Once you've had a ‘Cherokee Purple' tomato sandwich, making one with any other tomato is like skipping the salt and pepper—it just ain't right. Along the same lines, snack on a ‘Black Cherry' tomato fresh from your garden and you'll find yourself constantly counting to see how many more you have left on the vine. It's the over-the-top flavor of these and other heirloom tomatoes that makes us want to grow them . Heirlooms come in all sizes and colors—red, yellow, black, pink, orange, and green. They're not always perfectly round like the ones at your local grocery store, but you won't care one bit once you taste them. (Keep in mind that while the fruit is edible, the leaves, roots, and stems of this nightshade plant are toxic to pets and mildly toxic to children .)
Cindy Martin loves heirlooms. She and her husband, George, own The Tasteful Garden , which specializes in kitchen-garden plants. Each year, this mail-order nursery in Chulafinnee, Alabama, grows and ships thousands of heirloom tomato plants to loyal customers. We asked Cindy to share some of their best tips and advice.
What Is An Heirloom Tomato?
Most horticulturists classify a tomato as "heirloom" only if it is open-pollinated, which means you can save its seeds and pass them down from generation to generation, Cindy explains. These tomatoes stay true to type because, unlike hybrids, they aren't the result of crossbreeding, where a particular cross has to be duplicated to get the same flavor and size. ‘Green Zebra,' a hybrid, is often considered an heirloom but is a result of recent breeding.
"I define an heirloom tomato a little differently," Cindy says. "To me, an heirloom is most any tomato that has not been bred for mass production or large-scale farming. I consider any tomato grown exclusively for its taste, quality of fruit, unique size, or colorful flesh to be an heirloom." Some of these tomatoes have names as colorful as their fruit: ‘Mortgage Lifter,' ‘Arkansas Traveler,' ‘Yellow Taxi,' ‘German Johnson,' ‘Boxcar Willie,' ‘Black Krim,' and ‘Mountain Princess,' just to name a few.
|Common Name||Heirloom tomato|
|Botanical Name||Solanum lycopersicum|
|Plant Type||Vegetable / Fruit|
|Mature Size||3-10 ft. tall, 1-4 ft. wide|
|Soil Type||Well-drained but moist clay, loam, or sand|
|Soil pH||Mildly acidic (6.2-6.8)|
|Hardiness Zones||10-11 (USDA), grown as an annual in other climates|
|Native Area||South America|
|Toxicity||Stems, leaves, and roots toxic to pets , mildly toxic to people|
Heirloom Tomato Care
An heirloom's needs are simple: lots of sun (at least six hours a day) plus rich soil, mulch, regular water, and a trellis, stake, or cage on which to grow. Cindy likes to remind folks that heirloom types come from a time before disease resistance was crossbred into plants.
Instead, most older tomato types have a natural resistance that comes from being grown continually for so many years. "That doesn't mean an heirloom will survive a whole summer free from our Southern blight," she says. "But if you feed it well and add compost and mulch, your tomato will grow just fine and will likely have a strong, healthy root system.
"Many popular heirlooms are from Germany or Russia, and the conditions they prefer are generally cooler than our Southern summers," Cindy continues. "This makes mulching, as well as having good composted soil, very important so the plant is fooled into thinking that the temperature is cooler."
Plant your heirloom tomatoes in full sun, or at least six hours of direct sunlight a day. Some experts recommend eight hours. There's one caveat: Many gardeners start heirloom tomatoes by seed indoors. If that's the case, harden off your seedlings by gradually increasing their time outdoors. Place your transplants in a sheltered spot in bright, indirect light, slowly adding an hour or two of outdoor time a day. Transplant your tomatoes once they are acclimated to full sun.
Tomato plants perform best in mildly acidic, fertile, moderately moist soil. They can grow in average garden soil, even clay, as long as the soil is well-drained. Have your soil tested before the growing season and add the recommended amendments , especially lime if your soil is too acidic. If your soil is poor in organic matter, mix in compost when you plant. Besides providing nutrients, the compost will help conserve moisture.
