Gladiolus / Sword Lily
Gladiolus × hortulanus
description
Gladiolus is a summer corm producing tall flower spikes suited to gardens and containers.
benefits
- Flowering
- Suitable for containers
warnings
- Toxic to cats
- Toxic to dogs
How to care for Gladiolus
sunlight
Gladiolus species grow in open, sunny grasslands, and garden hybrids flower best with the same exposure. Give your plants a bright, unshaded spot.
Full sun
Aim for about 6-8 hours of direct sun daily for sturdy stems and good flowering. In very hot climates, light afternoon shade can protect blooms, but too much shade causes weak growth and fewer flowers.
watering
Water gladiolus deeply while it is actively growing, then let the soil dry more as the foliage finishes. Corms need steady moisture for strong flower spikes, but they rot quickly in soggy soil.
Active growth and flowering
In the ground, water about once or twice a week in dry weather, soaking the root zone rather than sprinkling lightly. In containers, check every 2-4 days and water when the top 1 inch of mix is dry. Heat, wind, small pots, and fast-draining mix make watering more frequent.
After flowering and dormancy
Keep watering lightly, about every 7-10 days if rain is scarce, until the leaves turn yellow. Then stop watering and allow the corms to dry. Stored or overwintering dormant corms should stay dry.
humidity
Preferred humidity
Gladiolus hybrids cope well with ordinary outdoor summer air and average household humidity. Their South African relatives grow through warm seasons with changing rainfall, so steady soil moisture matters more than high humidity.
Acceptable range
Very dry, hot air can make leaf tips crisp and cause developing buds or flower edges to brown, especially on container plants in wind. Give containers a more sheltered spot and water before the compost dries deeply.
- Keep good airflow around leaves and flower spikes to reduce fungal problems.
- In dry spells, water the soil thoroughly in the morning rather than misting the plant.
temperature
Active growth
Winter corm storage
These summer-growing hybrids have roots in warm South African climates. They flower best in steady warmth and are not frost tolerant. Plant or move pots outside once nights stay above about 10°C (50°F). In cold-winter areas, lift corms after the foliage yellows and store them dry, cool, and frost-free.
nutrition
April - August
Feed from active leaf growth until flowering finishes, about every 2-3 weeks with a balanced bulb or flowering-plant fertilizer at roughly half the label strength. Stop feeding once the foliage begins to yellow and while stored corms are dormant.
Phosphorus
Phosphorus supports strong roots and flower development. A balanced fertilizer provides enough without adding extra products.
Potassium
Potassium helps build sturdy stems and good-quality blooms, especially for tall flowering cultivars. Choose a fertilizer intended for flowering plants rather than a high-nitrogen lawn feed.
soil
Loose, well-draining soil
Gladiolus corms need air around their roots and soil that drains promptly after watering, which helps prevent rot. Use a fertile garden loam or potting mix loosened with compost and grit or perlite, rather than dense, wet soil.
pH 6,0 - 6,5
This is slightly acidic soil, a good range for nutrient uptake. Most fresh multipurpose potting mixes suit it well. In the ground, add compost to improve poor soil, but avoid strongly alkaline sites unless you can amend them.