Cover with a one-eighth inch layer of fine soil. Germination will take from five to 10 days. The seeds and young seedlings can take very light frosts, but might die after a hard freeze. When the first true leaves appear, thin the sunflowers to stand a couple of feet apart. Stake tall plants to help hold up the seed head.
Sunflowers thrive in hot, dry weather, and tolerate droughts.
But the benefit from large quantities of water applied as deep soakings. The sunflower is a very vigorous growing plant, reaching six feet in four or five months. To keep up with this growth, a booster application of organic fertilizer or compost is recommended when the flower head begins to appear. The sunflower has few enemies to contend with. Most common are the stem borer and stem maggot, rust and powdery mildew.