Tomato plants are essentially tropical plants, needing warm days and cool nights. They prefer soil temperatures between 70°F and 75°F. They (drop)blossoms if air temperature is cooler than 55°F or hotter than 90°F and are very sensitive to frost, which blackens and kills them.
Tomatoes need at least 6 to 10 hours of sun daily plus some afternoon shade in really hot climates. They accept almost any kind of soil, as long as it has lots of organic matter in it to help it hold moisture and drain well and is on the acid side (pH 6.0 to 7.0). Add organic matter such as peat moss, chopped leaves or compost to lighten and loosen clay soil or plant tomatoes in raised beds to improve soil drainage. Mix in some all-purpose slow-acting granular fertilizer or a fertilizer product for acid-loving plants when preparing the soil.
Consider The Slant Planting Method
Tomatoes are unique in that when their stem is planted below the surface of the soil roots will form giving the plant a bigger rootball. This is not true for any other vegetables. This means that if you have a seedling that is leggy; long stem before main foliage; then you can plant most of that stem underground. I use a slant method. Instead of digging a very deep hole to accommodate the long stem, I dig a trench 4 or 5 inches deep and lay the plant in the trench with the main foliage part bent up to be out of the ground.
Steps for Transplanting Tomato Seedlings
1.) Water seedlings well 1 to 2 hours prior to planting, to keep their rootballs intact during the transplanting process. If has been dry recently you should water the garden soil the night before putting in the seedlings.
2.) Plant on a cloudy day or in late afternoon or evening to protect seedlings from the hot sun while they cope with transplant shock. The soil is cooler and the relative humidity higher then, reducing moisture stress on the new plants.
3.) Space transplants 1½ to 2½ feet apart. With a trowel dig individual holes a bit deeper than the seedling’s rootball. Deep planting encourages roots to form along the buried stem, increasing the plant’s capacity to take up water and nutrients, resulting in stronger plants.
4.) I add to the hole a handful of compost and some beneficial microbes; no fertilizer.
5.) Gently coax each seedling from its container, set it in its hole and fill in with loose dirt. Press the soil gently around the main stem.
6.) Water transplants generously and then do not allow them to dry out. I add to the water some liquid kelp or seaweed which greatly helps reduce the transplant shock.