Here are some general guidelines on setting your transplants into the garden.
Following is a step by step guide to transplanting tomatoes. These guidelines can be used for any plant, with one exception: All plants other than tomatoes should be set in the ground at the same depth that they were growing in the container.
Begin by soaking the rootball in a dilute fertilizer solution. Set the pots in a waterproof tray, and pour in a half-strength, lukewarm solution of fertilizer (preferably fish emulsion- or seaweed-based) to a depth of about one inch. The moisture will help keep the rootball intact, and the fertilizer will get the plants off to a good start. Let the plants soak for at least half an hour, while you assemble your materials and prepare the planting area.
Next, dig the planting holes. It's a good idea to use a yardstick or measuring tape to be sure you're spacing plants properly. Avoid the temptation to squeeze in a few extra plants. Pour some water into the planting holes to moisten the soil.
Remove a plant from its container by placing one hand over the soil surface, so that the plant is positioned between your thumb and fingers. Turn the pot upside down, and rap gently on the bottom of the container. Hopefully, the root ball will slide right out. If it doesn?t, try squeezing the container, rapping harder on the bottom, or, as a last resort, cutting away the container.
If the plant is growing in a peat pot, there's no need to remove the pot. However, it's a good idea to tear away the top rim of the peat pot down to the soil line. If the peat pot is exposed to air, it can wick moisture away from the root ball.
Set the plant in the hole, and add soil around the rootball, gently firming the soil as you go to eliminate air pockets. Once the hole is filled, create a shallow well around the plant, so that water will gather there instead of immediately running off.
Protect new transplants against cutworms. These common pests chew young stems right at ground level. One easy method is to loosely wrap a strip of newspaper around the stems. The paper should span from one to two inches above the soil surface to an inch or two below--this is the cutworm's territory. A collar made from several thicknesses of newspaper will last long enough for the stems to grow large enough to discourage cutworms. Don't wrap collars too tightly, and don't use plastic.
Water the plants gently but thoroughly. You'll need to check the plants frequently, and water as necessary to keep soil moist down to the depth of the rootball.
Tomatoes are one of the few plants that can--and should--be planted deeper than their original soil line. Unlike most plants, tomatoes will develop roots along their buried stems. These additional roots will help anchor the large plants and will allow the plant to take in the nutrients and water it needs to product a good crop.
If you have a stocky, compact plant, bury the stem up to the first leaf.
If your plants are tall and leggy, pinch off the bottom few leaves, then set the plant sideways into a trench, carefully bending the top of the plant upward.