I’ll be the first to tell you how much I love hybrid tomatoes, created in labs to help growers produce these delicious fruits in an ever-changing climate, fight disease, and ward off pests. However, I’m also a sucker for the old-timey look and flavor of heirloom tomatoes. Nothing compares to these beauties on a Caprese salad with basil fresh from the garden and local mozzarella cheese.
But what makes them so different, and why do some growers consider them special and valuable? This article will explore all of that.
Let’s discuss how to plant, grow, and care for heirloom tomatoes.
Overview
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What is a Heirloom Tomato?
Heirlooms boast a rich history and diverse, distinctive characteristics.
Experts have defined heirloom tomato varieties by production, age, and tradition.
- They are not hybrids and are open-pollinated, meaning you can plant a seed from the mother plant, resulting in a clone.
- Experts have differing opinions on how old a seed must be before receiving heirloom classification, ranging from 25 years to pre-WWII.
- Heirloom seeds were passed down family lines for over a hundred years. Individuals have reported family members taking heirloom tomato seeds with them as they fled their countries years ago, passing down seeds each generation.
Heirloom tomatoes offer unique marbling, both externally and internally. Shapes, colors, and sizes differ across varieties and are typically inconsistent throughout the growing season or year to year. They may look a little different each time they’re grown and have a shorter shelf-life, which is why they’re not usually found in grocery stores. They are typically sweeter and contain fewer seeds than hybrids.
What’s So Special About Heirloom Tomatoes?
Beyond standard grocery fare, these varieties offer unique stories and flavors.
While some of us have only ever experienced classic, red, round tomatoes from the grocery store, past generations experienced bold flavors, exciting colors and textures, and unique family stories from their garden crops.
We adore heirloom tomatoes for their unique flavors, funky shapes, and, most importantly, the extraordinary familial stories you can’t find at the grocery store—the ‘Amish Paste’ plum tomato dates back to the 1870s, originating from Wisconsinite Amish farmers. And ‘Mexico Midget,’ whose seeds we believe to be collected from wild tomato plants in Mexico by a truck driver headed to California. Each heirloom tomato seed has an equally fun and exciting story attached to it.
How to Grow
Let’s discuss the basics and a few differences to help you produce the best heirlooms this season.
Sunlight
For optimal growth, provide a spot in full sun with afternoon shade.
Heirloom tomatoes will perform best in full sun and benefit from dappled afternoon shade, especially in extreme summer temperatures and harsh, direct sunlight. Six to eight hours of full sun is a good standard to go with.
Water
Maintain soil moisture to avoid cracking.
Water consistently so the soil is moist but not soggy. Heirlooms feature thin skin, which makes eating them enjoyable but also makes them more prone to cracking. Irrigate them frequently but for shorter durations than non-heirlooms. Heirlooms can quickly become waterlogged, which causes cracks in their thin skins.
Provide one to two inches of water weekly. If you have received rainfall, use a moisture meter to determine if your plants need irrigation. Avoid overhead watering and opt for deep root watering to help keep foliage dry and plants hydrated.
Soil
Optimize tomato growth with nutrient-rich, well-draining soil and compost.
Provide loamy, fertile, well-draining, nutrient-dense soil with a pH between 6.0 and 6.8. Before transplanting, add a layer of compost to your garden bed to help retain moisture, reduce weed pressure, and add organic matter.
Climate and Temperature
Transplant when temperatures are stable, watching for fungal risks.
Before transplanting outside, daytime temperatures should be between 70 and 80°F (21-27°C). Monitor overnight lows and cover your plants if they anticipate dipping below 50°F (10°C). While they may look fine in the morning, it’s best to avoid stressing plants out, as it could have long-term effects.
Humid conditions increase the risk of fungal disease spreading, so look for symptoms and take swift action.
Fertilizing
Test soil, adjust nutrients, and fertilize wisely for optimal tomato growth.
Perform a soil test before planting to get a baseline and amend as needed. Add a general (5-5-5 or 10-10-10), well-balanced fertilizer or a tomato-specific fertilizer at the time of transplant unless your plot is already high in nitrogen. Too much nitrogen will cause your plant to look very healthy and full of lush, green foliage, but it will decrease the fruit yields.
