Growing Tomatoes (or any Vegetable) from Seed
Start tomato seeds indoors 4 to 6 weeks before average last spring frost, which is April 15th here in St. Louis. Transplant them out when the soil temperature is ideally 70 - 90 degrees, generally in mid May. The time to start those tomato seeds here in St. Louis is late March.
(The proper time for sowing seeds depends upon when plants may normally be moved outdoors. The periods range from 4 to 14 weeks, depending upon the speed the seedlings grow and the conditions in your home. Check the back of the seed packets to determine when to start your seeds for planting times. Some seeds should be started inside, while others such as lettuce and spinach should be planted directly into the garden.)
|Hardening Off Schedule|
If you are planning on buying tomato plants, the advice given by horticulturists and gardeners alike in the St. Louis area is to buy the varieties you like, when they are made available at the nurseries, and keep them indoors until the middle of May.
Tomatoes are grouped into two main types according to growth habit and production.
Determinate types grow in a compact, bush form, requiring little or no staking. Fruit is produced on the ends of the branches; most of the crop ripens at the same time. One or more successive plantings will ensure an extended harvest period. Determinate types are often the choice of those who want a large supply of ripe fruit at once for canning. Staking is generally not needed.
Indeterminate varieties continue to grow and produce fruit all season until first frost. Tomatoes in all stages of development may be on the plants at one time. The plants set fruit clusters along a vining stem, which grows vigorously and long. Under optimum conditions, some can grow over 15', but in most home gardens they generally reach about 6'. Some indeterminates have a bush form with stockier vines, which set fruit clusters closer together. Staking is definitely needed for indeterminate varieties.
In between these two types are the Semi-Determinate. The plants will grow larger than determinate varieties, but not as large as indeterminate. They produce a main crop that ripens at once, but also continue to produce up until frost. Staking is recommended.
You will see various letters or string of letters (A, F, N, V, T and or St) on seed catalogs or packages that denote the disease resistance of the plant. The following are the most common diseases that affect tomato plants and how to avoid or treat them.
Early Blight or Alternaria Stem Canker (A)
The fungus Alternaria solani, which is present wherever tomatoes or potatoes are grown, causing early blight. Prevalent throughout the United States, the fungus overwinters on tomato plant debris. Spores can then spread to tomatoes in spring via wind or splashing rain, but they need wet leaf surfaces to germinate and grow. Low leaves that drip with dew each morning provide perfect conditions for early blight.
When tomato plants begin to set their fruit, brown spots will develop on the lowest leaves of the infected plants. As the spots expand and become more numerous, the leaf tissues between the spots may turn yellow before the leaf eventually withers. The spots will have outer rings around a bull’s-eye center.In most cases, early blight damage will be limited to the bottom third of a tomato plant, where they tend to be more damp. The plants still may manage to yield a good crop, if treated or pruned.
Watering tomatoes in the morning allows the leaves to dry out during the day. If this is not possible, water the plants at the base and try to not get the foliage wet. Planting tomatoes in different locations (plant rotation) is a good idea, assuring the new plants are not planted with the disease carrying spores.
When you see the first early blight leaf spots, use pruning shears to clip off all leaves within 12 to 18 inches of the ground, removing no more than 20 percent of the plant’s total leaf mass. An organic fungicide applied at first site, may help to keep the fungus under control.
(Other diseases or wilts will also produce spots and yellowing, but the spots will not have the rings around them as on Early Blight.)
Fusarium Wilt (F, F1, F2 or F3)
Fusarium wilt is a soil fungus that is present when the daytime temperatures are 80 degrees and above for many consecutive days. Once the fungi enters the plant through the roots, it will multiply in the plant’s vascular system, the leaves on individual stems to show symptoms first. The infected plants tend to grow normally until they begin to set fruit. At that point, leaves on some stems will start to yellow and wilt severely in midday sun. As the disease progresses, more stems and leaves will yellow and wilt, until the plants eventually collapse and die. Plant tomatoes in different locations for up to four years will help prevent this disease
Plant parasitic nematodes, are small microscopic roundworms which live in the soil and attack the roots of plants. Yield reductions can be extensive but vary significantly between plant and nematode species. In addition to the direct crop damage caused by nematodes, many of these species have also been shown to predispose plants to infection by fungal or bacterial pathogens or to transmit virus diseases, which contributes to additional yield reductions. Rotating crops and growing resistant varieties can help prevent problems. Keep beds weeded, as many weeds serve as nematode hosts. Planting French marigolds with tomatoes can help reduce the nematode numbers.
Verticillium Wilt (V)
Verticillium wilt symptoms on tomatoes are similar to those of Fusarium wilt. Often no symptoms are seen until the plant is bearing heavily or a dry period occurs. The bottom leaves become pale, then tips and edges die and leaves finally die and drop off. V-shaped lesions at leaf tips are typical of Verticillium wilt of tomato. Infected plants usually survive the season but are somewhat stunted and both yields and fruits may be small depending on severity of attack. To combat verticillium wilt, grow any of the widely available resistant varieties, and rotate plantings so you’re not growing in the same soil more than once every four years. Plants that show only mild symptoms can sometimes be nursed through the season with mulch and regular watering.
Tobacco Mosaic Virus (T)
The foliage shows mosaic (mottled) areas with alternating yellowish and dark green areas. Leaves are sometimes fern-like in appearance and sharply pointed. Infections of young plants reduce fruit set and occasionally cause blemishes and distortions of the fruit. The dark green areas of the mottle often appear thicker and somewhat elevated giving the leaves a blister-like appearance.
St=Stemphylium Grey Leaf Spot
The disease is limited to the leaf blades. The fungus infects plants from the earliest seedling stage to maturity. Initial symptoms include one to several minute brownish black specks that appear on both surfaces of the leaf. The area changes in color from brownish black to grayish brown, as the spots enlarge and these centers crack and partially drop out to give the leaf a shot-hole appearance. The entire leaf then turns yellow, droops, and eventually dies.