How to Grow Hyacinths

Hyacinths are grown for their dense, waxy flower spikes and a fragrance strong enough to scent a room. Each bulb normally sends up one spike in mid-spring, usually in bloom at the same time as daffodils, and it lasts two to three weeks. They are easy to grow, but they are less permanent than daffodils, and they need a real winter to bloom properly.

Where hyacinths grow best

The garden hyacinth (Hyacinthus orientalis) is native to the eastern Mediterranean and southern Turkey. NC State rates it for zones 4 to 8. In the cool North it behaves as a perennial. Nebraska Extension warns that high soil temperatures can make them short-lived even on the Plains, and in the Deep South they get too little winter cold to bloom well. Texas A&M AgriLife says San Antonio winters simply aren’t cold enough. Along the coast of South Carolina, Clemson treats them as a one-season flower grown from refrigerated bulbs.

Roman hyacinths (H. orientalis albulus) are the exception for southern gardeners. Their flowers are smaller and looser, but Clemson finds they persist better than the big Dutch hybrids.

Choosing a site

Full sun gives the tallest, straightest spikes, South Dakota State notes, though hyacinths tolerate part shade. More important is drainage: hyacinths need loose, organically rich soil that doesn’t stay wet, or the bulbs rot. Clemson keeps soil pH for bulbs between 6 and 7. If your soil is heavy, work 2 to 3 inches of compost or shredded pine bark into the bed 10 to 12 inches deep, or plant in a raised bed. Avoid beds watered by lawn sprinklers all summer.

Plant them where you’ll smell them: along a walk, near a door or under a window. They look best in groups of one color rather than dotted singly.

How to plant hyacinth bulbs

Wait until the soil at planting depth stays below about 60°F; see when to plant hyacinths and the dates for your zone above. Until then, keep bulbs somewhere cool and dry, away from ripening fruit.

1. Put on gloves. The sap can irritate skin, and NC State notes the bulb holds the highest concentration of irritating compounds.
2. Dig the bed or hole so the base of the bulb sits about 6 inches deep. Nebraska uses 6 inches; Clemson gives 4 to 6.
3. Space bulbs 3 to 6 inches apart (Clemson) for a dense show, or up to 8 inches (Nebraska).
4. Set each bulb pointed end up, cover, and firm the soil.
5. Water thoroughly. Keep the soil moist while the roots establish, and in dry falls water deeply once a week until the ground freezes.
6. Once the ground freezes, cover the bed with 2 to 3 inches of mulch to moderate soil temperature swings.

Care through the season

Hyacinths need little attention. Water during a dry spring to keep the flowers going. For bulbs you plan to keep, Clemson suggests a slow-release complete fertilizer at planting in fall, or 1 to 2 pounds of 10-10-10 per 100 square feet in fall and again as shoots emerge. Bulbs grown for one season need no fertilizer.

Cut off spent spikes as soon as they fade. Leave the leaves in place until they yellow, then remove them. Taper off watering after bloom as the bulbs go dormant.

Why hyacinth flowers shrink

A first-year hyacinth is a showpiece. In later years the bulb splits into smaller bulbs, and the spikes become shorter, looser and more widely spaced. This is normal. NC State notes that outdoor hyacinths give smaller, more widely spaced flowers each year. For a formal bed with full-size spikes, Clemson suggests digging the bulbs after the leaves wither, storing them dry and replanting them in fall, or simply buying fresh bulbs each fall. In an informal garden, the looser spikes of older plantings have their own charm.

Problems

• Short, stunted spikes. Not enough chilling. Buy pre-chilled bulbs or refrigerate them before planting in warm areas.
• Bulb rot. Wet, poorly drained soil. Improve drainage or use a raised bed.
• Skin irritation. Wear gloves when handling bulbs.
• Decline after a few years. Normal splitting of the bulbs. Replant or replace.

Squirrels and chipmunks generally leave hyacinths alone, because the bulbs are toxic to them. Wisconsin Extension suggests planting hyacinths and daffodils where rodents dig up tulips and crocus.

Forcing hyacinths indoors

Hyacinths are among the easiest bulbs to force. Rutgers fits three bulbs in a 6-inch pot, with the tips at the soil surface. Keep the pots at 35 to 48°F for at least 12 to 13 weeks. Once roots fill the pot and short shoots appear, bring them into a bright room at 55 to 60°F; they flower three to four weeks later. Forced bulbs seldom rebloom well outdoors, so most gardeners discard them afterward. Florist hyacinths, NC State notes, are not suited to growing long-term as houseplants.