If using liquid fertilizer, apply when the first flower appears and weekly or bi-weekly afterward. Some growers prefer granular fertilizer, which you can side-dress with. Switching to a high-potassium option when your plants set fruit will encourage more blooms, resulting in more fruit!
Harvesting
Harvest heirloom tomatoes early to prevent cracking and sunscald issues.
As heirloom varieties are more prone to cracking and sunscald than hybrid tomato varieties, harvest them a few days earlier than you would a hybrid. Also, consider your watering schedule and work your harvest days around it. If you water near or at their water content capacity, they’re very likely to crack, so walk your plot the evening before or the morning of watering to avoid this.
Pruning
Prune regularly for optimal growth and disease prevention.
Pruning is essential in growing any type of tomato, but heirlooms can become especially wild if left to their own devices, making this task critical to their success. Remove suckers and unnecessary leaves and empty trusses regularly to open up space for airflow, reducing the risk of foliar disease. Always use clean, dry snips to minimize the risk of spreading disease.
Propagation
Propagating heirloom tomatoes is easy. You can start them from seed or take stem cuttings from established plants.
From Seed
Start tomato seeds indoors using quality, well-draining soil.
Like other varieties, growers should start heirloom tomatoes from seed indoors. The soil should be high-quality and well-draining. Seed companies advise starting seeds indoors six to eight weeks before the last anticipated frost date to avoid leggy or rootbound plants. To find this date, work backward using a calendar.
Find your last frost date, then count the weeks until the recommended sowing date. This is often four to six weeks before the last frost. Sowing times will differ depending on growing zones, setups, and whether heated space is available.
From Stem Cuttings
Propagate tomato plants from suckers for more prolific yields and plants.
You will have stem cuttings after performing weekly pruning and suckering of your plants. Suckers are one of a tomato plant’s attempts to reproduce. The more stems, the more flowers and fruits, leading to more seeds to spread!
Fill a pot with fresh potting mix and deeply bury a sucker in the pot as you would transplant a tomato plant. The plants’ adventitious stem will begin to produce a new root system. Optionally, use root-stimulating hormone to help the sucker grow roots. Put your pot in a semi-shaded spot for several days as it settles in. When roots have developed, your sucker should resemble a new tomato plant that can be transplanted or given as a gift to a gardening friend.
Planting
Plant your tomatoes out after the risk of frost has passed or into a protected space with optional covering if needed. Spacing will depend on the variety, growing zone, and setup.
Hardening Off
Gradually harden off tomato plants for resilient, successful transplanting.
I often hear gardeners skipping this step, but I strongly recommend taking it seriously for your plants’ best interest and long-term success. Slowly allowing plants to acclimate to direct sun, rain, wind, and cooler overnight temperatures will affect how resilient they are when transplanted into the ground. Stress-free, healthy plants are less likely to experience transplant shock and will live healthier and more productive lives.
Start the process five to seven days before you want to transplant them. Do not leave them outside until temperatures are consistently above 50°F (10°C), but 60°F (16°C) is preferred.
Spacing
Space plants adequately for optimal air circulation and disease prevention.
Avoid pushing the boundaries with heirloom tomato spacing to minimize the risk of bacterial and fungal disease. While you could plant them a foot apart, disease and pests will quickly spread, and they may not have ample breathing room.
Since heirlooms lack the added layer of disease resistance that some hybrids offer, allowing plants to dry out and receive ample air circulation is crucial. Space them at 18 to 24 inches for best performance.
Transplanting
Ensure thorough watering and proper planting depth for successful transplanting.
Water your plants well before transplanting. Using a trowel, create a hole slightly larger and deeper than your tomato plant by a couple of inches. Remove any lower leaves and bury the plant deeply. Surround it with soil and gently tamp it down for good root-to-soil contact. Water them immediately and optionally cover them with shade cloth to help with transplant shock in hot climates.
Popular Varieties
With so many options, it’s hard to pick favorites, but here are a few varieties you might consider adding to your garden this season.
‘Cherokee Purple’
Grow ‘Cherokee Purple’ for its rich flavor and history.
