Gladiolus Growing Guide

Gladiolus

Crop Rotation Group

Miscellaneous 

Soil

Fertile soil with excellent drainage.

Position

Full sun.

Frost tolerant

Varies. A few small species of gladiolus can survive winter temperatures to 15F (-9C), but large-flowered gladioli should not be considered winter hardy.

Feeding

Topdress with rich compost in early summer, after new growth appears.

Companions

Zinnia and Dahlia. Tall gladiolus make great plants for the back of a sunny bed. When grown primarily for cutting purposes, gladioli are often grown in garden beds so the corms can easily be lifted and stored through the winter.

Spacing

Single Plants: 11" (30cm) each way (minimum)
Rows: 7" (20cm) with 9" (25cm) row gap (minimum)

Sow and Plant

Gladioli are sold as dormant corms. Cultivate the soil to at least 12in (30cm) deep, and digging in a balanced organic fertilizer and a generously amount of compost. Plant the corms 4in (8cm) deep. Plant gladioli in groups, two weeks apart, to insure a long bloom time. Allow 12in (30cm) between tall gladioli. Small dwarf varieties can be planted 8in (20cm) apart.
Our Garden Planner can produce a personalized calendar of when to sow, plant and harvest for your area.

Notes

Tall gladioli often benefit from staking. The open florets often face the direction that offers the brightest sun. The color range is huge, and includes many bi-colors.

Harvesting

Cut gladioli for arrangements when one third of the florets are open. The rest will continue to open indoors. As the flowers fade in the garden, trim them off with scissors or pruning shears. In fall, lift the corms before the first freeze and let them dry in a warm place for two weeks. Trim the cured corms and store in open boxes in a cool place through winter.

Troubleshooting

Gladioli have few serious problems with insects and diseases. Discard corms that show signs of rotting, as well as those from stunted plants, which may be infected with any of several viruses.

Planting and Harvesting Calendar

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Pests which Affect Gladiolus