Tomato Growing Tips

You’re not alone on your “Grow Your Own” journey

Grow your own food advantages: We all know that the taste of any store-bought tomato (even organic ones) cannot compare to homegrown tomatoes. It is also great to be able to experiment with so many different varieties – each with its own unique flavor.

The Deep Roots innovative growing method is designed to make food gardening successful for beginners and all gardeners year after year. We accomplish this by following a new soil science that first supports the beneficial soil microbes. We don’t fill our raised beds with conventional soil and instead use 100% Microbe-Rich Compost. We use top quality “worm castings” (worm poop) instead of commercial organic fertilizers. The microbes in our compost and in our worm castings feed the plants.

Below are links to our growing method.:

Plant tomato seeds or seedlings?

Buy or grow seedlings (transplants). Most new gardeners prefer to buy young starter plants called “seedlings” or ”transplants.” Advanced gardeners grow their own seedlings from seeds.

Beginner gardeners in Chicago area (climate zone 5b) should plant seedlings at the end of May to avoid cold nights. Some neighborhoods in Chicago are warmed by the “lake effect” (climate zone 6a) and can plant in mid-May.

Tips for buying seedlings (transplants): Always buy seedlings immediately after they are delivered to the store. If you have tiny seedlings in very small pots and are not ready to plant yet, move them to larger sterilized pots. Don’t bu seedlings with yellowing leaves.

Tomatoes are sensitive to temperature

Understanding the temperature tolerances of the vegetables you grow is crucial for their growth and productivity. By providing the optimal temperature conditions, you can ensure healthy plants and a bountiful harvest. Peppers and eggplants have similar sensitivities. Most tomato seedlings survive cold nights (temperatures between 40º and 50º). Severe damage occurs under 40º. Learn about season extension techniques to protect tomatoes from extreme cold and heat.

Cherry tomatoes are warm-season plants and prefer temperatures between 70°F to 80°F (21°C to 27°C). They can tolerate slightly cooler temperatures but don't grow well in temperatures below 50°F (10°C). If temperatures exceed 95°F (35°C), cherry tomato plants may drop their flowers and fruits.

Roma tomatoes are also warm-season plants and prefer temperatures between 70°F to 85°F (21°C to 29°C). They can tolerate slightly cooler temperatures but don't grow well in temperatures below 55°F (13°C). Like cherry tomatoes, Roma tomatoes may drop their flowers and fruits if temperatures exceed 95°F (35°C).

Heirloom tomatoes are also warm-season plants and prefer temperatures between 70°F to 85°F (21°C to 29°C). They can tolerate slightly cooler temperatures but don't grow well in temperatures below 55°F (13°C). If temperatures exceed 95°F (35°C), heirloom tomato plants may drop their flowers and fruits.

Spring temperatures are very unpredictable during climate change. Most Zone 5b and 6a experienced gardeners prefer to plant tomato seedlings within the official planting date (May 10-15). Experienced gardeners have some tricks to protect against unexpected later frosts. Be patient when planting tomatoes and other very cold-sensitive crops that should never be exposed to under 50º F. To be safe beginners should plant on May 18 a little later than the official last frost date.

How to plant tomato seedlings

Preparing the soil: If your bed is filled with our 100% compost and you have added 2” fresh compost after the previous growing season, just add 1 cup of worm casting to your hole. But, if your bed is filled with conventional soil, dig a bigger hole to make room for several cups of half-and-half compost and worm castings mixture. Another option if you are planting in conventional soil is to dig out the top 4 to 6 inches of the soil and replace it with our Microbe-Rich Compost.

Planting the seedling: Use biodiversity planting – only one or two tomatoes per bed – 2 feet apart to get air flow that prevents dampness that promotes fungi and blight. Fill the spaces on the edges and between the tomatoes with other plants.

Give your tomato seedling an amazing head start. Prune bottom leaves and plant deep. If it’s a large seedling prune the bottom leaves off and dig an extra deep hole. Plant the roots extra deep so a lot of stem is covered by soil. The hair on the buried stem will become roots and produce a healthier tomato plant. View this excellent tomato planting video – but remember we use top quality worm castings instead of traditional fertilizers.

