There are many good reasons that tomatoes are the #1 crop grown by homeowners. Store prices are high, commercial produce is usually bland, the plants are relatively easy to grow, it only takes 2-3 months to get a crop, and one plant can produce for many months (in some cases for several years).
Of course, as with any crop, the more you grow it, the more you learn. Many experience beginner's luck, then get frustrated in the future. Here are a number of pointers.
The diagram above shows how the majority of tomato plants grow. As the stem tip elongates (only the last few inches of a stem can stretch and grow) it produces new sets of leaves and flowers. The flowers bloom and fruit develops. The fruit matures and is ready to harvest by the time the stem has grown an additional 2 to 3 feet longer. This is known as the indeterminate pattern of growth.
EXPOSURE Although full sun is best, most varieties will produce a good crop with 1/2 day and I've grown many good crops in exposures that would at best be called light shade. Generally, if it's outside, it can work.
SOIL Tomatoes plants can grow in any soil as long as it doesn't remain constantly soggy. It is more important just to remember to rotate crops properly. Generally, it is safe to grow tomatoes in the same soil once every 3 years. This off time is required to rid the soil of remnants (rotting tomato roots) of the last tomato crop. Fatal diseases, commonly Fusarium or Verticillium, are the diseases associated with dead and dying tomato, potato, pepper or eggplant roots. This really doesn't have anything to do with poor care. Any organism that is dying is consumed by bacteria or fungi whose presence is detrimental to the health of nearby related living organisms. You can't remove these dead roots (most are hair-like) unless you are willing to work with a microscope and tweezers. Unrelated crops (corn, beans, squash, lettuce, cabbage, broccoli, radish, strawberry) are not affected. Many hybrid tomato varieties can tolerate being planted in the same soil for a few years, however, crops will gradually decline (turn yellow and die prematurely). Heirloom varieties will generally not perform well the second year. This means that you will need to divide your garden into at least 3 sections and keep track of what you planting. All crops require rotation for best results. If you only grow tomatoes give your ground some time off by growing a crop in containers.
IN CONTAINERS Tomatoes will grow in any potting soil. Our Laguna Hills Nursery potting soils are better than most and will last longer (years instead of months). The larger the container you choose, the larger the crop. Although we tell you that a 5-gallon container is the smallest suggested size, I've eaten many fruit from plants that were still in their original 4" pots. A local expert recommended 15-gallon as his favorite size.
PLANTING DEPTH Tomato plants readily form roots on their stems if in contact with the soil. I would recommend planting your young plants about 1" deeper so that they can root directly from their stem into your soil. This would negate any problems that could occur if the wholesale grower had used a poor quality (cheap) soil. Cheap soils generally contain a lot of composted wood or bark and can promote root rot diseases as they turn to muck. If you plant too deeply, any root deeper than a foot in the ground may die from suffocation, but would be replaced by new roots developing closer to the surface.
On some greenhouse farms the ability of the stems to root quickly is used to the farmer's advantage. One method is to grow the roots hydroponically in a gutter (or trough) filled with a nutrient rich solution. As the stem elongates the fruit matures and is harvested. When the stem gets about 2 feet too long the foliage at the base is removed and the lowest two feet of the stem is stuffed into the trough. This stem quickly develops roots. After the stem grows another 2 feet the bottom 2 feet of the root is cut off and the process repeated. The farmer can keep the same plant producing continuously at roughly the same height for several years.
WATERING Tomato plants prefer consistently moist soil, but are highly forgiving of short periods of drought. They visibly wilt severely when dry but recover completely when irrigated. It is important that tomato leaves do not stay wet for long periods. Disease spores germinate in stationary water droplets and infect the leaves. If the weather is warm or windy and dry, you can irrigate any time of the day. Under cool humid conditions try to water between mid-morning and early afternoon. If you can avoid getting the leaves wet, water anytime. In our potting soil, or in a clean mineral soil, it is nearly impossible to
overwater. In soils containing a lot of compost (most commercial potting soils) allow the soil to look dry on the surface before the next irrigation. In a backyard setting you have to compensate for the water used by nearby plants. Any large tree or bush within 50 feet can be stealing water intended for your crop. Farmers will usually trench along the edge of their fields at least every 5 years to sever invading roots from nearby woody plants, especially large windbreak trees.
So how much water does your plant need? You just have to guess. Experienced gardeners just get a feeling. On a field with a uniform crop, no walls, no competing plants, a farmer can install tensiometers to determine when to water, or consult a nearby extension office with an evaporation tray to make a better guess. Generally, if your soil doesn't stay muddy and your plants don't wilt between irrigations, you are fine.
FERTILIZING Tomato plants are relatively light feeders. In the short term, anything works. Over a long period it is best for the plant, and your soil, to apply fertilizers from an organic source. We notice that the foliage of a container grown plant will turn purple from lack of minerals.
SUPPORT Tomato plants do not require support, however, they will take up less space and are easier to harvest if staked or caged.
PESTS In early spring you may find a colony of thorny-looking black bugs on a stem. These are baby keeled treehopper bugs that are related to Aphids. The adults are green. They suck juices from the plant, but don't do much damage. Generally in early summer the hornworms (huge caterpillar of a hawk moth) magically appear. You don't usually notice them until they are 3 weeks old (the caterpillar is on the plant for 4 weeks) and eating a whole branch at a time. You can pick them off (they have a strong grip), squish them or cut them in two. If you don't want to directly handle them apply a product containing the organic pesticide
spinosad about once every 3-4 weeks starting in July and continuing well into fall. Use the mylar Bird Scare Tape to keep birds away. Rats, possums and raccoons are more challenging.
DISEASES During late winter into spring, the diseases associated with wet foliage are most challenging. I have used electrical fans to help dry the leaves after a storm. Over the last few years we have had a lot of misty spring weather which is ideal for causing
Late Blight. This is the same disease that caused the Irish Potato Famine. The disease starts as dark spotting and quickly turns surrounding stems black. Pick off infected parts quickly to cure the plant. AGRI-FOS is a fertilizer/fungicide that can help prevent Late Blight. So far this year our storms have been followed by dry, windy weather and we've seen relatively few diseases associated with wet leaves (except on roses). Just be observant. There are quite a few other diseases associated with foliage spotting. Most are not serious (unless it starts raining consistently) and are best cured by pinching off. When bottom leaves turns yellow (sometimes on one side of the stem) that is a sign of root problems. This can be caused by soil that doesn't have enough oxygen (too much compost and/or poor drainage) or by lack of proper soil rotation. AGRI-FOS can cure one type of root rot disease, but there are several.
OTHER PROBLEMS Large fruited varieties (like beefsteak) often suffer from
Blossom-end Rot. This is not a disease, but rather a failure of the plant to properly finish the fruit due to a lack of calcium. The bottom (blossom-end) of the fruit turns hard and dark. It's usually not a lack of calcium in the soil, but rather a underdeveloped root system. Often the roots continue to develop and the problem disappears. You can treat the plants by spraying the developing fruit with a product containing calcium. I bet milk will work. Tomato varieties with small to medium size fruit are rarely afflicted.
The question is how to determine what varieties you should grow. There are hundreds. One of our suppliers grew 250 varieties! Next week I'll tell you what I know about many of the most popular varieties. Part of the fun is growing an unknown. You may be pleasantly surprised.
