Planting, Growing, and Caring for Gladiolus
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Planting
For the best blooms, plant glads in full sun (6 to 8 hours of sunlight per day) in well-drained soil that’s moderately fertile. They will not do well in heavy, soggy soil. Mix compost (humus) into your soil to improve consistency and fertility.
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 ten 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.
How to Plant Gladiolus
- 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.
- 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.
Growing
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 they are growing 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 or warmer, put down a layer of hay or straw for winter protection. 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 the plant. Be sure to dig up the gladiolus corms before a hard freeze (28°F), or the plants could be fatally damaged.
- All that said, many gardeners who live in the “border” zones 6 and 7 have tried leaving them glads in the ground and found that they survived; this is a judgment call based on your microclimate, your variety of gladiolus, and climate shifts.
Digging Up and Storing Gladioli Corms
To dig up the gladioli corms for winter storage, follow these tips:
- 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 to 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 2-3 weeks. Remove and throw away the oldest bottom corms (from the base of the new ones).
- 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.
Learn more tips for storing gladiolus through the winter.
Gladioli come in a variety of sizes and colors, with the most popular being part of the following hybrid groups:
- Grandiflora Hybrids: These are the classic gladioli that produce a plentiful amount of large (5- to 6-inch) blooms in a range of colors. The plants produce flower stalks that reach up to 4 feet in height and are winter hardy to Zone 7.
- Dwarf Grandiflora Hybrids: These miniature glads are an excellent choice for containers and cutting gardens, as their flowers are about half the size of Grandifloras, and their shorter stalks don’t typically require staking. They are also winter hardy to Zone 7. Glamini gladioli are included in this group; they are pest-resistant and will bloom in full sun or partial shade.
- Nanus Hybrids: Hardy to Zone 5, these smaller gladioli look a lot like Grandifloras, but do not produce as many flowers. They tend to grow no larger than about 2 feet in height, which makes them perfect for containers or small spaces.
Some specific gladiolus varieties of note include:
- ‘Black Star,’ which has deep purple-red blooms
- ‘Candyman,’ for its beautiful, deep pink flowers
- ‘Costa,’ which sports ruffled flowers in blue-purple
- ‘Dream’s End,’ which makes a good background plant because its flower spike is up to 3 feet tall (and it has pretty light orange flowers with large yellow centers)
- ‘Fun Time,’ which has yellow flowers edged with red
- ‘Green Time,’ for its unusual lime-green flowers
- ‘Prins Claus,’ which has white flowers with splashes of pink on its petals
- ‘Priscilla,’ which produces off-white flowers with a yellow center and a pink edge
Harvesting
To cut glads for bouquets, follow these tips:
- Cut the flower stalks early in the morning or at night, not during the heat of the day.
- Use a sharp knife and bring a bucket of lukewarm water to the flower bed; cut diagonally through the stalks and place in the bucket.
- Cut stalks with only one or two open flowers. The rest of the buds will open after you put them in a vase. Leave at least four leaves on the plant in the ground if you want to reuse 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.
Catherine Boeckmann
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We are moving in a and I would like to take my gladiolus with me, what is the best way to go about potting the plant?
Hi Jessica,
Gladiolus are such beautiful flowers so we can see why you would like to take them with you. In a perfect world, you want to let your gladiolus flower completely and then allow the foliage to die back naturally in the fall before moving bulbs or removing from the soil for storage in colder areas. The corms collect energy for next year’s growing season through the foliage and it is essential to continue the growing cycle and for the flowers to return the following year.
If you must remove them before the cycle has completed, it is hard to say if you removed the corms/foliage and flowers during the growing season and placed them in pots if they would survive the move. It would unfortunately not be known until next year’s growing season. If you must move them, you should make sure to dig up the entire corm and plant in a large container with a good potting mix. They are top heavy flowers so the container will need to heavy enough to hold them.
If the flowers do not return, you will need to buy new corms to replace them in your new location.
Good luck. Hope this helps!
Someone told me to soak the corms in a lye solution before planting, ever hear of this?
On 4/29/23, I planted gladiolus corms in an area where I thought they would get 6 to 8 hours of sun a day. As it turns out, once the sun is at its highest in the sky in the summer, the edge of the porch roof puts them in the shade. They grew plenty of leaves, but never any buds or flowers. This year, I noticed that two have already started growing and are about 4 inches tall. I'm hoping that maybe they were just confused last year because of the cool spring, and I'm hoping for bloom this year. Wish them luck! If they do the same thing this year, I will dig them up this fall and find another place for them in the spring.
Update: One plant has a flower spike, but it seems soft and is drooping. I just staked it and I'm hoping for the best. We have had weather in the 90s over the last week or so, so now I am a bit grateful for that shade they are receiving.
This has me confused—
“Cure in a warm and airy location for 2 weeks at a temperature of 80 to 85°F (27 to 29°C).”
If I’m lifting the bulbs in the Fall temperatures are not 80 to 85°…….outside or inside.
Paula, Thank you for pointing this out. We’ve amended the information!
—The Editors
So, i just bought corms from a local nursery. I have no idea what variety other than the colour. I am planting them where they will get 4 to 6 hours of sun in the summer and 6 to 8 hours in the winter. I live in the tropics, so shall i expect the plants to die back in winter like the canna lilies, and ornamental turmeric and gingers? Do i need to dig them up or can i leave them in the ground year after year until they need thinning, as i do with the lilies and gingers? Thank you for your help!
It states that in USDA Hardiness Zone 8, put down a layer of hay or straw for winter protection. I feel compelled to caution against using hay. I have made the mistake of using hay, which is dried grass, as it may contains grass seeds. I am still pulling out grass sprouts! Straw is the better option.
Pls help. Planted store bought bulbs on Easter 2022. It's now May/28/22 and it looks like we planted grass. We have 12 smallest is about 18inches tall, biggest 24in. But it just looks like extra tall blades of grass. The instructions on the packet said plant them in groups, so we have 4 in each 6in diameter pot. After reading the article, I know I need replant. Will they flower soon? I don't even see any little buds. Any suggestions will be greatly appreciated
