Many parts of the United States don't have long enough warm seasons to start all garden plants directly outside in the garden bed. Some of the most useful, and favored, vegetables to grow are easy to get started from seed, and most people start tomatoes indoors then transplant them outside once all danger of frosts have passed.
If you live in an area that doesn't have problems with late frosts, you can start your outdoor tomato beds from seeds and skip the transplanting steps most people take. Tomatoes germinate at 75 to 80 degrees, and in some parts of the country this means they can be planted outside as early as mid-March.
Prepare the outdoor tomato seed bed by turning over and tilling the ground. If possible, do this in late autumn so the soil is able to settle during the winter.
Remove all rocks, weeds and other debris from the planting area.
Mix in quality potting soil or mature compost. Spread several inches over the turned soil, then mix it into the bed. Don't add too much nitrogen or else you'll get very leafy tomato plants that don't bear much fruit.
Gently sprinkle the newly turned bed with water until it is fully moistened.
Sprinkle your tomato seeds evenly across the new garden bed, trying to keep them at least 6 to 12 inches apart.
Sprinkle or spread a mixture of soil and compost over the seeds until they're covered 1/4 to 1/2 inch.
Sprinkle water gently over the newly planted seeds--enough to fully moisten the soil without moving it or washing it away.
Water the new tomato seed bed at least once each day, and twice on hot or windy days, until the seedlings begin to sprout.
As the tomato plants grow larger, gradually reduce the amount of water enough each week to ensure at least 8 to 10 inches of the soil depth in the tomato bed is moist.