Gladiolus is a classic perennial known for its tall flower spikes and large, colorful blooms. Great cutting flowers, gladioli look spectacular in summer bouquets. Here’s how to grow gladioli in your garden.
Commonly called “glads,” these lovely flowering plants are available in a multitude of colors and typically reach between 2 and 5 feet in height. Their blooms also range in size—from “miniature” flowers less than 3 inches in diameter, to “giant” flowers greater than 5 inches across!
The taller varieties, which need to be staked, are often placed in the back of a garden to nicely complement shorter plants.
Note: In Zone 7 and colder, gladioli corms will likely need to be dug up in the fall, stored, and replanted the following spring. Find your planting zone here and see instructions for this process below.
PLANTING
WHEN TO PLANT GLADIOLUS
Start planting gladiolus corms in the spring, once the danger of frost has passed and the soil has warmed to at least 55°F (13°C). See your local frost dates here.
From your last frost date to early summer, plant another round of corms every 10 days or so. This will result in continuous blooms through early fall!
Depending on the variety, it takes between 60 and 90 days from the time glads are planted for the corms to root, grow, and bloom.
CHOOSING AND PREPARING A PLANTING SITE
For the best flowers, plant glads in full sun.
Gladioli like well-drained soil that’s moderately fertile. They will not do well in heavy, soggy soil.
Ready your garden by using a garden fork or tiller to loosen the soil to about 12 to 15 inches deep. After loosening the soil, mix in a 2- to 4-inch layer of compost or aged manure.
HOW TO PLANT GLADIOLUS
To ensure large-sized blooms, plant corms that are 1¼ inch or larger in diameter.
Set the corm in the hole about 4 inches deep with the pointed end facing up. Cover with soil and press firmly.
Space the corms 6 to 8 inches apart.
If you grow gladioli primarily for cut flowers, plant them in rows. It’s easier to tend the plants and to harvest the flowers.
If planted with other flowers in borders or annual beds, plant the corms in groups of 7 or more for the best effect.
Water the corms thoroughly at planting.
If you’re planting tall varieties, be sure to stake them at planting time. Be careful not to damage the corms with the stakes.
CARE
HOW TO GROW GLADIOLUS
Put a 2- to 4-inch layer of mulch around your gladioli to keep your soil moist and help prevent weeds.
If you get less than 1 inch of rain a week, water your plants regularly throughout the summer. Otherwise, water them moderately when in growth to keep the soil moist.
Remove the faded/dead flowers to ensure continuous blooms. Once all the flowers on a stalk are gone, cut the stalk off at about 2 to 3 inches above the soil.
Be sure to leave the plant intact so it can mature and grow the corms for the next season.
Winter Protection for Gladiolus
If you live in USDA Hardiness Zone 8, put down a layer of hay or straw for winter protection. In warmer regions, gladiolus can remain in the ground through winter, provided a hard freeze (28°F or colder) isn’t common in your area.
In colder regions (Zone 7 or colder), dig up gladioli corms once the foliage has faded after the first fall frost. A light frost will kill the foliage, but not the rest of plant. Be sure to dig up the gladiolus corms before a hard freeze, or the plants could be fatally damaged.
See corm storage tips below.
PESTS/DISEASES
Gladiolus corm rot (Fusarium wilt)
Gray mold
Viruses
Aster yellows
Spider mites
Thrips
Aphids
HARVEST/STORAGE
CUTTING GLADIOLUS FLOWERS FOR BOUQUETS
Cut the flower stalks early in the morning or at night, not during the heat of day.
Use a sharp knife and bring a bucket of lukewarm water to the flower bed.
Cut stalks with only one or two open flowers. The rest of the buds will open after you put them in a vase.
Cut diagonally through the stalks and place them in the bucket.
Leave at least four leaves on the plant in the ground if you want to re-use the corms.
Place the bucket with the flowers in a cool dark place for a few hours before arranging them in a vase.
Remove lower fading flowers and cut about 1 inch off the bottom of each flower stalk every few days.
DIGGING UP AND STORING GLADIOLI CORMS
In colder regions (Zone 7 or colder), dig up gladioli corms once the foliage has faded after the first fall frost. A light frost will kill the foliage, but not the rest of plant. Be sure to dig up the gladiolus corms before a hard freeze (28°F), or the plants could be fatally damaged.
Use a spade and dig up the entire plant, grasping the top to pull it out of the soil. Avoid bruising or injuring corms while digging. Shake off all loose soil (do not wash them off) and discard damaged corms. Cut the stalk down to 1-2 inches above the corm. Save the small cormels separately if you so desire. These will bloom in 2 to 3 years if you replant them each spring.
Allow the corms to dry in the sun for 1 or 2 days if the weather agrees. Sift out excess soil and place corms in wooden flats or trays. Cure in a warm and airy location for 2 weeks at a temperature of 80 to 85°F (27 to 29°C). Remove and throw away the oldest bottom corms (from the base of the new one).
Don’t remove the husks on the corms.
Dust the corms with a fungicide (“bulb dust”) to avoid disease problems. Place dust and bulbs in a paper bag and shake vigorously.
Store the corms in paper or cloth bags, pantyhose, or old onion sacks. Stack or hang the containers so air can move among them. Store the corms at 35 to 45°F (2 to 7°C) in low humidity. A cool basement is quite suitable. Do not allow corms to freeze.
Replant these corms in the spring for another year of beautiful blooms.
RECOMMENDED VARIETIES
‘Candyman’, for its beautiful deep pink flowers
‘Dream’s End’, which makes a good back border plant because its flower spike is up to 3 feet tall (and it has pretty light orange flowers with large yellow centers)
‘Prins Claus’, which has white flowers with splashes of pink on its petals
‘Black Star’, which has deep purple-red blooms and reaches 36 to 60 inches tall
Glamini Glads are pest resistant and bloom in full sun or partial shade. Their shorter height is perfect for the middle or front of flower beds.
WIT & WISDOM
Gladiolus is one of the August birth flowers.
Gladioli are sometimes called “sword lilies” due to their blade-like leaves. In fact, “gladiolus” itself comes from Latin gladius, meaning “sword.”
In the language of flowers, gladiolus signifies remembrance.