Gladioli are a gold standard in the florist trade, but they are so easy and economical to grow at home that any gardener can enjoy these showy blossoms. Avid glad fans often fill entire rows or garden beds with these colorful corms for the sole purpose of growing them for bouquets. But if the tender glads bred for cut flowers are too flamboyant for your tastes, try one of the resilient winter-hardy varieties, which are equally lovely and can remain outside year-round (see examples in our list of 18 stunning garden bulbs). Whether you wish to fill a vase with magnificent cut flowers or to keep your glads in the garden among other perennials, you’ll find a range of striking varieties in nearly every color of the rainbow.

Photo by: Shannon Marie Ferguson / Shutterstock.com.

Botanical name:

Gladiolus xhortulanus

Common names:

Common gladiolus, garden glad, and sword lily (because of the long, pointed leaves)

Zones:

Perennial in zones 8-10. Can be grown as annuals in zones 2-7. Some G. nanus types are hardy to zone 4 or 5.

How they grow:

Although you will often see glads labeled as “summer bulbs,” they are herbaceous perennials that grow from bulb-like corms covered with a fibrous papery skin. Unlike spring bulbs, glad corms are sensitive to freezing temperatures and must be dug up in fall and stored until planting time the following spring. In mild climates, some hardier glad hybrids can be left in the ground over winter.

Types:

You’ll find countless cultivars of glads in local garden centers and catalogs, all derived from various combinations of more than 250 species, most of which are native to southern and central Africa and Eurasia.

The three main glad groups are:

  • Grandiflora: The largest group of garden cultivars. These hybrids are the showiest of the bunch, with blooms up to 6 inches wide and the most extensive range of colors.
  • Nanus: Another group commonly grown in the garden. Miniature hybrids that tend to be more cold-tolerant than their taller cousins.
  • Primulinus: Have daintier hooded flowers and very narrow leaves.

Flower characteristics:

Most garden glads come in nearly any color and shade (except for true blue) in both solid and multicolored forms. Depending on the cultivar, the petals may be frilly, ruffled, semi-ruffled or plain, and the size can range from miniature (under 2 ½ inches in diameter) to gigantic (over 5 inches). The flowers are typically arranged on only one side of the stem and open in succession from the bottom up, with the largest flower at the base. As a bonus, hummingbirds really love these flowers!

Height:

1 to 5 feet

Bloom time:

From early summer until frost, depending on the cultivar and when the corms are planted.

Gladiolus corms ready for planting. Photo by: Longfield Gardens.

When to plant:

You can plant glad corms as early as a month before the average last frost date in your area. Depending on the cultivar, gladiolus take anywhere from 60 to 120 days after planting before they flower. You can stretch the blooming season by making succession plantings of corms at two-week intervals through early July and by intermixing varieties that take different lengths of time to mature. Make your last planting about 12 weeks before the first frost date.

Where to plant:

Depending on your purpose, you can plant glads in flower beds and borders, vegetable gardens, cut flower gardens, and even containers. All they need is a sunny location and one protected from the wind to avoid damage to the tall flower-laden stalks. If you are integrating glads into an established flower garden, use them to fill in spaces that need color or vertical interest. They will begin blooming in late summer when many other flowers begin to fade. In a vegetable garden, plant your glads in rows alongside the rest of your crops or use them to fill in the gaps left behind after you remove early-season edibles, such as peas, lettuce, and spinach.

Planting depth and spacing:

Gladiolus corms can vary in size, depending on the type of glad you’re planting. As with other bulbs, the larger the corm the deeper and farther apart it goes into the ground, ranging anywhere from 2 to 6 inches. For the best results, follow the recommendations given on the package. Always plant corms with the flatter side facing downward, and the narrower, pointed end facing up.

Soil:

Glads aren’t fussy and will thrive in many different soil types, but good drainage is a must. Before planting each spring, work the soil several inches deeper than the planting depth of the corm and amend it with organic matter if necessary. Loose, well-tilled soils that produce good vegetable crops are often perfect for growing gladiolus.

Staking:

Glads that grow 3 to 4 feet or taller will probably need to be staked or caged to prevent the stalks from bending and breaking. You should set the stakes in the ground at planting time to avoid damage to the corms.

Watering:

After planting, water glads thoroughly and then keep the soil evenly moist throughout the growing season. During dry weather, soak the ground thoroughly to supply the equivalent of an inch of rainfall per week. To help conserve moisture and control weeds, apply a 2- to 4-inch layer of mulch around your plants. (See How to Mulch and Avoid Mistakes.)

Pest problems:

The biggest threat to gladioli are thrips, tiny flying insects that feed on the foliage and flower buds. Because thrips are hard to spot without a magnifying glass, watch your glads for signs of thrip damage, which includes silvery streaks and small white patches on the leaves and buds that fail to open. See these tips from bulb supplier Old House Gardens for identifying and getting rid of thrips.

Winter storage:

After a glad blooms, the original corm begins to wither away and a new one forms for the next year’s growth. In areas where gladiolus aren’t hardy, you can overwinter the newly formed corms until the following spring by digging them up in fall once the foliage has been killed by frost. Here are the basic steps:

  • Cut the stalk off just above each corm, brush or wash off the soil, and then allow the corms to dry in a well-ventilated area for a couple weeks.
  • Separate the new corms from the old one, and store them in a dark, dry, cool area. Ideal storage temperatures are just above freezing (between 35° and 45° F). A good method of storage is to layer them in a cardboard box with newspaper in between, a paper bag would also work.
  • Some corms also produce cormels -- smaller plantlets that can be separated from the parent and grown into new plants. However, cormels often won’t produce blooms for several years until they grow larger and are best discarded unless you have the patience to save them and replant them each spring.
  • If you have a variety of glads, label the corms by color or cultivar before storing them so you know what you’re planting the following spring.
  • Check your corms periodically to make sure they are in good condition. If they have started to sprout new growth, move them to a cooler spot. If you notice signs of rot, the packing material may be too moist.
  • If you don't want to fuss with digging up and storing the corms each year, simply treat them as annuals and buy new ones every spring. The most common glad cultivars are inexpensive and widely available, so it’s often more cost effective to replace them, especially if you factor in the time you’ll save.

