Learn How To Plant, Care and Grow Impressive Gladiolus Flowers

When to Plant Gladiolus Corms

• The best time to plant gladiolus corms is in the spring. They may be started indoors as early as a month before the average last frost date (for earlier blooms) or planted directly in the ground after the danger of frost has passed and the soil has warmed to at least 55°F (13°C).
• Since Gladioli bloom only once each season for about 2 weeks, you may plant Gladiolus corms every two weeks from the last frost date until early summer to extend their colorful show.
• It typically takes 10-12 weeks from planting to flowering, depending on weather conditions and variety.
• The last planting should be no later than early July to give the corms enough time to develop and mature before frost.

Where to Plant Gladiolus Corms

• Best flowering occurs in full sun in humusy, medium moisture, well-drained soils.
• Gladioli adapt to a wide range of soils except for clay.
• Provide consistent moisture during the growing season, and do not allow the soil to dry out. Lack of water may cause shorter spikes, smaller florets, and smaller corms for the next season. After flowering, you may reduce watering.
• Gladiolus flowers look wonderful in beds and borders or containers.
• In addition to their garden uses, Gladioli are also very important as cut flowers.

How to Plant Gladiolus Corms

• Dig over the soil to loosen it and fork in well-rotted manure or garden compost to help retain moisture, improve drainage, and add some nutrition.
• Plant large corms 4-6 in. deep (10-15 cm), medium-sized corms 3-4 in. deep (7-10 cm), and small corms 2-3 in. deep (5-7 cm).
• Corms may be spaced 5 in. apart (12 cm). Gladioli are often planted too far apart, so they do not show their best. Planting them close together will also enable them to hold each other and reduce the need for staking.
• Plant in groups of 7 minimum for best visual impact.
• Set the Gladiolus corm with the sprout facing up. Cover the corm with soil and water as needed. Mulch to keep down weeds and conserve soil moisture.
• In containers, place the corms closer.

Gladiolus Care during the growing season

• Provide consistent moisture during the growing season, and do not allow the soil to dry out.
• Feed with a liquid fertilizer high in potassium to promote flowering when flower spikes emerge.
• Keep the soil surface free from weeds.

Cutting Gladiolus Flower Spikes

• To enjoy the best of your Gladiolus flowers, pick them when the first florets are beginning to open. The remaining florets will open in time.
• Cut the spikes in the early morning or evening for optimum freshness – make sure at least four leaves are left on the plant to allow corm development.
• Place the flowers in warm water to keep the florets from wilting. Leave them in a cool, dark place for several hours before composing your bouquet. This will help the flowers harden up and last longer.
• Change the water daily, and give stems a fresh cut to extend their life.

Gladiolus Fall Care

• Many Gladiolus species and hybrids are winter hardy in zones 8-11, meaning their corms can be left in the ground year-round in those areas. However, if you live in a colder area and want to save your corms for next spring, you may dig them up before the first frost and store them over winter before replanting them next spring. Not sure about your growing zone? Check here.
• Corms are usually ready for digging about 6 weeks after they have bloomed. Their leaves should be yellowing and dying back.
• Dig your corms when the soil is dry. Wash off the soil and cut the tops off just above the corms. Place them in a light, warm, well-ventilated place for 2-3 weeks to cure (to eliminate excess moisture).
• After the corms are cured, separate the new corm from the old dried corm. These two parts should snap apart easily by hand and leave a clean scar on the new corm. Remove the loose husks, leaving the wrapper husks intact. The small cormels can be saved and planted the following year, but it will take 2-3 years to produce a blooming-size corm from them.
• Before putting the corms into storage, dust them with an insecticide for thrip control. Place the corms in trays, paper bags, mesh onion bags, or even nylon stockings for winter storage.
• Store them in a dry, cool, frost-free place where the temperature remains between 35-40 °F (1-4°C).

How to Propagate

Gladioli can be propagated from seeds or cormlets.

• By seed: Gladioli species can be grown from seed. Sow in spring in a cool greenhouse but do not expect Gladiolus flowers before 2 to 3 years.
• By cormlets: these are small daughter corms that naturally form around the main corm. They can be detached when lifting plants and planted the following year, but it will take 2-3 years to produce a blooming-size corm from them.

Pest and Diseases

• Gladioli are deer and rabbit-resistant, but they are toxic to dogs, cats, and horses.
• Beware of mice, squirrels, chipmunks,  voles, and gophers: they love the gladiolus corms!
• Gladioli are fairly trouble-free. However, watch for aphids, slugs, gladioli thrips, rot, or gray mold or botrytis.