How-to Guide
How to Grow Gladiolus
The short answer
Gladiolus grow from corms planted in spring. Clemson Extension says to set corms 3 to 6 inches deep depending on their size, 2 to 3 inches apart in the row, in full sun and well-drained, moist soil. Because each corm sends up one flower spike, stagger plantings about a week apart to stretch the bloom season across the summer.
In climates where they will not overwinter, dig the corms after the tops die but before a hard freeze, let them dry for 2 to 3 weeks, and store them at 35 to 45 F in a well-ventilated place (Clemson).
When and how deep to plant
- 1Plant in spring — Start after frost danger, and make succession plantings a week apart for continuous blooms (Clemson).
- 2Depth matches corm size — 3 to 6 inches deep depending on size — big corms deeper, small ones shallower — and 2 to 3 inches apart in the row.
- 3Plan for support — Tall spikes in loose soil lean; planting at the deeper end of the range and hilling soil around stems helps keep them upright.
Sun, soil, and water
Full sun and well-drained but moist soil are the requirements. Keep plants evenly watered while the flower spikes are developing — drought during spike formation shows up directly in the bloom.
Digging and storing corms
- 1Dig after tops die — Lift corms after foliage dies down but before a hard freeze (Clemson).
- 2Cure 2-3 weeks — Dry the corms for 2 to 3 weeks in a ventilated spot before storage; skipping the cure invites rot.
- 3Store cold and airy — 35 to 45 F in a well-ventilated area — mesh bags or old onion sacks work well. Discard soft or diseased corms before they spread trouble.
✔ When you clean cured corms you will find a fresh new corm formed on top of the old shriveled one. Keep the plump new corm; the spent old one below it can be broken off and discarded.
After-bloom care
Cut spent flower spikes so energy goes into the new corm, but leave as much foliage as possible until it yellows — the leaves are rebuilding next year's corm. In mild regions where corms stay in the ground, this after-bloom foliage period is what determines the size of next summer's spikes.
Sources
Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.
- Clemson Cooperative Extension HGIC — Summer- and Fall-Flowering Bulbs — Gladiolus planted in spring, staggered weekly; 3-6 inches deep by corm size, 2-3 inches apart; full sun, well-drained moist soil; dig after tops die before hard freeze; dry 2-3 weeks; store 35-45 F well-ventilated