Gladiolus in Zone 4a & 4b
Gladiolus spp.
When to plant gladiolus in zone 4b
Zones 4a and 4b share the same average frost dates in our data, so this page covers both.
Method: Direct sow: Direct-sow outside. Gladiolus doesn't transplant well, or doesn't need the extra time indoors.
| Start indoors | Not typically started indoors |
|---|---|
| Direct sow / transplant outside | May 1–May 8 |
| Estimated bloom | Jul 30–Aug 6 (~90 days after direct-sowing) |
Spacing: 2 per square foot (square-foot-gardening spacing). Mature height: 2-4 ft.
Gladiolus is the one bulb crop in this group that runs on the opposite calendar from tulips, daffodils, and the rest. It's planted in spring, not fall, and blooms the same summer instead of waiting through winter, sending up 2- to 4-foot spikes lined with ruffled, trumpet-shaped flowers in almost any color you can order.
How gladiolus fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Gladiolus needs about 90 days from sowing to first harvest.
Good companions
No standout companions recorded yet for Gladiolus.
Where to buy gladiolus 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.
See it growing
Search YouTube for "growing gladiolus" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 4b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →
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Growing Gladiolus in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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