This tomato is always flying off our tables at the farmers’ market, and home gardeners love to bring home plants in the spring so they can grow their own. Fruits are 10 to 12 ounces with a rich burgundy shade and green shoulders. The interior flesh is juicy and brick-red in color.
The flavor profile is unbeatable, complex, sweet, acidic, and somewhat smoky. You can almost taste the history! Interestingly, ‘Cherokee Purple’ will grow a deep, vigorous root system without much water. Once established, plants are drought-resistant but should receive consistent and regular water when plants begin to flower and set fruit.
Pro tip: Harvest fruits about three days shy of full maturity to avoid cracking. Set them shoulder-side down and let them fully ripen on the counter out of direct sunlight.
‘Beefsteak’
Choose ‘Beefsteak’ for juicy, two-pound tomatoes, perfect for summer dishes.
You can’t go wrong with ‘Beefsteak’ if you’re looking for a large, juicy tomato for your summer burgers and sandwiches. It’s a classic bright red, and fruits can weigh up to two pounds.
This variety will require caging or trellising to support the weight of the fruits. Its name comes from a seed catalog’s comparison to an actual beefsteak dating back to 1869. You can’t get history like this with hybrids!
‘Pineapple’
Enjoy ‘Pineapple’ tomatoes with their tropical flavor and stunning appearance.
‘Pineapple’ is likely just what you’re imagining from the name. Beautiful on the outside, sweet, acidic, and juicy on the inside. The flavor is slightly tropical, and the gorgeous orange, red, and yellow marbling will have you reaching for your camera.
Common Problems
Heirloom tomatoes are easy to care for once you know what to look for and what your plants need. Here are a few things that could go wrong.
Cracking
Prevent cracking in tomatoes by managing water carefully.
Cracking can occur when plants receive too much water and extreme temperatures, and it is more common in heirloom tomatoes due to their thin skins. Refer to the “Water Requirements” section above for tips on how to water while avoiding cracks and splits.
Low Productivity
Graft for improved disease resistance and higher fruit yields.
Studies show that grafting effectively allows growers to plant tomatoes in the same plot year after year, particularly in protected growing spaces like high tunnels. Grafted plants become more resistant to soil-borne disease, more tolerant of fluctuating temperatures, and produce more fruit. Other ways to increase your plant’s productivity include ensuring proper soil nutrients, minimizing stress, and preventing disease.
Blossom-End Rot
Prevent blossom-end rot in tomatoes with proper calcium and pH.
Blossom-end rot causes rotten black spots on tomatoes’ blossom ends. It may look like a disease, but a lack of accessible calcium causes it. Simple cultural gardening hacks can remediate future issues.
First, ensure your soil has no calcium deficiency, which can lead to weak cell walls and poor development. Second, check your pH levels. A pH under 6.0 ties up calcium, making it unavailable to plants. And lastly, water stress and cold soil can inhibit calcium absorption. The cause of blossom end rot is most often related to inconsistent watering.
Sunscald
Protect tomatoes from sunburn with afternoon shade or shade cloth.
Like humans, tomatoes can become sunburned if not adequately protected from UV rays. Place tomato plants in areas where they experience some afternoon shade or use shade cloth to block some of the sun’s direct rays during prolonged periods of heat and sun to avoid sunscald.
Leaf Roll
Water when leaves curl in hot weather to prevent dehydration.
If you see leaves curling, especially on hot days, your plant may be indicating thirst. It’s not necessarily damaging; water as needed, and keep your eye on the plant. There are also viral diseases that cause leaf roll. We’ll discuss those below, but start with a regular watering schedule to curb leaf roll.
Pests
Control tomato hornworms with natural predators and proactive management practices.
Pests love tomatoes, just like we do! Here are some heavy hitters who might come for your delicious fruits.
- Tomato and tobacco hornworms: One of the most destructive tomato pests, these caterpillars can grow to the length and girth of a grown man’s thumb, eating their way through your tomato (and pepper) patch overnight. Scout early and remove any small hornworms you see (their grown form, the Sphynx Moth, is a pretty cool pollinator!).
