Northern climates, where springs are relatively cool, suit snowdrops best. Common snowdrops grow almost everywhere in the U.S. where there are "winters". Only in the far North, northern Vermont, New Hampshire and Maine (zone 3), are they discouraged by the cold. Because they need a winter cold temperature of 20°F or lower to stimulate bloom, they won't do well much below Georgia.
Locating And Planting Snowdrops
Plant snowdrops in the fall, 4 to 8 weeks before the ground freezes. Choose a sunny to partially shaded location. Like most bulbs, snowdrops do poorly in wet, clayey soils. To improve soil drainage, build their beds higher than the surrounding soil surface, and add lots of organic matter (such as chopped leaves or peat moss) to the soil. It should be slightly acidic to slightly alkaline (pH 6.5 to 7.5). If possible, loosen the soil 1 foot deep when preparing the bed for planting.
Plant snowdrop bulbs 3 inches deep and 3 inches apart. Measure the depth from the bottom of the hole. Aim the bulbs' pointed growing tips up and press their rounded bottoms into the soil, using a slight twisting motion to assure good soil contact for the root plate. Cover the bed with mulch to protect it from heaving over the winter.