Dutch Iris in Zone 5a & 5b
Iris × hollandica
Yes, Dutch iris grows in zones 5a and 5b. Plant it outside in Sep–Nov. For a fall crop, plant out in Sep–Nov.
When to plant Dutch iris in zone 5b
Zones 5a and 5b 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 | ~210 days after direct-sowing |
Spacing: 4 per square foot (square-foot-gardening spacing). Mature height: 1.5-2 ft.
Zone 5b dates sourced from www.johnscheepers.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 Dutch iris for late-summer planting.
Plant alongside it in zone 5b
These go outside within two weeks of Dutch iris in zone 5b, so one planting day can cover them.
- CrocusSep–Nov
- Daffodil (Narcissus)Sep–Nov
- HyacinthSep–Nov
- Ornamental AlliumSep–Nov
Dutch iris grows from a true bulb, not the thick rhizome most gardeners associate with bearded iris, and the flowers look closer to what florists sell than to a typical garden iris: tall, slender stems topped with blue, purple, yellow, or white blooms in early summer.
How Dutch iris fits zone 5's season
Zone 5b's frost-free window runs about 148 days, from May 10 to October 5. Dutch iris goes in during the fall and grows through the winter, so it isn't limited by this window: expect first bloom about 210 days after planting.
Dutch Iris planting windows in every zone
Zone 5b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Bloom |
|---|---|---|---|
| 5a & 5bFall window (your zone) | Not usually | Sep–Nov | ~210 days after direct-sowing |
| 6a & 6bFall window | Not usually | Sep–Nov | ~210 days after direct-sowing |
| 7a & 7bFall window | Not usually | Sep–Nov | ~210 days after direct-sowing |
| 8a & 8bFall window | Not usually | Sep–Nov | ~210 days after direct-sowing |
Bloom dates are about 210 days after the sow or plant-out date.
Good companions
No well-established companions for Dutch iris.
Where to buy Dutch iris 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 Dutch iris" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 5b calendar · Plan your beds in the Garden Designer →
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Growing Dutch Iris in USDA zone 5b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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