Grown from corms, gladiolus — available from miniature to giant — are favored for their large, showy blossoms and classic, spiky stems.
Sunlight: Full sun
Maturity: 70-95 days from corm to flower
Height: 2 to 5 feet
Spacing: 4 to 6 inches apart in all directions
Gladiolus with their dramatic sword-like leaves have sturdy flowering stems that grow up to 5 feet tall. The trumpet-shaped flowers come in shades of almost every color and are the perfect backdrop to garden beds. Home flower gardeners particularly enjoy growing gladiolus for long-lasting cuttings and floral bouquets.
Summer bulbs, like “glads,” are the perfect addition to the flower garden. They combine beautifully with annuals and perennials, offering a uniqueness that completes the landscape. Try planting over several weeks in spring to create brilliant displays of color throughout the summer months. Smaller varieties can be grown in containers where space is limited. Tender perennial often grown as an annual.
Tip: For best results, take cuttings when at least 3 of the “florets” on the stem have opened. They will continue to open in the vase.
Gladiolas require full sun and regular water during growth and bloom. They should be planted in well-drained soil, rich in organic matter as soon as the ground is warm enough to work in the spring.
Prior to planting work a couple shovelfuls of organic compost into the garden (watch 6 Tips for Growing Great Flowers – video). This helps condition the soil, which improves drainage and will also increase the ability of lighter soils to hold water and nutrients.
Provide protection from the wind, if possible.
How to Plant:
Gladiolus corms should be set four times deeper in the soil than their height. Large corms should be 6 inches apart; small ones 4 inches. Add bone meal, rock phosphate or organic bulb food to the planting hole and mix with the soil. Place corms in the hole and cover with soil, tamping firmly. After planting, top-dress the site with 2-4 inches of organic mulch to help retain moisture and deter weeds.
Tip: Once the flower spikes start to show work a bloom boosting fertilizer into the soil every few weeks for bigger, bolder blooms.
If you live in USDA zones 6 or less, the corms should be dug up in the fall and stored. Do NOT allow corms to freeze. When the foliage begins to dry, withhold water. Once they are completely dry, dig the corms and remove the faded foliage. Dust with an organic fungicide and store in a cool dry place. Plant again in spring after the soil warms.
Insects and Disease:
Gladiolas are susceptible to a number of garden pests. To minimize many of these pest problems, always start with sound corms. Toss any that don’t look right or feel soft and crumbly.
- Remove weeds and other garden debris to eliminate alternate hosts.
- Discard severely infested plants by securely bagging and putting in the trash.
- Release commercially available beneficial insects to attack and destroy insect pests.
- Spot treat pest problem areas with neem oil or other organic pesticide.
Foliage and flowers are susceptible to several fungal and bacterial diseases, such as gray mold, scab and rust, which can disfigure the leaves under severe infestations. To reduce plant diseases common to gladioli:
- Avoid overhead watering whenever possible
- Properly space plants to improve air circulation
- Apply copper or sulfur sprays to prevent further infection
“Glads” are also host to several viruses. Symptoms include spindly, stunted growth, yellow foliage and leaves marked with ring spots and pale or dead areas. There is no cure once plants are infected; pull and destroy infected plants.