Gladioli flowers look marvellous, planted at the back of large borders, foundations, and the garden bed. They are beautifully planted around vegetable gardens to help attract pollinators and hummingbirds. And to top it off they make lovely cut flowers. We’ve got the complete guide on how to plant gladiolus bulbs including all the care information you need to keep them coming back.
Growing Gladiolus From Bulbs
Gladiolus plants are showy summer blooms with upright sword-like foliage. Unfortunately, the plants are only hardy to the south, so they are usually planted outdoors in spring, lifted from the ground, and overwintered indoors.
Gladiolus are grown from corms – similar to tulip bulbs. The terms bulb, corm, and tuber are often lumped together as a single term ” bulbs”.
Blossoms: The flowers are funnel-shaped with six showy petals. Blooms range in size from 2-5 inches. Petals may be ruffled or smooth and come in a wide range of colors.
Colors: Glads are white, cream, light yellow, ivory, light orange, orange, salmon, scarlet, red, deep red, black-red, rose, violet, lilac, lavender, and purple. Every color looks stunning against the dark green leaves of the plant.
Height & Spread – Common garden gladiolus (G. x hortulanus) grows to a height of 2-4 feet, and evening gladiolus (Gladiolus tristis) will grow to a height of 20-24 inches. Both plants have a spread of 6-8 inches.
Growing Season: Begin planting in mid-spring after the last frost in your area. Continue to plant every two weeks until the middle of July. Corms will bloom from 70-100 days from planting. Gladioli bloom from early summer until frost. However, the plants don’t bloom continuously, so planting new corms every two weeks will extend the blooming season. This will also help keep blooming flowers available for the bees, who love gladioli.
Learn More: Check out these guides on bulb planting:
- Bulbs for Spring Planting and Beautiful Summer Blooms
- Fall Bulbs to Plant for Beautiful Spring Blooms
How toPlant Gladiolus Bulbs In The Garden
Gladiolus are native to South Africa and grow best in a warm climate with sandy loam soil with good water drainage. Any soil that is good for growing vegetables is good for gladiolus. Mix compost into planting beds in spring to help water drainage and fertility. Gladiolus don’t compete well with other plants or weeds, so keep the area around them open for best results.
Hardiness: Gladiolus are tender bulbs. Common glads are hardy to warm climates in USDA hardiness zones 9-10, whereas evening flower gladiolus is hardy to USDA zones 7.
The smaller growing hardy gladiolus are cold hardy to USDA zone 5.
Planting Out: Gladiolus can be planted about two weeks before the last expected spring frost. It will take 70 to 90 days from planting until flowering.
Plant 2 to 6 inches deep, depending on the size of the corm, and cover with 2 inches of soil. Space corms 5 inches apart in rows or groups of 10 to 15 corms. Once the plants are about 6 inches high, it’s an excellent idea to hill up the soil around the base of the plant to help support the stem.
Bloom Time: For a continual harvest of flower spikes, plant a few corms every couple of weeks until early summer for blooms that last until the first frost. The plants don’t bloom continuously, so producing new corms every two weeks until early July will extend the blooming season.
Planting Lots of Bulbs?
Care for Gladlous flowers
Sun Requirements: Gladlous require full sun. They will tolerate partial shade in the morning, but they flower more profusely in full sun.
Soil Requirements: Plant in soil that plenty of organic matter with good drainage and slightly acidic with a pH of 6.5-7)
Water Requirements: Glads like plenty of water. Ideally, the plants should get at least 1 inch of rain or manual watering a week. Avoid spraying water on the leaves and flowers to prevent them from tipping over. You will want to keep an even soil moisture level to produce large flowers.
Fertilizer Requirements: Apply a water-soluble fertilizer 4 to 6 inches away from the stems when the plants are 6 to 10 inches tall. Apply a second application when the flower spikes start to show color. Keep the plants weed-free and mulched with a 2- to 4-inch-thick layer of bark mulch, wood shavings, or straw.
Staking requirements: Taller varieties will probably need staking to prevent the flower spikes from flopping over in the wind. Hilling the soil will help, but staking individual flower spikes or creating a grid with stakes and string are the best ways to keep flower stalks upright. Single stem supports are ideal.
Pests & Diseases of Gladiolus
Gladiola is generally carefree plants but they can get infested with a few pests and are susceptible to a few diseases.
Pests: Gladiolus can be attacked by aphids, bulb mites, thrips, and spider mites.
Aphid infestations will present with curled or stunted leaves. Leaves may turn brown, and flowers may be distorted. Treat with insecticidal soap or a simple blast of forceful water from the hose. Be sure to clean the underside of the leaves.
Flowers that fail to bloom or produce yellowed or distorted foliage may be infected with bulb mites. If you suspect these pests, you will need to dig the gladiolus bulbs out of the ground to look for them. The mites are white, about 1/25 of an inch long. Dig and destroy all corms infected and the soil in which they were growing. Do not compost.
Diseases: The corms of the gladiolus are suspectable to fungal disease and mosaic virus. With good environmental practices in your garden, you can prevent those diseases from taking hold.
Don’t leave debris hanging around the garden; keep it clean. Don’t plant soft or cut corms; discard them. Do not overwater – overwatering will cause the corms to rot and invite insects which will cause diseases to spread.
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Storing Gladioli Corms
In USDA zones 7 and 8, mulch gladiolus beds with a layer of hay or straw to protect through the winter.
If glads are not hardy in your zone, you can still save them for the following spring.
About 5-6 weeks after they bloom, gently dig the corm out of the ground with a spading fork when the leaves turn yellow.
Clean off gladiolus corms, cut the stalk within half an inch of the corm, and let them cure for one to two weeks in a warm, airy location. Discard the old shrivelled corms.
Once dried, remove the old corm and any small cormels (save the cormels for propagating). Store the large, new corms in a paper bag or plastic mesh bags (the best way, in my opinion) and store them in a well-ventilated room where temperatures remain from 35 to 50 degrees F.
Plant gladioli corms the following year for another spectacular show!
If you’re patient, you can save the small corms for planting the following spring. These flowers will take 1- 2 years to bloom, but it is an excellent way to multiply and replenish your stock next year.
Gladiolus for the Cut Flower garden
Cut your gladiolus flower stalk early in the morning. Use a clean, sharp knife and harvest when only the lowest bud is open on the spike. Leave at least five leaves on the stem to encourage continued blooming.
Place flowers into a vase of warm water overnight. In the morning, arrange the gladiolus in a vase filled with fresh water and flower preservative to prolong their bloom.
Plant Your Gladioli bulbs again and again
Flowers like glads, tulips, and dahlias are excellent additions to the spring and summer gardens because you can replant them again and again.
If you’re planning a summer garden this year and thinking about planting some gladiolus, I highly recommend staggering the plantings every two weeks until early summer. You will love the magical color dance the flowers perform all summer long when planted this way. Trust me!
I hope you have an enjoyable and wonderful gardening season.
Gladioli are hardy to zones USDA zones 7-9 and will come back year after year without intervention. If you are in a colder zone, you can overwinter the gladioli corms and replant them the following spring.
Plant gladiolus at the back foundation plants and borders or around garden edges. Anywhere you need a pop of tall color, gladioli will be a good addition. Be sure to plant the corms in full sun with well-drained soil.
Gladioli do not multiply like dahlias. Instead, the gladioli corms will grow tiny cormlets that you can plant in the spring; The cormlets will take 1-2 years to bloom.
Technically, yes. While you have to dig up the bulbs and store them over winter, the plant will grow and bloom after re-planting.