Sow seed in a light, well-drained soil. Seeds need air as well as water to germinate. Sow no deeper than 2 to 3 times the diameter or length of the seed. Very fine seed should be sown on the surface. Most seed requires constant moisture to germinate. Also pay strict attention to temperature requirements for different varieties. Failures in seed germination are almost always caused by improper attention to cultural requirements. The most common causes of seed failure are sowing the seed in cold, soggy soil, heavily waterlogged soil, cold soil, or in soil that has been allowed to dry out. For starting seed indoors, use of seed starting soil is recommended.