DISPLAYING GLADS

  • Generally, glads are long-lasting cut flowers and will remain attractive for at least a week in a vase, but for the greatest longevity cut the stems when only a few flowers are open at the bottom the spike. The rest of the florets will open gradually over the next few days. As they do, pull off the bottom florets when they fade.
  • Cut your glads in the early morning or late evening, when the temperatures are coolest and the stems are well hydrated. If you plan to store and replant your corms, don’t be tempted to cut off all the foliage along with the flowers. Leave as many leaves as possible on the plant to help nourish the corm for the following spring.
  • Although glads look stunning arranged in a tall vase, you can cut the blooms from the stems and arrange them in a shallow vase or bowl to make an attractive, low-profile centerpiece for a dining room table. Here are more tips for creating sophisticated floral tablescapes and centerpieces: Flower Arranging 101.

8 GORGEOUS GLADIOLUS FLOWERS

Swipe to view slides

Photo by: grjo02022 © Visions BV, Netherlands / Johan Groot.

Gladiolus ‘Black Beauty’

Why we love it: Nearly black blooms with deep burgundy highlights are as plush as velvet. Especially dramatic when paired in the garden or a vase with a pure white glad, such as ‘White Prosperity.’

Height: 4 to 5 feet

Days until bloom: 70 to 100

Also try: ‘Espresso’ and ‘Black Jack’, which also have luxuriant burgundy-red flowers.

Photo by: Longfield Gardens.

Gladiolus ‘Green Star’

Why we love it: In the mixed flower garden and in floral arrangements, this striking glad with ruffled blooms the color of lime sherbet is a refreshing complement to fuchsia, dark purple, orange, and other bold flower colors.

Height: 3 to 4 feet

Days until bloom: 70 to 75

Also try: ‘Kiev,’ a showy chartreuse-green glad with pink highlights and impressive 4-inch-diameter blooms.

Photo by: visi04474 © Visions BV, Netherlands / VisionsPictures & Photography.

Gladiolus ‘Peter Pears’

Why we love it: Velvety blooms the color of peach sorbet open to reveal bright strawberry-red centers. Its tall upright spikes and strappy foliage also add a strong vertical element to the garden.

Height: 4 to 5 feet

Days until bloom: 60 to 100

Also try: ‘Boone’, a hardy zone 5 glad with apricot flowers and yellow throats marked with red.

Photo by: Shannon Marie Ferguson / Shutterstock.com.

Gladiolus ‘Priscilla’

Why we love it: Lovely, ladylike, and utterly enchanting, with frilly white flowers and light yellow centers, all fringed in hot pink.

Height: 4 to 5 feet

Days until bloom: 70 to 75

Also try: ‘Charming Beauty’, a miniature glad with bubble-gum pink florets and bright pink accents.

Photo by: Roger Cope / Alamy Stock Photo.

Gladiolus ‘Princess Margaret Rose’

Why we love it: Towering spikes of yellow-orange blooms edged in red heat up the summer garden with all the tropical colors of a Tequila Sunrise.

Height: 4 to 5 feet

Days until bloom: 60 to 100

Also try: 'Jester', with ruffled apricot-yellow petals and bright orange-red throats.

Photo by: Del Boy / Shutterstock.com.

Gladiolus nanus ‘Prins Claus’

Why we love it: This hardy miniature glad puts on a dramatic display year after year, first showing off its pure white petals then opening to reveal bright splotches of fuchsia. As a bonus, the corms of this zone 4 perennial can overwinter in the ground.

Height: 24 to 30 inches

Bloom time: May through July

Also try: 'Elvira’, another cold-hardy glad with pale salmon-pink blooms accented by smudges of deep pink.

Photo by: JRJfin / Shutterstock.com.

Gladiolus ‘White Prosperity’

Why we love it: Pristine snow-white flowers and ruffled petals up to 4 inches across make this glad one of the most versatile in the garden or vase. Each statuesque spike bears 18 to 20 flowers.

Height: 4 to 5 feet

Days until bloom: 70 to 75

Also try: ‘Albus’, a diminutive pure-white nanus glad under 2 feet tall.

Photo by: visi08411 © Visions BV, Netherlands / VisionsPictures & Photography.

Gladiolus ‘Wine and Roses’

Why we love it: Even more romantic than red roses, a poetic composition of soft, ruffled pink blooms embellished with wine-red hearts framed by a halo of white. Also matures early, revealing its loveliness just a couple of months after planting.

Height: 4 to 5 feet

Days until bloom: 65 to 70

Also try: ‘Mon Amour’, another dreamy tricolored glad in softer tones of pink, pale yellow, and ivory.

BUYING TIPS

  • You can purchase glad corms individually, but it’s often more convenient to buy a color-coordinated mix that will look harmonious in a vase or the garden with little effort. Many bulb suppliers offer an array of popular color schemes, such as pastels, bright summer blends, rainbow mixes, and more.
  • If you’re looking for rare or heirloom gladioli, the North American Gladiolus Council offers a list of North American and European suppliers that carry hard-to-find varieties as well as recent introductions.
  • When buying glads, look for corms that are at least an inch in diameter. Larger corms produce larger blooms and those smaller than 3/4 inch may not flower the first year. Also choose corms that are relatively tall and plump rather than wide and flat. Thicker corms often produce more robust flowers.

Online resources include:

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