Because tomatoes do best with consistent moisture, add 2-3 inches of bark mulch, straw, or shredded leaves around your plants. Water tomatoes regularly, especially in sunny, hot weather. Stick your finger in the dirt and water if the top inch of the soil feels dry. Regular watering will help prevent your tomatoes from cracking, splitting, or developing blossom-end rot, which are discussed in more detail below.
Temperature And Humidity
Tomatoes are a warm-season vegetable, so plant after all danger of frost has passed. Tomato plants grow best when it is 70 to 80 degrees Fahrenheit during the day. The plants won't grow much or set fruit if nighttime temperatures drop below 55 degrees Fahrenheit. At the same time, it's best to get your tomatoes in the ground early if you live in the South. Hot days above 85 degrees can prevent fruit from setting, often putting your harvest on pause until temperatures drop again.
Gardeners in the Coastal South (USDA Zone 9) may choose to plant one tomato crop in late winter for an early summer harvest and one crop in late summer for a fall harvest. In the Tropical South, tomatoes are often grown as a fall and winter crop.
A dry climate can cause plants to dry out quickly and necessitate more frequent watering. Very high humidity, on the other hand, interferes with pollination.
Tomatoes are heavy feeders that benefit from fertilization. The best approach is to have your soil tested so you can receive recommendations specific to your garden. If you don't get your soil tested, you can choose a fertilizer formulated for tomatoes and other vegetables. These fertilizers typically have a lower nitrogen level, as too much nitrogen causes plants to produce lots of leafy, green growth instead of fruit. Commercial tomato fertilizers usually contain calcium as well, which helps prevent blossom-end rot.
Fertilize when first transplanting your tomatoes, mixing the fertilizer well into the soil according to the directions on the label. When the first fruits appear, side-dress the plants with more fertilizer (usually 2-3 Tbsp. per plant). Some gardeners continue fertilizing every four to six weeks during the growing season, but this is weather-dependent—don't fertilize your plants during a heat wave.
Types Of Heirloom Tomatoes
Part of the fun of growing heirloom tomatoes is that they come in a rainbow of colors and a multitude of shapes and sizes. Here are a few of the most popular heirloom tomato varieties:
- 'Amish Paste': Red, plum-shaped tomatoes popular for sauces and canning
- 'Black Cherry': Round, dusky brown cherry tomato with complex yet sweet flavor
- 'Black Krim': Medium, very dark maroon tomato with green shoulders, bold flavor
- 'Brandywine': Large, ridged, red or pink beefsteak tomatoes with incredible and full flavor
- 'Cherokee Purple': Lobed or round large tomato, with greenish-brown or purple-pink skin, deep red flesh, and intense, sweet flavor
'German Johnson': Looks like a smaller 'Brandywine' tomato, with deep, acidic flavor
- 'Mortgage Lifter': Large to huge pink-red beefsteak tomato with sweet flavor
- 'San Marzano': Well-known Italian variety with sweet flavor, used for sauces and canning
'Yellow Pear': Pear-shaped, small, and prolific with a sweet, mild flavor
Pruning Heirloom Tomatoes
Pruning tomatoes improves airflow and encourages your plants to focus on producing more and bigger fruit. There are two types of tomato plants: determinate tomatoes, which mature at a certain point and stop growing and producing fruit, and indeterminate tomatoes, which grow continuously until the end of the season. Determinate heirloom varieties are typically bush tomatoes that were bred to produce in a short growing season in colder climates. Determinate tomatoes do not need to be pruned, as it would reduce the amount of fruit produced.
Most popular heirloom tomatoes are indeterminate and will grow wildly throughout the summer. Follow these guidelines for pruning indeterminate tomatoes:
- Once your plant begins to mature and flower or fruit, remove the suckers. The suckers will be growing out of the "V" between the main stem and branches. Pinch off the suckers with your fingers or use a sterile pair of hand pruners—with a couple of exceptions listed below.
- Some gardeners like to grow multi-stemmed plants while still keeping their tomatoes from becoming wild and overgrown. If you'd like a multi-stemmed plant, don't pinch off the sucker just below the first set of flowers or fruit. That sucker will eventually grow into a large, fruit-bearing stem.
