Any time between February and June (but after danger of frost is past) bury them 3 to 4 inches deep in porous soil directly in the garden or in containers. Eight weeks after planting, flower stalks begin shooting up, and you’ll be delighted by blossoms for the next couple of months. The color-soaked hybrids prefer a well-drained, porous soil. Sandy soils are simpatico if you add fertilizer; clay soils can be tricky. Excessive nitrogen will encourage a bounty of leaves and long stems, squelching bud production. In a fertile soil, no further food is needed.