Mistimed Planting
Planting sunflowers too early in cold, wet soil or too late in scorching heat can stunt growth and delay blooms. I’ve rushed to sow seeds at the first hint of spring frost and ended up with moldy, rot-prone seeds sitting in saturated ground! Conversely, sowing in mid-summer can leave seedlings gasping in 90°F soil that bakes on the surface.
Aim to plant sunflower seeds one to two weeks after your last spring frost, once soil temperatures hover above 50°F. In cooler climates, starting indoors in peat pots lets you transplant sturdy seedlings when conditions improve. For hot regions, consider a late-summer sowing that matures in the mild days of early fall.