marigolds, and catnip.
  • Plant under row cover. Row cover is useful for excluding cucumber beetles from the plants. Just remember to remove it when the plants flower to allow for pollination. 

How to Treat Cucumber Beetles

While prevention is best, if you notice you have cucumber beetles this season, there are a few steps you can take. 

The first is to physically remove the beetles. Handpicking is tough with cucumber beetles, but if you only have a few plants, it may be worth it. Some gardeners have luck with rubbing petroleum jelly on the fingertips of their gloves to help them grab these little insects. 

A slightly easier solution is to use a handheld vacuum to suck up the beetles before dumping them into a container of soapy water.

Yellow sticky traps are another popular way to kill cucumber beetles. Keep in mind these traps can also capture pollinators and other beneficial insects visiting the plants. 

There are few chemical controls available (organic or otherwise). Cucurbits are sensitive, making them tough to treat in this way. One organic solution some gardeners use is neem oil.