Early autumn is an ideal time to plant carrot seeds, as the weather is cool but not too cold, allowing the seeds to germinate and grow steadily. Start by selecting a soft, well-prepared patch of ground with loose, fertile soil. Carrots thrive in soil that is free of rocks and debris, as they need room to grow long and straight. Loosen the soil to a depth of at least 12 inches to give the roots ample space.