- Leaves help shade tomatoes from sunscald, so you may want to retain suckers that are covering the fruit. Pinch off the end of those suckers to keep them from growing, but leave a few leaves behind to provide shade.
- Remove any branches that are growing on the ground or hanging close to the ground. Overburdened branches can be tied to a trellis or cage for support.
Propagating Heirloom Tomatoes
Heirloom tomato plants are incredibly easy to propagate. As many gardeners know from experience, planting a tomato "deep"—that is, burying the lower part of the stem underground—will cause it to form new roots. The same is true of sections of stem. When you're pruning your plant, save a few healthy stems and remove all but the top two leaves from each one. Stick each stem in a pot filled with rich potting soil and water well. Set the pot in indirect light and keep the soil moist. Once a good root system has formed, you can reacclimate the plants to stronger light and plant them in the garden.
How To Grow Heirloom Tomatoes From Seed
When it comes to heirloom tomatoes, seed catalogs offer a cornucopia of choices far beyond what you'll find in the garden center. Peruse those catalogs in winter and order early, as tomatoes should be started six weeks before your last frost date. Follow these steps to grow tomatoes from seed:
- Fill a seed tray or small pots with a lightweight seed-starting mix.
- Press seeds 1/4 inch deep and lightly cover with the seed-starting mix. Some gardeners choose to place two or three seeds in each cell or pot, as a few may not germinate.
- Water well. Place a clear plastic dome or plastic wrap over the pots and set in a warm, sunny window. Tomatoes germinate best at 75-85 degrees (you can use a seedling heat mat under the pots if you keep your house cooler).
- Keep the pots moist and watch for seeds to germinate in about a week. Remove the dome or plastic wrap once the seedlings sprout to create good airflow and reduce the likelihood of disease.
- After the plants have developed the first true set of leaves, thin pots with multiple plants by pulling out the weakest seedlings.
- Continue watering your plants indoors until all danger of frost has passed. If your plants are growing in small cells, transplant them into 4-inch pots once the root system begins to outgrow the available space.
- Now begin to introduce your plants to the outdoors, starting with a sheltered spot for an hour or two in the morning and gradually increasing the amount of light exposure and time outdoors until you are ready to plant.
Potting And Repotting Heirloom Tomatoes
Heirloom tomatoes can be grown successfully in a pot if you give the root system adequate space. Choose at least an 18-inch diameter pot for determinate or bush tomatoes. You can grow indeterminate tomatoes in a pot that is 24 inches or larger. Use high-quality potting soil for tomatoes and make sure the pot has adequate drainage. Add support like a tomato cage, trellis, or stakes.
Potted tomato plants need more frequent watering to keep from drying out. If you find yourself watering several times a day to keep the soil moist, it may be time to repot in a larger container. The soil should not be constantly saturated or soggy; instead, check the top inch of soil and water if dry. To conserve moisture, you can add an inch of mulch around your tomato plants. Placing a saucer under each pot will allow plants to continue absorbing moisture throughout the day.
Common Pests & Plant Diseases
Unfortunately, heirloom tomatoes can be harmed by all sorts of diseases. Crop rotation is key: Don't plant tomatoes in the same spot every year, and if you have a diseased tomato plant, don't plant there again for at least three years. Remove weeds from the area, as they can harbor both diseases and the pests that spread them. Get your soil tested and add lime if it is too acidic to help slow down the spread of disease. Here are some of the most common tomato diseases:
- Bacterial wilt: Soil-borne bacteria fill up stems during hot and humid weather, causing your green plant to rapidly wilt. If you cut an infected stem crosswise, it will look brown inside. Pull and dispose of plants in a plastic bag—don't put them in your compost pile.
- Early blight: Fungi cause brown lesions on the leaves starting at the bottom of the plant. The leaves may begin to yellow around the lesions. Fruit can develop leathery black spots that enlarge into a bull's eye. Trim off and dispose of infected leaves and fruit. For severely infected plants, apply a fungicide.
