If you know the regular pink and white cosmos, treat this wildflower the same. It is one of the easiest of all to grow. Seed should be planted spring in the north, spring or fall in light-winter areas. (In the north, a late spring frost can kill your fall-planted cosmos seedlings.) Suphur cosmos (or Orange Cosmos) grows shorter than its more famous pink and white relative, with bushier plants. Bloom will begin in midsummer and continue until frost. This wildflower is one of the best for pressing. When weeding in spring, if you recognize ragweed, beware...the foliage of this species is almost identical.