Tomato plants require rich soil, prolonged warm temperatures and nutrients such as calcium to grow well. Areas with warm days and cool nights, deficient soil and heavy spring rains can have difficulties growing them. However, problems with growing tomatoes can be remedied with variety selection, soil modification and cultural practices.
Tomatoes need consistent warm temperatures to grow well. Hot days followed by cool evenings, or a long stretch of cold and rainy weather, can cause a decline in vigor and increase susceptibility to disease. Planting only when the soil and air temperatures are consistently warm is one way of avoiding this problem. However, some areas of the country will have temperature fluctuations all season long. If that is the case, select tomato varieties that have been grown and extensively tested in cold and short season climates. Glacier, Stupice, Juliet and Scotia will all reliably produce fruit even during cool summers.
The most common nutrient-related disorder of tomatoes is called blossom-end rot. A dark, shriveled patch begins on the end of the tomato, and slowly becomes larger, rendering the fruit unusable. This is caused by a calcium deficiency in the soil. Areas of the country with acidic soils will find this problem to be rather common. Applying agricultural lime in the spring will raise the levels of available calcium and provide a cure. A soil test should be done every year prior to liming, as too much lime can be worse than too little.
Nitrogen levels also cause problems for gardeners. Too much nitrogen will cause abundant green leafy growth, but little or no fruit. Too little nitrogen, and the tomato plant will display stunted, pale green to yellow growth. Adequate nitrogen comes in the form of composted steer or chicken manure, worked into the soil in early spring.
Periodically watering with compost tea or seaweed mix will give the developing tomato plants all of the minor nutrients they need.
Insufficient or erratic watering patterns can cause tomatoes to drop off the plant while still immature, or crack when fully ripe. Water with soaker hoses or drip irrigation that provide a slow, steady seepage of water. Soil types all drastically differ in their water retention. Sandy soils may need moisture twice a day during hot weather, whereas clay or loam can go without for a few days.
An early fall frost can completely ruin a ripening crop of tomatoes. The best protection is in the form of frost blankets, available at most garden centers. Frost blankets are a lightweight material rated for certain types of cold. A heavy-duty blanket will protect crops down to 27 F. These should be removed after daytime temperatures rise.
Late spring frosts can not only damage young tomato plants, but also permanently stunt their growth. Wait to plant tomatoes until all danger of frost has passed.