Growing Tomatoes

For many gardeners, nothing can beat the flavor of a sun-warmed homegrown tomato, picked at the peak of ripeness.  With many tomato varieties taking about three months to produce the first fruit, it’s no wonder there are many tips and tricks for those anxious to grow the perfect plant.

With hundreds of plots in our community gardens over the years, we’ve seen many different tomato varieties in the flesh, almost every type of disease run its course, ingenious trellises, under-pruning, overwatering, giant hornworms, and the neglected tomato in a forgotten plot, absolutely thriving! Here are some things that work, and don’t work in Chicagoland gardens:

Heirloom, F1 hybrid, or new open-pollinated variety? This is up to you, but generally – heirlooms have a better reputation for flavor, many F1 hybrids have documented disease resistance, and new open-pollinated varieties (such as tomatoes from the Dwarf Tomato Project) combine some of the best features of both through volunteer cross-pollination efforts. Check out our post, De-Mystifying Seed Catalogs and Seed Packets for definitions.


Heirloom tomato harvest.


Buying Plants and Starting from Seed
If you’re buying plants, inspect them closely and look for signs of stress and disease. Yellowing or purpling leaves due to inadequate fertilizer, leggy stems, or rootbound plants are stressed and more susceptible to pests and diseases from the start. If tomatoes are already showing signs of disease at the nursery, they’re not going to improve in your garden.

When starting plants from seed, be sure not to sow or transplant them too early. Many gardeners make the mistake of starting their seeds too soon, thinking they will get an earlier harvest than their neighbors. While their plant may seem larger for a few weeks, it will generally produce the first tomatoes around the same time as a seed started a little later – which in Chicago is generally around the last week of June through mid-July. Transplanting too early in our climate means the tomato plant will be in cool, wet soil too long – which is ideal for soil-borne disease to take root.


A sturdy, healthy seedling ready to transplant.


You can plant your tomatoes deep, meaning you bury the lower part of the stem in soil. New roots will form directly from the stem, giving the plant a sturdier system for supporting heavy production. Be careful not to ‘rough up’ the roots – this damages them and can provide an easier entry point for soil-borne fungal diseases. Water your seedlings thoroughly to reduce transplanting stress.

Water the soil, not the leaves. You will find that your tomatoes will need more water after July when the plants are bigger and producing juicy tomatoes. Keep watering on a consistent schedule to avoid blossom-end rot.

Add a little all-purpose fertilizer to the transplanting hole, and more again in late June/early July as a side-dressing.

Most tomato varieties benefit from growing on trellises. Indeterminate tomato varieties will keep growing, growing, and growing while providing a steady harvest. If you have an indeterminate tomato – especially on a short trellis, you’ll need to prune the suckers and growing tip mid-summer or it will go wild. If you’d like to avoid this, choose a determinate tomato plant, but keep in mind – production tends to be all-at-once and then the plant starts to die, while an indeterminate tomato will continue producing until the first frost. Semi-determinate and many dwarf varieties are determinate in growth habit (they stop at 2-5′), but continue production over a longer period like indeterminate tomatoes and don’t die back as soon as determinate tomatoes.

Pinching Blossoms
Tomatoes come from the flowers. If your plant is fairly small when it begins to flower, it’s a good idea to pinch the blossoms off for a few weeks, so the plant can grow more stems and leaves to support a a heavy harvest. However, if you continue to pinch off the blossoms, you won’t get any tomatoes at all.

Pinched-off tomato flowers.

Pinched-off tomato flowers.

By the time you notice symptoms of disease, it’s usually too late to do much about it. Prevention is best – either through selecting disease-resistant varieties, planting in sterile soil, or inoculating the roots at transplanting time with beneficial fungi or bacteria. Plant diseases take root when the plant disease triangle is formed – a susceptible host (your tomato plant), a present pathogen (the fungus or bacteria), and a conducive environment (your garden). You can try to make less of a conducive environment for the pathogen by cultivating healthy soil, giving your plants adequate airflow, preventing them from getting nutrient-, water-, or space-stressed, and avoiding damage to roots, stems, and leaves.

We typically see aphids, mites, and tomato hornworms in Chicagoland. Aphids tend to be on over-fertilized plants, mites on dusty leaves, and hornworms are often missed until they are enormous! If you’re noticing odd triangle-shaped pokes in your tomatoes, keep in mind – birds love to get that juice, especially when we’re experiencing a long period without rain.

Harvest your tomatoes green, ripe, or in-between! Store at room temperature – with the stem side down to keep from ripening too fast, or in a paper bag to hasten ripening.