Year of the Gladiolus
Gladiolus (Gladiolas): Classic Summer-Blooming Bulbs Making a Comeback.
Gladiolus Types and Popular Varieties
How To Plant and Grow Gladiolus
10 Tips for Growing Better Gladiolus
Frequently Asked Questions
Where To Buy
Gladiolus Overview and History
Gladiolus (also spelled gladiolas, and nicknamed glads) are as American as apple pie. Generations of gardeners, from Maine to California, have tucked these summer-blooming bulbs into their gardens in spring and been delighted by the gorgeous flower spikes that appear just a few months later. Buckets of long-stemmed glads are a late-summer tradition, and they can be found at almost any county fair or farmer’s market.
In fact, gladiolus are far more exotic than you may think. Most are native to Africa and other arid countries around the Mediterranean. Plant breeders didn’t begin working with gladiolus until the late 1800s, but they have had great success. Today’s glads are far showier than those that grow in the wild and the color options are simply incredible. No wonder floral designers, flower farmers, and home gardeners are finding new and creative ways to put glads front and center.
Types of Gladiolus
Gladiolus owe their botanical name to the Latin word gladius, which means sword. It’s an accurate description of the plant’s stiffly upright form and narrow, blade-like leaves. There are several different types of glads in cultivation. They vary in height as well as in flower form and size.
Grandiflora Gladiolus Hybrids
The gladiolus that grew in our grandmother’s and great-grandmother’s gardens were probably grandifloras. They have the classic orchid-like flower shape and come in an incredible range of colors, including pink, purple, red, yellow, green, white, and orange, plus many bi-colors. Flowers are 5 to 6” across. Grandifloras grow 3 to 4-feet tall and have 12 to 20 blossoms per stem. They are reliable winter hardy in zones 7 and warmer.
Dwarf Grandiflora Gladiolus
These miniature gladioli produce 2 to 3-foot stalks and display 2-3” wide, open-faced flowers. Being smaller in size and often not needing staking, dwarf glads are a popular choice for flower gardens, containers, and cutting gardens. “Butterfly glads” are sometimes classified as dwarf hybrids and sometimes as Primulinus hybrids. They feature throat blotches in contrasting colors. “Glamini” glads also fall into this category. As with the grandiflora hybrids, these corms are reliably winter hardy in zones 7 and warmer.
Gladiolus Nanus Hybrids
These flowers resemble grandifloras but are 1/2 to 2/3 the size and there are usually just 6-7 flowers per stem. The color range is more limited, with most varieties having blossoms that are red, white, pink, or rose (plus bicolors). At just 18 to 24 inches tall, these smaller and less formal glads work well in pots and are a lively addition to a mixed flowerbed. Gladiolus nanus bloom in early to midsummer and will usually survive the winter in zones 5 and warmer.
Byzantine Gladiolus (G. communis var. byzantinus)
Byzantine glads have naturalized in many southern gardens. Each arching 2-foot stem displays about a dozen tubular, bright magenta flowers. Bloom time is early to midsummer. The corms are hardy in zone 7 and warmer.
Dalenii Gladiolus Hybrids (formerly Gladiolus primulinus)
These glads have slender, 2 to 3-foot stems with flowers that are about half the size of grandiflora types. The blossoms appear to be “hooded” rather than fully open. Dalenii hybrids are hardier than grandifloras and will survive the winter in zone 6 and warmer.
Peacock Orchids (Gladiolus callianthus)
Commonly known as peacock orchids, these gladiolus relatives are now classified as Acidanthera murielae.
Popular Gladiolus Varieties
(All are Gladiolus grandiflora unless noted).
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- Costa: Ruffled, lavender-blue flowers with darker purple edges.
- Fun Time: Ruffled flowers with a bold red rim around a bright yellow center.
- Green Star: Stunning lime green flowers.
- Lumiere: Bold jewel-like color combination of hot pink, mauve, and violet.
- Priscilla: Creamy white flowers with pale yellow centers and pink edges.
- Vulcano: Brilliant fuchsia-pink. (G. nanus)
How to Plant and Grow Gladiolus
- Gladiolus (gladiolas) should be grown in well-drained soil and full sun.
- You can grow them in a cutting garden, add them to your perennial garden, grow them in raised beds or containers, or plant the corms in your vegetable garden.
- Before planting, prepare the soil by loosening the planting area to a depth of 6 to 10”. Adding compost and an all-purpose granular fertilizer will help your glads reach their full potential.
- You can expect the flowers to begin opening 80-90 days after planting. To extend the bloom time, don’t plant all the corms at once. Plant the first batch in spring after all danger of frost has passed. Plant additional corms every week or two until early summer (about 90 days before the first fall frost).
