Hyacinths are grown as far north as the Ohio Valley and up the eastern coastal areas into New England (Zone 5). Protected by a layer of mulch, they are hardy where winter temperatures seldom fall below -5 to-10°F. In regions colder than this, these bulbs should be dug up in the fall, stored in a dry, cool place over the winter and replanted in the early spring.
Locating And Planting Hyacinth
Plant hyacinth bulbs in October before the ground freezes. Choose a site that enjoys full sun or partial shade in the spring. Like most bulbs, hyacinths require soil that drains well. They do poorly in wet, clayey soils. Build hyacinth beds higher than the surrounding soil surface or add lots of organic matter (such as compost, rotted manure, leaf mold, peat moss) to the soil to promote good drainage. The soil should be slightly acidic (pH 6.0 to 6.4) and can be on the sandy side. If possible, loosen the soil 1 foot deep when preparing the bed for planting because hyacinth bulbs develop very deep roots.
Plant hyacinth bulbs 5 to 6 inches deep and 6 to 8 inches apart. Measure the depth from the bottom of the hole. Be sure all bulbs in the group are planted at the same depth to assure that they bloom at the same time. Point the bulbs' growing tips right-side-up and press their rounded bottoms into the soil, using a slight twisting motion to assure good soil contact for the root plate. Fill in the hole and cover the bed with mulch to protect it from heaving during winter temperature fluctuations.