Finally the tomatoes are planted! The cool weather this spring led me to wonder if the soil would ever be warm enough to plant them. (Planting tomatoes in soil which is too cold will stunt the growth of the roots and slow the development of the plants.) Tomatoes are one of the most popular foods to grow, probably because the ones we can buy in the grocery stores can’t compare to the taste or aroma of the big red fruit that speaks of summer; nothing beats a homegrown tomato fresh from the vine.
Yes, I did say fruit because scientifically, a tomato is technically a fruit. That is because it is formed from the ovary at the base of the flower and it contains seeds, much like apples, oranges, cherries and other fruits. We refer to the tomato as a vegetable because of the way we cook with it; it is usually used in savory dishes like salsa or tomato sauce rather than sweet dishes. And in 1893, the United States Supreme Court declared that tomatoes fell under the category of ‘vegetable’ and therefore were subject to import tariffs that applied to vegetables but not to fruits.
The tomato (Solanum Lycopersicum) is a member of the nightshade (Solanaceae) family and like eggplants and peppers is a heat seeking plant. All are related to the potato. The tomato originated in the South American Andes and its use as a food began in Mexico and spread throughout the world after the colonization of the Americas. The most common tomatoes are red but they can be green, yellow or purple. Recent interest in heirloom varieties has introduced this wide range of colors to the marketplace. They can be determinate or indeterminate in growth type. Determinate plants stop growing once they flower and the fruit ripens in a determinate period of time. Indeterminate plants continue to grow, flower and ripen fruit throughout the growing season. While it might seem to be ideal to have a continuous crop of tomatoes throughout the season these plants can become quite large and unmanageable, and will need to be staked or grown on a trellis. Tomatoes can be of the beefsteak, Roma, heirloom, cherry or grape categories.
Once your tomatoes are planted, they should receive a least one inch of water per week during the growing season. Water by soaking the soil; avoid overhead sprinkling. Frequent, gentle cultivation around the plants should keep the weeds down. Tomato roots are very close to the surface so be careful not to cultivate too close to the plant. After the plants flower a side dressing with some organic fertilizer such as compost or manure will aid in their growth and fruit development. Three to four inches of organic mulch, such as wood chips, grass clippings or weed free straw should prevent weed seeds from germinating as well.
We generally think of growing tomatoes as easy, but there are some common problems that can interfere with our crop production. Drought, temperatures above 90° during the day, or below 60° or above 70° at night can cause flowers to drop. No flowers – no fruit. And tomatoes can be sunburned when there is not sufficient leaf cover to protect them in hot, dry weather. Cutworms can chew plants off at the stem and tomato hornworms chew on tomato leaves.
Blossom end rot is one of the most common issues in growing tomatoes. Blossom end rot exhibits as tan to black flatten spots at the blossom end of the fruit. The rot is due to the malformation of the skin at the end that allows fungi and bacteria to get inside. Blossom end rot is related to a calcium deficiency at the time the flower buds are forming and blossoming. The calcium deficiencies are usually found in cool damp periods in spring when the soil temperature is below 50° and the soil biology is not yet active. Once the soil warms up the calcium is more available. (Another good reason to wait to plant your tomatoes until the soil has warmed.) If you are concerned about the amount of calcium available in your soil you should test your soil before adding any ‘climatic’ lime. Too much calcium can be as bad as too little. The ideal PH level is 6.2 – 7. If you have already planted your tomatoes and are concerned about blossom end rot you should monitor your soil temperatures both day and night. If you experience several days of cold temperatures, it is best to add calcium in a soluble form, such as calcium nitrate. Mix 1 cup to 5 gallons of water and add one quart of the mixture to the soil around each plant. This will direct the calcium to the plant roots and not raise the PH level above 7.0
There are several other diseases that can affect your tomatoes and we will discuss those in future columns. In the meantime good luck with your tomato crop.