Here are the two main methods for getting your tomato
plants in the ground. The trench method is best for tall, leggy seedlings and for cooler climates. The vertical method allows you to put the plant's roots where they can take advantage of a larger reservoir of soil moisture, which is helpful in areas with hot, arid growing seasons.
First, pinch any yellowing or dying leaves off the tomato plant and lay the whole it horizontally in a shallow trench. Cover the stem with two or three inches of soil and bring just the top cluster of leaves above the surface.
An advantage to trenching in cool regions is that the roots are only a few inches from the warmest part of the soil and this encourages more growth from the heat-loving tomato plants.
Once you've prepped for planting as outlined in Transplanting Tomatoes
, carefully take the tomato plant out of its container. Cup your hand around the rootball, and disturb the soil covering the roots as little as possible. Pinch off any yellow lower leaves, leaving just the green ones.
Wrap a newspaper or paperboard cutworm collar around the stem where it enters the soil, and lay the plant horizontally in the trench. Quickly cover the roots and stem up two to three inches of soil, leaving just the leafy top exposed. Don't try to bend the top of the plant up -- just push a little pillow of soil underneath to support it. Mother Nature will see that it grows in the right direction.
Space the plants so that the top clusters of leaves showing above the surface are 36 to 48 inches apart. You can put them 10 to 24 inches apart if you plan on staking or caging them. Leave enough space - two or three feet - between the rows so you can cultivate and later get around the plants to prune and harvest.
Give the area a good soaking after the seedlings are in place.
If you wait until later to stake or cage your trenched plants, you may forget where the stems are buried, and risk damaging them. For this reason it's best to stake or cage your trench-planted tomatoes right away. If your garden is in a windy spot, put the stakes on the side of the plants opposite the prevailing winds. If the wind comes from the west, for example, place the stakes on the east side of the plants. Then, when the wind blows the plant will be held against the stake. Otherwise, if the wind pushes the plant against the string or ties holding it to the stake, the stem might suffer damage.
Vertical Planting Technique
With this method you prepare a hole for each of your tomato plants and set them in vertically. You can plant them to the same level they were growing in their container, or pinch off yellowing lower leaves and plant the seedlings deeper.
Leggy seedlings gain the most advantage from deep, vertical planting once the soil temperature reaches 60° F. Space plants 18 to 24 inches apart if you plan on staking or caging them. If you let them to sprawl, give them more room -- 36 to 48 inches -- and space rows three feet apart.