How to Grow Gladiolus
Gladiolus × hybridus
Majestic summer spikes loaded with florets — the classic cut flower grown from corms planted after frost.
By the Plants by Zone Editorial Team · Reviewed June 1, 2026
About gladiolus
Gladiolus are tall, dramatic summer-flowering plants grown from corms — swollen underground stem bases that are planted in spring and, in cold zones, lifted in fall for storage. Each corm sends up a rigid spike bearing 15–20 florets that open in sequence from the base upward over about two weeks, making them among the longest-lasting cut flowers. Staggered plantings every two weeks through late spring produce a continuous parade of bloom from midsummer until frost in colors spanning pure white through deep burgundy, lavender, salmon, and bicolors.
When to plant and harvest gladiolus
Timing is relative to your frost dates. Find your USDA zone for exact dates, or browse the month-by-month calendars.
Start seeds indoors
Not needed; corms are planted directly outdoors
Transplant outdoors
Not applicable — grown from corms planted directly in the ground
Direct sow
Plant corms 2–4 weeks after last frost, once soil reaches 55°F; stagger plantings every 2 weeks through early summer for continuous bloom
Harvest
Midsummer through fall, 70–90 days after each staggered planting
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How to grow gladiolus step by step
- 1
After the last frost, once soil has reached at least 55°F, plant corms 4–6 in deep, flat side down and pointed side up, 6–8 in apart in a sunny, well-drained spot.
- 2
Stagger additional plantings every 2 weeks through late spring or early summer so the blooms keep coming rather than all arriving at once.
- 3
Water 1 inch per week and mulch around the corms to retain moisture and keep the soil cool.
- 4
Stake tall varieties individually at planting time, or plant in dense rows of 12 or more so the spikes support each other.
- 5
For cut flowers, slice spikes when the lowest 1–2 florets just show color; they will open fully indoors over the next week.
- 6
In zones 6 and colder, after the first hard frost blackens the foliage, carefully dig the corms, let them dry for a week, and store in a cool, dry location over winter.
Common problems growing gladiolus
⚠ Corms rotting before sprouting
Almost always caused by planting in cold (below 55°F) or waterlogged soil — wait for warm weather and amend heavy clay with grit or grow in a raised bed.
⚠ Thrips (silvery streaking and distorted petals)
The most common gladiolus pest; dust corms with diatomaceous earth before planting, and spray affected foliage with neem oil or insecticidal soap at first sign; severely infested corms should be discarded.
⚠ Spikes flopping over
Tall varieties need individual stakes or the support of dense planting; also plant corms 6 in deep rather than 4 in for better anchorage in loose soil.
⚠ Florets failing to open on the spike
Either cut too late — once two-thirds of the florets have already opened, the rest won't — or the vase water wasn't changed; cut early, recut the stem under water, and refresh every two days.
✓ Good companions for gladiolus
✗ Keep away from
🧺 Harvesting gladiolus
Cut gladiolus spikes in the early morning when the lowest one or two florets have just begun to unfurl — the rest will open in the vase over the following 10–14 days. Make a diagonal cut low on the stem, leaving at least four or five leaves on the plant so the corm can rebuild energy for replanting. Remove individual spent florets from the base as the spike opens upward, and recut the stem every two days. In zones where corms overwinter in the ground, leave the foliage intact until it yellows naturally so the corm fattens for the next season.
Gladiolus: frequently asked questions
When should you plant gladiolus?＋
In most regions you plant corms 2–4 weeks after last frost, once soil reaches 55°F; stagger plantings every 2 weeks through early summer for continuous bloom. Timing is relative to your last frost, so find your USDA hardiness zone for the exact planting dates where you live.
Do I need to dig gladiolus corms every year?＋
Only in zones 3–6, where the ground freezes solid. In zones 7–10, the corms are winter-hardy and can stay in the ground. In cold zones, dig them after frost kills the tops, dry them for a week in a warm, airy spot, dust with a fungicide powder, and store in a net bag or paper bag in a cool, frost-free location until spring.
Why are my gladiolus not blooming?＋
The most common reasons are: corms were planted too shallow (less than 4 in) and fell over before spiking; heavy shade reduced energy; or the corms are old and undersized — gladiolus produce smaller "cormels" around the base each year, and only corms at least ¾–1 in across reliably bloom. Grade your stored corms and plant only the largest.
Sources & review
Written and maintained by the Plants by Zone Editorial Team. Planting times are based on USDA hardiness zones and NOAA frost-date normals, with care guidance drawn from Cooperative Extension sources. Last reviewed June 1, 2026.
USDA Plant Hardiness Zone MapNOAA U.S. climate normalsCooperative Extension
Grow gladiolus in your zone
See exactly when to plant and what else to grow alongside gladiolus, tailored to your USDA hardiness zone.