Add mulch and water deeply, but don’t over water

Watering tips from Oak Park’s Tomato Lady (Lissa Dysart): “Don’t water very much, other than at the beginning to help them get settled in. I’m a tough-love gardener, so I don’t pamper them. Watering a little bit every day is a mistake, because you’re frequently only watering on the surface and because the water evaporates really quickly. If you need to water due to heat or new plants, try to water every other day or every several days, but water really deeply when you do. If there’s been no rain, I’ll water to keep a medium level of hydration on the plant, especially when they’ve set fruit, to avoid cracking. When it hasn’t rained for a while and the plant has fully formed fruit, the sudden influx of water from a rainstorm can cause the fruit to rapidly increase volume, and then crack, so I will give them a drink in a period of no water to avoid that issue. Generally speaking, the less you water your tomatoes, the denser the flavor, so I err on the side of less watering.” – Tomato Lady

We highly recommend ordering seedlings from Lissa’s incredible list of vegetable varieties that she grows in her house and yard. Her plant list and pre-order form is released to the Tomato Lady fan email list in early-spring. Subscribe HERE. Email her at tomatoLadyOakPark[at]gmail.com

Sunlight and temperatures

Tomatoes always want morning sun. The sooner the sun strikes their leaves in the morning, the faster the dew will evaporate and the healthier the plants will be. Choose the sunniest spot in your garden. Too much sun can be a problem to your tomatoes caused by intense, direct sunlight for extended periods during very hot weather. Usually this is not an issue in Chicago area.

Extreme heat is bad for tomatoes: Excessively hot temperatures - over 90 degrees consistently during the day and 75 degrees or higher overnight - stress tomato plants. Most tomatoes stop producing blossoms and fruit, and simply concentrate on surviving. The 2 Chicago heat waves in July 2022 shut down 12 hybrid tomato plants in the Deep Roots experimental garden in Oak Oak IL for the rest of the growing season. Protect tomato plants during high heat with shade cloth. View this excellent video about heat protection of crops.

Determinate OR indeterminate

Determinate and indeterminate tomatoes. Your plants are either determinate (meaning they will grow to a certain height, often about 3-5 feet tall, and then produce their fruit all at once), or they are indeterminate (they just keep on growing and producing fruit as they grow). They stop growing when cold weather hits.

Growing cherry tomatoes is easier. Most cherry tomatoes are indeterminate and have a large, sprawling growth habit that requires pruning and support. When space is limited, many gardeners choose determinate varieties as they grow in a more compact, bush-like shape. They ripen in small batches throughout the season. You usually don’t have to protect them from squirrels in the Chicago area. They don’t require as much careful pruning. Kids and adults love to eat them right off the plant.

Pruning tomatoes

Pruning helps maintain balance between vegetative (leaves and stems) and reproductive (flowers and fruits) growth, improves airflow to prevent disease, and can even help your plants produce larger fruit. As the plant grows, remove the shoots or "suckers" (see diagram below) which develop between the main stem and the leaves, up to the first flower/fruit. Above the first fruit cluster, let the shoots develop two leaves and then pinch off the tips.

Indeterminate and determinate tomatoes are pruned differently. The self-pruning gene causes determinate tomato plants to stop the growth of their shoots once blossoms form at their ends. On the other hand, indeterminate tomatoes, which lack the self-pruning gene, will simply flower blossoms along its shoots, and continue to grow throughout the appropriate season. Determinate tomatoes need no pruning other than removing all suckers below the first flower cluster because pruning won't affect their fruit size or plant vigor. If you do any pruning at all above the first flower cluster on determinate tomatoes, you'll only be throwing away potential fruit.

How to prune video we like is prune your tomato plants. See more pruning tips in the vertical growing section below.

Growing tomatoes vertically

Is growing vertically always the best option? Vertical growing is always needed when space is limited. The University of IL Agricultural Extension says: “Tomatoes can be grown successfully either on the ground or staked, but plants grown on the ground require less work, produce more per plant, and are less susceptible to blossom-end rot. The advantages of staking are cleaner fruits, no loss from soil rot or anthracnose and, sometimes, easier picking. If you grow tomatoes on the ground, mulching with clean fresh straw will reduce anthracnose and fruit rots, and help to keep the fruits clean. Also, the mulch will conserve moisture and control weeds.”

