With multiple flowers decorating 2- to 6-foot-tall spikes, gladioli (Gladiolus spp.) are often cultivated solely for cut flowers in the home during spring and summer. Preferring U.S. Department of Agriculture plant hardiness zones 6 through 10, these perennials take about three months to grow blossoms from a planted bulb, or corm. Gladioli, however, can rebloom after cutting if the bulb is large enough to supply the necessary energy for another spike growth.
Corms are storage organs that house nutrients for future flower spikes. Gladioli use their stored energy to form new growths on the old corm; this new growth is the flower spikes seen this season. Plants harness new energy from photosynthesis as leaves emerge from the corm. Your gladioli rebloom after cutting if the corm is larger than 1 inch wide. These corms are often categorized as size numbers 1 through 3, as well as jumbo sizes larger than 2 inches across. Corms smaller than 1 inch wide do not have the stored energy necessary for more than one flower spike. Once you remove the spike, the corm must gather its energy over time to be ready for next season.
Proper Cutting Technique
Remove a flower spike for indoor decoration when you see the first flower beginning to open. When you place the spike in water, the remaining flowers slowly open over time for a long-lasting centerpiece. To preserve your plant's health, cut the spike several inches above its base at an angle with clean gardening shears. The angled cut allows the spike to take up ample water in a container. A clean and sterile cut also prevents disease from setting into the open wound on the plant itself. If your corm has the energy to rebloom, an entirely new spike appears as the remaining spike end dies back.
Do not remove any leaves on your gladioli as you cut flower spikes away. In a preferred full sunlight location, these leaves photosynthesize until they are papery and yellow. This energy production becomes stored in the corm for next year's blossoms. Unlike other bulb plants, gladioli do not require extensive chilling between growing seasons. They can remain in the ground until next year without harm. You will notice, however, that the flower spikes become limited as the corm ages. For example, a jumbo corm that produces an average of three flower spikes a year may slowly dwindle to one spike after six years pass. Discard your old corms when they are not vigorous.
Your gladioli cannot rebloom after cutting if their planting location becomes soggy. In fact, your corms may fail to flower at all if the area is consistently wet. Soggy soil makes corms vulnerable to rot, such as from fusarium fungi. Do not overwater your corms. Only water the area when sprouts emerge. Dormant corms do not need extensive moisture. Periodically dig your corms between growing seasons and cultivate the soil with organic matter to maintain a friable structure that drains well.
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