Beginner Tips for Growing Plumper Heirloom Tomatoes

One of the easier vegetables to grow

heirloom tomato harvest

The Spruce / Autumn Wood

Heirloom tomatoes are annual plants that have not been crossbred or hybridized for at least 40 years. They are open-pollinated, meaning the seeds will produce plants identical to the parent plant. Growing heirloom tomatoes with saved seeds means you will grow the same tomatoes the next year. Like the many hybrids, heirlooms can be easy to grow; the plants are fast-growing when planted in the spring, but they need 60 to 80 days or more to produce ripe fruit. Keep in mind tomato plants are toxic to pets.

Common Name Heirloom tomato, open-pollinated tomato
Botanical Name Solanum lycopersicum
Family Solanaceae
Plant Type Annual, fruit
Size 5-8 ft. tall
Sun Exposure Full sun
Soil Type Loamy, well-drained
Soil pH Acidic
Bloom Time Summer
Flower Color Yellow
Hardiness Zones 1-13 (USDA)
Native Area South America
Toxicity  Toxic to pets

How to Plant Heirloom Tomato Plants

When to Plant

Tomatoes are best planted in spring (after the threat of frost has passed) as transplanted seedlings or small plants bought from a garden center. If you live in an area with a long growing season, you might have success in direct seeding heirloom tomatoes in the garden, provided you start them early enough.

Selecting a Planting Site

Hybrid and heirloom tomatoes share the same needs when it comes to selecting a planting site. Choose a sunny site with good, well-draining soil. Avoid planting tomatoes in a spot where you already grew plants in the same family, such as peppers or eggplant, because the tomato plants can easily catch any diseases already in the soil.

Spacing, Depth, and Support

Depending on whether they are early or main-season varieties, you should space your heirloom tomatoes between 2 and 3 feet apart. The soil should reach the first set of leaves—setting deeply like this will strengthen the support for these tall-growing plants. Heirloom tomatoes may need tall cages and trellis systems because the plants can become large and robust.

Heirloom Tomato Plant Care

Light

When it comes to sunlight, heirloom tomatoes are one of the hungriest plants out there, along with plants like sunflowers or corn. They need full, direct, unfiltered sunlight all day long. Pay attention to any shadows cast by neighboring trees or buildings when you plan your tomato patch.

Soil

Healthy soil is critical for thriving heirloom tomato plants. They will yield the greatest harvest in rich, slightly acidic (pH 6.0-6.8), loamy soil that allows roots to penetrate deeply. If your soil is heavy clay, use raised beds or container culture. Add compost, leaf mold, or manure up to fifty percent to blend with the native garden soil.

Water

Keeping your tomatoes well-watered is a must, especially once they set fruit. Watering deeply will encourage deep root systems. Assuming you did a good job preparing the soil, drainage should be excellent, so keep an eye on the moisture level and never let plants dry out. Allowing the soil to vacillate between moist and dry causes problems in fruit development, including cracking and blossom end rot. Use drip irrigation to further limit airborne diseases like blight.

Temperature and Humidity

Heirloom tomatoes need warm temperatures to grow. Planting them too early won't give you earlier fruits; wait until night temperatures are at least 60 degrees Fahrenheit before planting outdoors. Humid conditions don't typically bother heirloom tomatoes.

Fertilizer

Heirloom tomatoes are heavy feeders and need regular fertilizing to bloom and fruit. Organic and chemical-balanced all-purpose fertilizers are both acceptable and a matter of personal preference.

unripe heirloom tomatoes
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heirloom tomato ready for harvest
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checking an heirloom tomato for harvesting
The Spruce / Autumn Wood
Heirloom Tomato Plants
Fabio Pagani/Getty Images

Types of Heirloom Tomatoes

There are hundreds of varieties of heirloom tomatoes, and the cultivar names are as colorful as the fruits themselves.

  • Brandywine is a gateway variety for many new to heirloom tomato gardening. The giant pinkish-red ruffled fruits, tender skin, and juicy complex flavor might remind you of a piece of Willy Wonka chewing gum. They have sweet, followed by tangy and spicy, followed by savory and umami flavors, all in one magnificent bite.
  • Black Krim tomatoes originated from Krim, Russia, and quickly gained a wide following with their sweet, robust flavor and handsome maroon fruits.
  • Aunt Ruby's German Green tomatoes stay green until harvest, which might fool hungry squirrels but not your tastebuds. These large beefsteak tomatoes are the perfect blend of sweet and tangy.

Heirloom Tomatoes vs. Hybrid Tomatoes

Heirloom tomatoes and hybrid tomatoes look similar (heirlooms may be less symmetrical or spherical than hybrids) and have the same growing requirements. However, you cannot save seeds from hybrids and expect them to grow true-to-type. Check your plant or seed packet labels if you wish to save seeds.

