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Ornamental allium from seed

Q: I have some beautiful seed heads of Allium cristophii drying in the garden. Can you tell me how to start these plants from seed, and how long it takes for seedlings to reach blooming size?

Karen Welty-Wolf, Durham, NC

Allium seeds may be slow to germinate. Give them periods of cold temperatures followed by periods of warm temperatures to break dormancy. Photo/Illustration: Jennifer Blume

A: Bob Stewart, owner of Arrowhead Alpines Nursery in Fowlerville, Michigan, replies: Allium cristophii is one of the more difficult Allium species to germinate. The seed needs alternating periods of cold temperatures (about 120 days at 40˚F) and warm temperatures (about 90 days at 70˚F), starting with the cold temperatures. Watch the pots closely during the cold cycle, as this is when germination is most likely to occur. Dry-stored seed generally does not germinate until the second or third year after sowing. Very fresh or very old seed may germinate the first year. This is either because the seeds’ germination inhibitors have not fully developed or because the inhibitors have degraded during extended dry-storage at room temperature.

Sow the seeds directly on the surface of a soilless mix and cover them with a layer of chick starter grit (a crushed granite product available at feed stores) to help keep moisture constant and prevent moss and weeds from overgrowing the seed pot. Using the chick grit starter also goes a long way in preventing damping-off problems. To provide a cold period for the seeds, cover the pot with a zip-top bag and place it in the vegetable drawer in your refrigerator.

Keep your seed pot moist but do not overwater it. You want to strike a balance by not letting the pot dry out completely, yet not letting it get soggy and moss-covered. If it does, carefully cut off the moss layer, leaving the seed behind, and top-dress the pot with more chick starter grit.

There are many formulas for success, but the most important ingredient is patience. The only thing to do with some species, like A. cristophii, is to sow and wait for a couple of years. Keep the seed pot for at least four years, and before you decide to throw it away, dig around and find a seed and cut it in half. If it hasn’t rotted, the other seeds will germinate eventually. Once A. cristophii seeds do germinate, the seedlings form a small bulblet the first season, and should flower in three to five more years. For more information on seed germination, I highly recommend Seed Germination Theory and Practice by Norm C. Deno (139 Lenor Drive, State College, PA 16801).

From Fine Gardening 80, pp. 70