Be sure that you choose disease and insect free plants with no fruit. If a tomato plant is already putting energy into forming fruit it will not do well forming roots when it is transplanted. Buy good quality; larger is not better.
Add an organic soil amendment to the area where the tomatoes will grow. Now look at the plants. Remove all stems and leaves on the stem except for three or four sturdy stems at the top of the plants. Plant the tomato plants deeply with only those top stems above the soil surface.
The reason for this is that every bit of stem that is underground will sprout roots to help your developing tomato plant. You will get a nicely developed, extensive root system on the plant.
|Not Planted Deeply Enough|