How to grow Gladiolus

Gladiolus · sword lily

Summer-flowering corm grown for its tall spikes of showy flowers, which open from the base upward and make excellent cut flowers. Plant after the last frost; it blooms 65–100 days after planting. Toxic to cats, dogs and horses, most of all the corms.

Quick facts

Type	Flower
Family	Iridaceae
Light	Full sun
Soil pH	6.5–7
Frost	does not tolerate frost
Soil for sowing	from 10 °C
Germination	14 days
Where it grows	Greenhouse, Open ground

When to plant

Sow straight into the bed after your last spring frost, once the soil has warmed.

In an unheated greenhouse everything moves about three weeks earlier.

Frost dates · When to plant

Care

Greenhouse

Stage	Watering	Temperature	Feeding
Growth	every 7 days	—	balanced (NPK), at the start of the stage; balanced (NPK), 28 days into the stage
Flowering	every 7 days	—	—

Open ground

Stage	Watering	Temperature	Feeding
Growth	every 7 days	—	balanced (NPK), at the start of the stage; balanced (NPK), 28 days into the stage
Flowering	every 7 days	—	—

Growing notes

Light

Needs full sun.

Soil

Moist but well-drained soil of average fertility, pH 6.5–7. Improve very sandy or heavy clay soil with compost.

Care

Plant corms after the last frost once the soil has warmed, 8–13 cm deep (three to four times their diameter) and 10–15 cm apart; plant a new batch every 10–14 days for flowers all summer, the last in time to bloom before frost. Work a complete fertiliser such as 10-10-10 into the soil at planting and side-dress once while the plants grow. Give about 25 mm of water a week and keep watering after flowering while the leaves are green. Stake tall spikes. Except in mild-winter areas, lift the corms when the leaves die back, 6–8 weeks after flowering, dry them for a few days and store them dry and frost-free at about 4–10 °C. Thrips are the most common pest; corm and stem rots are the main diseases.

Pests and diseases of Gladiolus

Sources

Figures checked against these sources.