Brandywine Tomatoes
Posinote/Getty Images
Black Krim Tomatoes
Campbell Downie/Getty Images
Aunt Ruby's German Green Tomato
cristina.sanvito/Flickr/CC BY 2.0

Harvesting Heirloom Tomatoes

Heirloom tomatoes are ready to be picked just before their color begins to peak. Leaving them on the vine too long encourages cracking. Tomatoes that stay green upon ripening can be a little tricky to judge; usually, the color shifts from flat mint green to bright chartreuse or streaky green. The fruits will also soften as they approach their peak.

heirloom tomato harvest
The Spruce / Autumn Wood 
heirloom tomato harvest
The Spruce / Autumn Wood 

How to Grow Heirloom Tomatoes in Pots

If you have space limitations or prefer a plant you can move around to take advantage of the best growing environment, consider growing heirloom tomatoes in a pot. Use a large 12- to 16-inch pot for younger plants or an extra-large 24-inch pot for taller plants. You'll need the large size pots so you can nestle the plant in a deep hole to encourage sturdy, healthy root systems. Heirloom tomatoes growing in containers will need more frequent watering and fertilization than those growing in the ground. Soil in pots tends to dry out fast, especially since tomatoes require between 6 to 8 hours of sun a day, so be sure to check for water needs daily. Fertilize every two weeks with an all-purpose 10-10-10 fertilizer. For the amount to use, read the product label instructions.

Pruning

Pruning heirloom tomatoes can increase plant productivity, improve air circulation in the garden, and provide cuttings for propagation. Remove suckers at the plant base to direct energy to produce fewer but larger fruits. Prune side shoots that appear between the stem and branches, as well. Heirloom tomatoes grow quite large and need staking for support. By reducing the number of fruiting branches down to four or five with pruning, your plants will be manageable, and individual fruits will be larger.

Propagating Heirloom Tomatoes

Tomato cuttings root readily. Take these easy steps with the longer suckers that you prune.

  1. Choose suckers that are at least 6 inches long. Cut them using a clean garden snipper.
  2. Remove the lower leaves of the sucker, but leave two leaves at the top.
  3. Plant one end of the sucker in either a small pot of rich potting soil or root it in a small glass of water (replace the water if it becomes cloudy or dirty).
  4. Water the small pot of soil regularly if it is dry to the touch.
  5. Place the cuttings in bright, but indirect light (it won't tolerate full sun yet)
  6. The suckers will form roots within a week or two. As soon as the roots are secure (if the seedling resists a slight tug), transplant the plant to its permanent home.

How to Grow Heirloom Tomatoes From Seed

Heirloom tomatoes are easy to grow from seed and it's a great way to get a jump start on the season. Use moist, sterile potting soil mix, and sprinkle a few seeds so they are about 1/4 inch deep into the dirt. Cover the seeds with the mix so they are secure in the dirt. Put the pots in a warm spot with bright, indirect light or under grow lights. Germination takes place in about a week if temperatures are between 70 and 75 degrees Fahrenheit.

Potting and Repotting

Younger tomato plants can start out in 1-gallon or large pots, but if you see the plant is getting too tall for the container, it is probably time for repotting it into a larger pot. For the best results, use large plastic or fiberglass pots with drainage holes because they won't dry out as quickly as other materials. To avoid repotting, place a taller, supported tomato plant in a 5-gallon bucket with added drainage holes on the bottom. Use premium potting soil when potting and repotting tomatoes.

Common Pests and Plant Diseases

Pest and disease resistance vary between types of heirloom tomatoes. Typical pests that tomatoes attract include tomato hornworms, aphids, and flea beetles.

Heirloom tomatoes are more prone to fungal diseases and bacterial infections, such as so it's best to keep the foliage dry and off the ground by caging to avoid leaf diseases. Humid weather can also cause early and late blight, which you may be able to spot if the plant's leaves turn yellow.

FAQ
  • Do heirloom tomatoes taste better than standard tomatoes?

    Standard hybrid tomatoes are bred primarily for growing performance rather than flavor. But heirloom tomatoes are grown to have thinner skin, juicier flesh, and better flavor than most hybrid varieties.

  • Can I grow heirloom tomatoes hydroponically?

    Tomatoes, including heirloom types, can grow successfully in hydroponic environments. You can even try setting up an indoor hydroponic garden.

  • What are good companion plants for heirloom tomatoes?

    Tomatoes are frequently grown alongside basil as it is an excellent natural fly repellant, and chives and mint are thought to improve flavor. Potatoes, however, can also suffer from blight, so don't plant them in the same space.

  • Are heirloom tomatoes rare?

    There may be some types of rare heirloom tomatoes, but not all heirloom tomatoes are rare. If you want to try heirloom tomatoes before growing your own, visit a farmer's market or farm stand to find them because the selection may be better than at a standard grocery store.

Article Sources
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  1. Tomato Plant. ASPCA.