Ornamental Allium in Zone 7a & 7b
Allium spp. (flowering onion)
Yes, ornamental allium grows in zones 7a and 7b. Plant it outside in Sep–Nov. For a fall crop, plant out in Sep–Nov.
When to plant ornamental allium in zone 7b
Zones 7a and 7b share the same average frost dates, so this page covers both.
Method: Direct sow: Direct-sow outside. It doesn't transplant well, or doesn't need the extra time indoors.
| Window | Fall window |
|---|---|
| Start indoors | Not typically started indoors |
| Direct sow / transplant outside | Sep–Nov |
| Estimated bloom | ~195 days after direct-sowing |
Spacing: 5 per square foot (square-foot-gardening spacing). Mature height: 2-3 ft.
Zone 7b dates sourced from www.longfield-gardens.com.
Fall window: the last sowing date is the average first frost minus days to maturity, the method in Purdue Extension's fall garden guide, which lists ornamental allium for late-summer planting.
Plant alongside it in zone 7b
These go outside within two weeks of ornamental allium in zone 7b, so one planting day can cover them.
- CrocusSep–Nov
- Daffodil (Narcissus)Sep–Nov
- Dutch IrisSep–Nov
- HyacinthSep–Nov
Ornamental allium is the flowering relative of the onion you eat, grown for its round, spiky flower heads on tall bare stems rather than for anything edible. It blooms in the awkward late-spring gap after tulips finish and before most perennials are in full swing, which is exactly why gardeners plant it.
How ornamental allium fits zone 7's season
Zone 7b's frost-free window runs about 198 days, from April 10 to October 25. Ornamental allium goes in during the fall and grows through the winter, so it isn't limited by this window: expect first bloom about 195 days after planting.
Ornamental Allium planting windows in every zone
Zone 7b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Bloom |
|---|---|---|---|
| 3a & 3bFall window | Not usually | Sep–Nov | ~195 days after direct-sowing |
| 4a & 4bFall window | Not usually | Sep–Nov | ~195 days after direct-sowing |
| 5a & 5bFall window | Not usually | Sep–Nov | ~195 days after direct-sowing |
| 6a & 6bFall window | Not usually | Sep–Nov | ~195 days after direct-sowing |
| 7a & 7bFall window (your zone) | Not usually | Sep–Nov | ~195 days after direct-sowing |
| 8a & 8bFall window | Not usually | Sep–Nov | ~195 days after direct-sowing |
Bloom dates are about 195 days after the sow or plant-out date.
Good companions
No well-established companions for ornamental allium.
Where to buy ornamental allium bulbs
We haven't vetted bulb/tuber suppliers yet. Our seed-supplier list below doesn't carry these. The growing-guide source cited above is a good starting point for where to buy.
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See it growing
Search YouTube for "growing ornamental allium" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
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Growing Ornamental Allium in USDA zone 7b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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