- Late blight: Lesions from this water-mold pathogen can appear on any part of the plant. Dark, water-soaked spots appear on leaves or shiny brown or olive lesions appear on fruit. White mold can eventually appear on the leaves around infected areas. Pull and dispose of diseased plants.
- Southern blight: The first sign of attack by this soil-borne fungus is a brown lesion on the stem close to the soil line. White patches may appear on the lesion. If the stem is girdled, the entire plant will wilt. Remove and dispose of infected plants quickly. You can try protecting healthy plants with a fungicide or neem oil, but the disease is difficult to control.
- Fusarium wilt: This fungus causes lower leaves of a plant to droop or wilt. Leaves begin to turn yellow and eventually die. The stem appears brown inside. Pull and dispose of diseased plants.
- Tomato spotted wilt virus: This virus is spread by tiny insects called thrips that hang out in weeds around your garden. Plants can be stunted and leaves will develop bronze or dark spots. The fruit can develop yellow spots or darker spots and never ripen. Pull and dispose of diseased plants and spray healthy plants with neem oil or insecticidal soap.
- Tobacco mosaic virus: Leaves become mottled and deformed, often shoestring-like. Pull and dispose of diseased plants. Weed the area and work to control pests like thrips and whiteflies.
- Septoria leaf spot: Caused by a fungus, you'll first notice small dark circular spots with a light center on the leaves. Leaves eventually turn yellow and fall off. Remove and dispose of diseased foliage and improve air circulation around plants where possible. Spray plants repeatedly with fungicide to keep in check.
- Anthracnose fruit rot: Anthracnose fungi cause depressions on tomatoes that begin to develop a black center. The indentations continue growing over time, with spores eventually emerging from the infected area. Harvest fruits frequently to reduce the spread.
Tomatoes are also susceptible to damage from a wide variety of pests. Here are a few to watch out for:
- Caterpillars can attack fruit (tomato fruitworm, tobacco budworm) or chew up leaves (cabbage looper, hornworm) or stems (cutworm). Pick off larger caterpillars and drop them into a can of soapy water. For small caterpillars, Bt or insecticidal soap can be used as controls.
- Beetles can cause pinhole-sized holes in leaves (flea beetles) or significant defoliation (blister beetle, Colorado potato beetle). In many cases, you can keep the population under control by handpicking larger beetles or planting trap crops like radishes for flea beetles. Do not touch blister beetles (identifiable by a long, thin body) as they can irritate the skin. Wear gloves and knock them off with a stick.
- Sap-sucking insects can attack leaves (aphids, whiteflies, thrips) or fruit (stinkbugs). Remove these pests with a good spray of water. If a plant is severely infested, use neem oil or insecticidal soap to discourage insects. Remove any weeds that could be harboring these insects.
Common Problems With Tomatoes
Heirloom tomatoes aren't just affected by disease—issues related to weather or soil conditions can lead to deformed fruit or unusual-looking foliage:
- Blossom-end rot: Fruits develop an ugly brown, often flattened bottom due to calcium deficiency. Though a lack of calcium in the soil can cause this condition, it's often the result of fluctuations in moisture. Make certain that your soil is at the optimal pH before planting tomatoes. Fertilize with calcium nitrate if needed and keep soil consistently moist.
- Cracking and catfacing : Cracking and catfacing (scarring on the bottom of fruit) are also the result of inconsistent moisture. Tomatoes can grow rapidly after a heavy rain and crack. Water regularly during dry spells to prevent it. Extremely cold or hot weather may also cause cracking.
- Sunscald: White or grayish spots develop on exposed sides of the fruit during hot, sunny weather. This condition is most common on plants that have lost a significant amount of foliage. Controlling disease, encouraging new growth, and using shade cloth over exposed tomatoes can help prevent this problem.
- Leaf roll: While rolled-up leaves can be a sign of disease, sometimes it's a matter of needing more moisture. Water if needed, and know that this symptom doesn't necessarily harm your plant.
- Herbicide injury: Tomato plants can be injured by drifting weed killers. If your leaves start to yellow right at the stem, this may have been caused by herbicide. Plants can also look distorted while remaining green.