- Plant grandiflora types 6 to 8” deep. Planting deeper helps keep the stems upright. Dwarf glads should be planted 4 to 6” deep. Space the corms 4 to 6” apart on center. Use the closer spacing if you plan to cut most of the stems before they are fully open.
- Water regularly and deeply, especially during dry spells. When plants are stressed by heat and drought, they become more susceptible to pests and disease. Applying 2 to 3” of mulch after planting will help retain moisture and control weeds.
10 Tips for Growing Better Gladiolus
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Plant Gladiolus Corms in Succession for Longer Blooms
Start planting corms in mid to late May and continue planting every 10-14 days until early July. This will keep the bouquets coming from late summer through fall.
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How to Stake Gladiolus
Glads can lean or be toppled by gusty wind or a heavy downpour. Support the stems by tying them to bamboo canes. To support a large planting, put stakes at the ends of the row and surround the stems with twine. Don’t want to bother with staking? Stick with shorter glads that grow just 2-feet tall.
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Growing Gladiolus in Containers
Gladiolus can be grown in planter boxes, tubs, and large urns. Grow them on their own, or pair them with cannas, colocascia (elephant ears), caladiums, or coleus. If you plant glads in nursery pots, you can add them to your perennial garden right before they come into bloom.
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Overwintering Gladiolus Corms in Cold Climates
In areas where gladiolus are not winter hardy (colder than zone 7 for most grandifloras), most gardeners plant fresh corms each spring. Another option is to overwinter the corms indoors. In fall, dig up the corms and cut off all but an inch or so of the stem and leaves. Let the corms dry for 1-2 weeks in a warm place with good air circulation. Then store cool and dry at about 50°F.
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Mix Gladiolus Colors and Forms
Glads come in so many beautiful colors and you may be surprised by which ones you like best. Explore the options by planting some assorted colors. Don’t miss the bi-colors and ruffles!
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Best Soil for Gladiolus
True for most garden flowers, but also your key to success with glads. Rich, well-drained soil is ideal. Poor soil can be improved by digging in plenty of compost. Avoid planting in heavy clay or in soil that gets soggy.
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How Much to Water Gladiolus
Glads are susceptible to thrips and spider mites, which can disfigure the flowers. These pests can get the upper hand when plants are stressed by heat and drought. Keep plants as strong and healthy as possible by ensuring they get at least an inch of water per week.
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Choose Large Gladiolus Corms
High-quality corms may cost more, but larger corms will give you taller stems with more flowers.
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When to Cut Gladiolus for Bouquets
For the longest vase life, harvest your glads when the bottom two flowers are fully open. The rest will gradually unfurl in the vase. Snap off spent flowers and recut the stem as needed.
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Arranging Gladiolus Cut Flowers
It can be challenging to integrate a 3-foot stem of glads into a tabletop arrangement. Don’t be afraid to trim the stem to size. Cut off some of the top or shorten the stem and remove a couple of the lower flowers.
Gladiolus FAQs
Plant gladiolus (gladiolas) corms in spring after all danger of frost has passed. For flowers all season, plant a new batch every 10 to 14 days until early July (about 90 days before your first fall frost).
Plant grandiflora gladiolus 6 to 8 inches deep. The extra depth helps keep tall stems upright. Plant dwarf glads 4 to 6 inches deep. Space corms 4 to 6 inches apart.
It depends on your climate and the type. Grandiflora and dwarf gladiolus are winter hardy in zones 7 and warmer, Dalenii hybrids in zone 6 and warmer, and Gladiolus nanus in zone 5 and warmer. In colder areas, plant new corms each spring or dig and store them over winter.
In fall, dig up the corms and cut off all but about an inch of stem and leaves. Let them dry for 1 to 2 weeks in a warm spot with good air circulation, then store them cool and dry at about 50°F.
Gladiolus flowers begin opening about 80 to 90 days after planting.
Tall gladiolus can lean or topple in wind or heavy rain. Tie stems to bamboo canes, or for a row, put stakes at each end and run twine around the stems. To skip staking, grow shorter glads that reach about 2 feet tall.
Give gladiolus at least an inch of water per week and water deeply during dry spells. Heat- and drought-stressed plants are more likely to get thrips and spider mites. A 2- to 3-inch layer of mulch helps hold moisture.
Cut gladiolus when the bottom two flowers are fully open. The rest will open in the vase. Snap off spent flowers and recut the stem as needed.
Learn more about Year of the Gladiolus…
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The National Garden Bureau recognizes and thanks Breck’s, an NGB member, as author and contributor to this fact sheet.
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