Growing Glads

The middle of April until the beginning of July is a perfect time to try your hand at growing gladioli. Planted gladiolus corms (incorrectly called “bulbs” by many gardeners) mature quickly—expect colorful flower spikes in about two months. And making successive plantings every two or three weeks can result in bright, beautiful blooms all summer long and into the early fall.

Before you jump into the car and tear out of the driveway to search for bunches of these bulbs–er, corms, remember one important rule: You get what you pay for. If you purchase bargain gladioli, don’t expect spectacular results from them. Tall, healthy blooms are best produced from quality corms, so spend a little more to get a lot more. Normally, prime corms are at least 1-1/2 inches in diameter.

Gladiolus - by L.A. Jackson

To plant gladioli, first select an area that is in full sunlight, drains well, and is somewhat acidic. Amend the planting site with plenty of compost. Adding a time-release, bulb-boost type fertilizer will also put extra zip in the flower show.

Plant the base of the corms 4 to 6 inches deep and about 6 inches apart. Moisture is very important to developing plants—they should receive an inch of water a week. If the rains don’t come, keep the hose handy. In addition, a 2 to 3-inch layer of mulch will not only help conserve moisture, but it will discourage nutrient-robbing weeds from trying to take over.

Tall gladiolus varieties have one problem in that they can get, well, tall and easily flop over. If your planting site is exposed to prevailing winds, consider suspending a piece of common chicken wire horizontally 12 to 18 inches over the glad bed. This will allow the plants to grow up and through the holes for support.

Thrips are the main insect menace of glads. These tiny pests like to congregate in masses, and their unwanted eating habits can cause malformed and spotted flowers. A conventional insecticide such as Sevin will put the lights out on their party, but if you are looking for a more garden-friendly bug-bopper, give insecticidal soap a try.

And don’t worry about deer—gladioli are not on their “Most Favorite” dining list.

Glads do not overwinter well in the Triangle area—they can be injured if temperatures dip below 25 degrees in the garden—so consider digging up and storing the corms. This is best done in autumn after the foliage begins to die back. Shake any extra dirt off the corms, snip away spent leaves and let them cure indoors for at least two weeks. Store the sleeping glads in a mesh bag or on a screen tray in a cool, well-ventilated place such as a garage or unheated basement. Check on the corms occasionally during the winter, and if any appear to be badly decaying or bothered by bugs, discard them to prevent the problem from spreading.

While digging up your gladioli think about dividing the corms, especially if they haven’t been separated in two to three years. This will also give you the opportunity to pass along any extras to friends—another bonus because sharing is one of the things that makes gardening fun!

L.A. Jackson is the former editor of Carolina Gardener Magazine. If you would like to ask L.A. a question about your garden, contact him at

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