Gladiolus, often called “glads,” are prized for their tall, striking flower spikes that bring vibrant color to the summer garden. Proper pruning is necessary for these cormous plants to maintain their appearance, ensure the health of the underground corm, and prepare them for successful storage or dormancy. Knowing exactly when to make a cut is a two-part process, involving managing the blooms during the growing season and preparing the foliage for the end of the year. The timing of each cut directly influences the plant’s energy reserves, which are the foundation for next year’s magnificent display.
Removing Spent Blooms During the Season
The practice of removing faded flowers, known as deadheading, should begin immediately once the individual florets begin to wither. Gladiolus flowers bloom sequentially, starting from the bottom of the spike and moving upward. Removing these faded blossoms is primarily an aesthetic choice that keeps the stalk looking neat and vibrant throughout its blooming period.
The biological purpose of deadheading is to prevent the plant from diverting energy into seed production. If the spent flower remains, the plant forms a seed pod, consuming energy that should be stored in the corm for the following season’s growth. To deadhead properly, remove the entire flower spike once all the blossoms have faded, preserving the green foliage. Make a clean cut on the flower stalk just above the highest remaining leaf on the stem, leaving the sword-like leaves intact to continue photosynthesis.
The Timing of the Final Foliage Cut
The timing of the final foliage cut before winter is the most important pruning decision for the long-term health of the plant. This final cut should not occur immediately after the blooms finish because the green leaves are still actively feeding the corm. The foliage must remain for six to eight weeks after the last bloom has faded to allow the corm to store maximum energy reserves for the next growing cycle.
It is time to cut the foliage when the leaves have naturally turned yellow and begun to wilt or brown. This visual cue indicates that nutrient translocation—the movement of stored energy from the leaves down into the underground corm—is complete. Cutting green foliage interrupts this process, resulting in a weakened corm that produces smaller blooms the following year. This final cut is typically performed in late summer or early fall, often coinciding with the first light frost. Cut the foliage back to approximately one to two inches above the soil line, leaving a small stub to mark the corm’s location.
Proper Technique for Clean Cuts
The proper technique for both deadheading and the final cut involves using the correct tools and maintaining hygiene. Use sharp, clean pruning shears or sturdy scissors to make precise cuts. Dull tools crush the plant tissue, creating a ragged wound that is slower to heal and more susceptible to infection.
Sterilize blades before cutting by wiping them with rubbing alcohol or a weak bleach solution, especially when moving between plants. This minimizes the risk of transmitting fungal spores or bacterial diseases. When making the cut, angle the blade slightly rather than cutting straight across the stem. An angled cut prevents water from pooling on the wound surface, which reduces the chance of rot and disease entering the cut tissue.