How to Grow Gladiolus to Enjoy in Your Garden or Use for Arrangements

Gladiolus, also known as sword lily, is a genus of perennial flowering plants in the iris family. The plant is recognized by its bright, funnel-shaped blooms that grow on upright stalks, adding color and vertical height to the landscape. The fragrant flowers are often grown in cutting gardens, as they are an attractive addition to arrangements. What's more, gladiolus is adaptable to various growing conditions, thriving in most soils except heavy clay. Want to grow these beauties in your garden? Below, our experts share helpful advice on planting and caring for gladioli.

When to Plant Gladiolus

Plant gladiolus in spring after the threat of frost has passed, which may vary depending on the zone you live in. No matter your climate, the most important thing to keep in mind when planting gladiolus is to make sure it's protected from below-freezing temperatures, says gardening author Kathy Jentz.

How to Plant Gladiolus

Gladioli are typically grown from corms. Here's how our experts say to plant them for optimal success.

1. Select the best corms: Look for healthy corms that aren't damaged and aren't too small.
2. Prepare holes: Dig a small hole for each corm, making each hole about 4 to 6 inches deep. (The exact depth varies depending on the size of the corm.) Space the holes about 6 inches apart in an arrangement of your choosing.
3. Orient them properly: Plant the corms like onions, with the pointy end facing up at the sky, and the roots down.
4. Backfill and water well: It's important to water (but don't overwater) newly planted gladiolus corms while they establish themselves. 

How to Care for Gladiolus

Get your newly planted gladiolus corms off to the best start by providing their ideal growing conditions.

Sun

Gladiolus needs full sun for the upright growth the plant is known for. "When the corm is placed in full sun, the stem of the plant is encouraged to grow straight up for a colorful, architectural effect in the garden," says gardening author Teri Speight.

Soil

Gladiolus plants prefer well-drained soil that is a bit loamy or sandy and not overly fertile, says Speight. Don't overwater the soil or the corms can rot.

Water

Regular watering is important when the corms are first planted, but you can scale it back once the plants are established. "A weekly watering will suffice," says Speight. "However, as our climate changes, additional watering during times of drought will help the plant perform better."

Temperature

Gladiolus likes warm weather and thrives in temperatures of at least 50 to 75 degrees Fahrenheit. These plants are somewhat drought-tolerant and can handle dry conditions. 

Fertilizer

As long as your soil is adequate, gladiolus won't require fertilizer. "Too much fertilizing will produce more foliage and fewer blooms," says Speight. Do a soil test before planting to see if your soil needs amendments. 

How to Prune Gladiolus

Gladiolus doesn't grow woody stems like a shrub, so no pruning is needed for shaping or structure. Your "pruning" will mostly be focused on late-season cleanup. "After blooming, remove the faded flowers and then cut the whole stalk down," says Jentz.

How to Propagate Gladiolus

There are two ways to propagate gladiolus: from seeds or corms.

From Seeds:

You can propagate gladiolus from seeds, but this typically isn't done because you won't see flowers for a few years. If you're up for the challenge, here's how.

1. Start indoors: In late winter, fill seed trays with moist seed starting mix. Sow one seed per cell and cover lightly with soil.
2. Keep them watered well: Don't let the seed trays dry out. Sprouts should appear in about a month.
3. Wait for warmth: Transplant the seedlings outdoors once the temperature is consistently 60 degrees Fahrenheit or higher.
4. Protect the new corms: It could take three years to get flowers with this method. While you wait, you will need to protect the new plants from cold winter weather (unless you're in zone 8 or warmer). This means digging up, drying, storing, and replanting the new corms annually. 

From Corms:

It's faster and more common to grow new gladiolus plants from an existing corm rather than from seed.

1. Dig up a corm in the fall: As the growing season winds down and the foliage has faded, dig up a corm to use for propagation.
2. Clean and dry: Brush all the soil away and wait until the corm has dried. Cut away the stem.
3. Remove the cormlets" Each corm will have smaller "cormlets," loosely attached. Carefully remove the cormlets to use for the propagation of new plants.
4. Dry and store: Once your cormlets are dry, store them in a cool, dry place over the winter.
5. Plant your cormlets in the spring: Plant your cormlets the same way you would full-size corms. They likely won't bloom the first year, but they'll bloom faster than plants grown from seed.

Overwintering Gladiolus

If you live in zone 8 or warmer, overwintering gladioli couldn't be easier. Leave the corms in the ground, and insulate the soil with straw or mulch to help protect from chilly temperatures. 

In zones 7 and colder, more work is required for overwintering. In these cases, gently dig up the corms, trim away the excess plant material, and carefully clean the corms. Then dry the corms for a week or two and store them in a cool, dry location like an unheated shed or garage over winter to prevent the corms from freezing.

Tips for Growing Gladiolus Flowers in Containers

Gladiolus can flourish in pots and containers. "Make sure the pots allow for the corms to be planted 4 to 6 inches deep and at least 2 to 4 inches apart," says Speight. Planting the corms close together allows the tall stems to lean on each other for support. "Place the corm on its side in well-draining potting soil so water will not pool at the shallow indentation," says Speight. She advises placing the container in full sun for the best results.

Common Problems 

Gladiolus is relatively easy to grow, but it's still possible to encounter some common issues. Educating yourself is a good way to avoid simple problems.

• Not enough sun: Carefully choose your planting location. "Gladiolus requires full sun for best blooming," says Jentz. 
• Lack of support: Like many other large-blooming flowers such as peonies, gladiolus benefits from support. This plant may need some staking if it is not supported by surrounding plants," says Jentz.
• Selecting non-hardy varieties: Grow hardy gladiolus varieties in cold regions. "Hardy varieties will behave as a perennial in your garden," says Jentz. "Be sure to plant the bulb deep enough and give it some mulch for extra winter protection, especially if you are in USDA zone 6 or lower."