Trellis or staking: Most people grow indeterminate tomatoes which will need a trellis, staking, a tomato cage, or another way to keep the plant from collapsing. Most large determinate tomatoes need a cage or staking to. There are many ways to trellis tomatoes. A wooden or metal frame with wire or netting grid attached secured to the raised bed is best. Traditional trellis designs assume you are growing all the tomatoes in one spot close together. BUT, we strongly recommend you put at least 2 feet or more between tomato plants or grow them in separate large containers.

Tomato cage: Since it’s very important to space the tomatoes 2 feet apart we suggest a tomato cage for each plant. Large tomato plants can topple over if their only support is a tomato cage. Before you plant your seedlings, secure your tomato cage with a sturdy 50-60 inch tall stake down the middle of the cage. Secure the main stem to the stake as it grows. Contact Deep Roots support if you want to borrow some of our extra large tomato cages stored at our Deep Roots garden in Oak Park, IL.

There are several methods of staking and pruning tomatoes.

Tips from University of IL Agricultural Extension website:

  • Start early with the staking. Shortly after transplanting, drive a stake about 6 feet long and 1½ inches in diameter into the soil 8 to 10 inches deep and 3 inches away from each plant.

  • Tie a string tightly around the stake and loosely around the plant. Tie a knot just below a branch so that the plant cannot slide down.

  • When the plants are 12 to 15 inches high, remove all but one or two main stems and tie them loosely to the stake, using soft twine or cloth.

  • As the plant grows, remove the shoots or "suckers" (see diagram above) which develop between the main stem and the leaves, up to the first fruit cluster.

  • Above the first fruit cluster, let the shoots develop two leaves and then pinch off the tips.

  • Tie the plant loosely to the stake every 10 to 12 inches.

Squirrel protection

There are several ways to deal with squirrels biting your tomatoes. They are interested in the juice mainly,

  • Place heavy-duty deer netting, chicken wire or other wire fencing around the tomato plants to keep the squirrels from spreading diseases and ruining tomatoes.

  • Plant only cherry tomatoes since squirrels rarely bother them.

  • Protect individual ripening fruits with a small brown paper lunch bag tied to the plant when the tomato turns from green to beige.

  • Bring tomatoes indoors when they just start to ripen. Speed up the ripening process in a paper bag that includes several green tomatoes and an apple. Ethylene gas released by apples, bananas and tomatoes naturally ripen fruit. This is the preferred method used by many Deep Roots experienced gardeners.

How to harvest tomatoes

“Harvest the fruits when they are pink except during periods when the daily mean temperature is above 70° F. At such high temperatures pick the fruits just as they are turning color and keep them at 68° F. for further coloring. These fruits will be firmer and have better flavor than those ripened on the vine when temperatures are high. Fruits exposed to direct sunlight will reach a temperature 20 degrees higher than that of shaded fruits.

In the fall just before the first frost, pick the large green fruits as well as the riper fruits. Ripen these fruits at about 60° to 70° F. in the dark. By sorting them out every 2 or 3 days you will have a gradual supply for about a month.” – University of IL Agricultural Extension

Environmental Pest Management (EPM)

An integrated approach is key

Diseases in tomatoes can be greatly reduced by good cultural practices and carrying out a fungicide dust or spray program. EPM for organic food gardening is responsible environmental stewardship. EPM is modeled after the older Integrated Pest Management (IPM) that allowed use of toxic chemicals for extreme pest invasions.

Use the organic safe sprays we recommend in our EPM post (link below). We practice these EPM principles for all of your vegetables. Details are in our EPM post. Contact your local botanic garden information service OR state university agricultural extension for help identifying and treating pest problems.

Our Innovative Food Gardening Method

Learn more in our two recently revised blog posts.

Our online store

See our online store for details about prices, ordering and delivery of raised beds, compost, worm castings and more. Please contact our customer support team before placing an order online so we can assist you with the details and answer your gardening questions.

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