Gladiolus: How to Plant, Grow and Care for Gladiolus Flowers

Gladiolus (plural gladioli), with their dramatic sword-like leaves, have sturdy flowering stems that stand up to 5 feet tall and have been loved by generations of gardeners!

These trumpet-shaped flowers are also known as sword lilies and 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. This tender perennial is 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.

Botanical Name: Gladiolus palustris

Common Name: Gladioulus

Family: Iridaceae

Plant Type: Corm, or bulbotumer

Hardiness Zones: 7 – 10 (USDA)

Sun Exposure: Full sun

Soil Type: Sandy loam

Soil pH: 6.0 – 6.5

Maturity: 70 – 95 days from corm to flower

Height: 2 to 5 feet

Spacing: 4 to 6 inches apart in all directions

Bloom Time: Summer through frost

Flower Color: Pink, red, orange, yellow, purple, green, and white

Native Area: Mediterranean region, Africa, and Europe

Quick Guide: Planting, Growing & Caring for Gladiolus

• Gladiolus come in a rainbow of colors
• Start plants from corms, not seeds
• Plant in spring in well-nourished soil and full sun
• Water regularly, protect from wind, and add support if needed
• Expect blooms about 3 months after planting corms

Gladiolus Plant Care

Gladiolus are one of the most popular cut flowers in the world and one of the simplest and easiest to grow. Plant the corms in the spring for flowers in late summer.

You can choose from a rainbow of gorgeous colors that will make your summer flower arrangements more interesting.

They’re simple to grow and adaptable, but they thrive in fertile, well-drained soil with consistent moisture. Commonly known as gladiolus, gladiola, gladiolas, glad, and the plural gladioli, these plants have vertical, sword-shaped leaves and a fanning growth habit. This is how they got their name, gladius, which is Latin for “sword lily.”

These lovely flowering plants are members of the iris family (Iridaceae) and come in a variety of colors and sizes/
Gladioli typically grow between 2 and 5 feet tall, and their flowers come in a variety of sizes, from ‘miniature’ blooms that are less than 3 inches across to ‘giant’ blooms that are more than 5 inches across. In order to create a beautiful contrast with shorter plants, it is common practice to position taller varieties, which require staking, in the back of a garden.

They are winter hardy in USDA Hardiness Zones 7 and above, so their corms can be left in the ground year-around. Most gladioli corms in Zones 6 and lower should be dug up and stored for the winter before being replanted in the following spring.

Light

Gladiolus flowers do best in full sun, but they will still bloom in partial shade.

Soil

Gladiolus bulbs can be grown in any well-draining soil. Even though glads can tolerate shallow planting, placing them at least 6 inches below the surface of the soil will provide support for their emerging shoots.

Water

After planting, thoroughly water glads and then maintain an even soil moisture level throughout the growing season. When it’s dry, soak the ground well enough to give it the same amount of water as an inch of rain per week.

Applying a 2- to 4-inch layer of mulch around your plants will help retain moisture and control weeds.

Temperature and Humidity

If you plant your glads too soon, you won’t get any flowers sooner. In cold soil, gladioli wilt and may even rot.

Gladiolus bulbs should be planted in the ground when the temperature drops to at least 60 degrees Fahrenheit at night and in a location that will get at least five hours of direct sunlight per day.

July through frost is the blooming period for gladioli. Planting new corms every two weeks will extend the blooming season because the plants do not bloom continuously.

The foliage will be killed by a light frost, but the plant will still survive. Be sure to dig up the gladiolus corms before a hard freeze (28 degrees Fahrenheit), or the plants may die. Using a spade, carefully remove the entire plant from the soil while grasping its crown.

Avoid damaging or bruising corms when digging. Shake off any loose soil, but do not wash the corms, and discard any that are damaged. Reduce the height of the stalk to 1-2 inches above the corm. If desired, save the small cormels separately.

Fertilizer

Use a balanced, 10-10-10 liquid fertilizer to fertilize newly emerged gladioli shoots.

How to Plant and Grow Gladiolus

Site Preparation

Gladiolas require full sun and regular water during growth and bloom. They should be planted in well-drained soil that is 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 our video 6 Tips for Growing Great Flowers). This helps condition the soil, which improves drainage and will also increase the ability of lighter soils to hold water and nutrients.

If possible, provide protection from the wind. The best time to plant gladiolus corms is in the spring through early summer. After approximately 90 days, the flowers bloom.

Plant gladiolus corms in the spring after the danger of frost has passed and the soil temperature has reached at least 55 degrees Fahrenheit (13 degrees Celsius).

How to Plant Gladiolus

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.

When planting the corms, make sure to thoroughly water them. When planting tall varieties, be sure to support them with stakes. Take care when using the stakes so as not to harm the corms.

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.

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 lower, 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.

Tip: An easy way to reclaim corms at the end of the season is to plant them in a small container like a strawberry basket. When fall arrives, just dig the entire container and bring inside.

Common Pests and Plant Diseases for Gladiolus

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.

Watch closely for aphids, spider mites and thrips on leaves, stems or flowers. If found, take the following common sense, least-toxic approach to pest control:

• 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 (use soaker hoses or drip irrigation)
• 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.