Attract parasitic wasps, ladybugs, and lacewings by planting yarrow, fennel, dill, and cilantro. These predators feed on hornworm eggs. Plant sweet alyssum or buckwheat nearby to attract trichogramma wasps who will parasitically lay eggs inside hornworms. Leave them be if you see this; the larvae will feed on the hornworm when they hatch. You can also hand-pick hornworms and move them to wild nightshades if you want to support the adult form of this insect: the sphinx moth.
Pro tip: Invest in a cheap black light and hunt for hornworms at night. They’ll glow in the light and be easily spotted!
- Flea beetles: These metallic jumping beetles are small but mighty, causing mass destruction in a short amount of time. Cover young transplants with insect netting to prevent them from being destroyed. More mature plants can take more damage, but you should avoid it. Delayed planting can also deter flea beetles from choosing your garden as their home.
- Aphids: These sap-sucking pests are more of a nuisance than a genuine threat to established tomato plants. However, you want to catch their first generation as they can produce multiple generations in one season. Not only do they affect tomato plant growth, but the sticky honeydew residue they leave in their wake attracts ants, which can further inhibit growth.
To remove aphids, blast them with water, prune the affected branches, or hand-pick them. Plant chives, echinacea, coreopsis, and yarrow to lure natural predators like hoverflies and ladybugs to your garden.
Other pests include cutworms, leafminers, tomato fruitworms, and tomato mites. As with any pest, it’s essential to identify them early and take action quickly. Start with mechanical means and then move to organic insecticides if necessary.
Diseases
Prevent septoria leaf spot with good pruning and fungicidal treatment.
Heirloom tomatoes can’t ward off diseases like hybrids, so watch out for signs of the many that can plague them. Correct identification is crucial to treat properly!
- Early blight: Look for brown spots on the leaves and stem just above the soil surface line in the early season when conditions are moist and temperatures are above 75°F (24°C). This disease can be pretty destructive to young transplants. Symptoms in more established plants may appear as brown and yellow bullseyes on leaves and leaf shrivel. You can remove damaged leaves as they appear to control the spread.
- Fusarium wilt: This fungus affects the vascular system of tomato plants, causing a lack of water flow, causing wilt and death. It can spread rapidly, destroying large plots in a short period. It starts with wilting leaves and then moves to the entire plant. There is no cure for fusarium wilt.
Several soil-borne pathogens can cause this disease, which is hard to treat once it’s present. Fungicides and mycorrhizal fungi may kill it. To reduce the risk, avoid soggy water and follow proper crop rotation.
- Septoria leaf spot: This fungal disease appears after heavy rainfalls when conditions are wet, hot, and humid. Symptoms include small, brown, circular leaf spots that will eventually yellow the whole leaf and cause them to drop. Don’t confuse these perfectly round spots for the irregularly-shaped spots of early blight.
This disease attacks older, weaker leaves first, so to reduce this risk, prune lower leaves, provide good air circulation, and space plants appropriately. Use sulfur or copper fungicides to treat this disease early and prevent its spread to healthy foliage. Dispose of infected plants completely, and do not compost.
- Bacterial wilt: When conditions bring hot and humid air, bacteria in the soil quickly move through the tomato stems, killing your plants almost instantly. Growers often assume the hot weather causes this wilt and misdiagnose the issue. Remove infected plants and throw them away.
Others include spotted wilt virus, tobacco mosaic virus, Alternaria leaf spot, Cercospora leaf spot, southern blight, and anthracnose fruit rot. Keep your garden tidy and remove debris immediately to avoid spreading disease that may be harboring on weeds or pruned cuttings. Some disease-causing bacteria can overwinter in debris, dirty tools, and weeds. Always practice proper crop rotation, clean tools, and monitor your plants closely.
Always refer to the product label and recommended dosage when using sprays to treat disease.
Final Thoughts
The history of heirloom tomato varieties offers us a brief glimpse into the past. Imagine your ancestors sitting at a table enjoying the same deliciously juicy tomato you enjoy today. What a treat!
While hybrids have their place in the gardening world, I recommend adding an heirloom or two to your summer lineup. You can almost taste the history.
