Carrot seeds require warm, moist soil to germinate and thrive. In areas where the weather is a bit dry during the spring and summer planting season, providing an ideal environment for the seeds can prove difficult. Covering the garden bed with a layer of plastic mulch is one way to keep the seeds warm and and damp while they grow. Plastic mulch also tends to block weed growth, which can be helpful when the delicate seedlings are just forming.
Till the garden bed with a hand tiller, working the soil eight to nine inches deep. Remove all stones, roots and other debris from the soil; anything that gets in the way of the carrots could cause them to grow crookedly.
Scatter the carrot seeds in rows spaced 12 to 18 inches apart. Cover the seeds with about 1/2 inch of tilled soil.
Water the seeds gently, but thoroughly. Make sure the soil in the garden bed is wet but that no puddles of standing water form on the surface of the dirt.
Bury the loose end of the roll of plastic mulch at the end of the first row. Make sure that it is sunk in deep enough that it won't be pulled up by the wind (about four to six inches). Unroll the plastic mulch over the row.
Cut off the sheet of mulch, leaving about a six-inch tail, and bury the tail in the dirt at the other end of the row. Repeat the process until all rows are covered.