How to Plant Hardy Gladiolus

Hardy gladiolus are compact, 18–24 inch glads that can stay in the ground over winter. Plant the bulbs in spring, 4–6 inches deep and 4–6 inches apart, then leave them in place under a thick winter mulch.

When to plant
Spring, after danger of frost has passed
Depth
4–6 inches (10–16 cm) deep, pointed end up
Spacing
4–6 inches apart
Sun
Full sun, at least 6 hours
Water
About 1 inch a week; keep watering after flowering while the leaves are green
Soil
Fertile and well-drained, pH 6.0–6.5

Step by step

  1. Choose a sunny, well-drained spot, ideally where the bulbs can stay undisturbed for several years.
  2. Loosen the soil and mix in compost if it is heavy clay or very sandy.
  3. Set each bulb pointed end up, 4–6 inches deep and 4–6 inches apart. Groups of five or more make the best show.
  4. Cover, firm the soil and water thoroughly.
  5. Spread 2–4 inches of mulch once shoots appear.
  6. Most hardy glads stand without support. In a windy spot, add a short stake before the flower spike emerges.

After bloom

Cut off flower stems as they fade. Let the foliage die back on its own; it feeds the bulb. Leave the bulbs in the ground. When the ground starts to freeze, cover the bed with 4–6 inches of straw or shredded leaves; pull it back in early spring. Zone 5 is the edge of their range. If your winters are hard or your soil stays wet, lift the bulbs after the leaves die back instead, store them dry and frost-free at 35–45°F, and replant in spring. Clumps form small new bulbs; separate them while dormant.
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