From our perspective as gladiolus plants, the period after our spectacular blooms fade is a critical time. It's when we shift our energy from the showy task of reproduction (flowering) to the essential work of survival and preparing for next year's display. Your actions during this phase directly impact our health and our ability to bloom for you again. Here is a detailed guide to our post-bloom needs.
Once our flowers wither and the petals drop, please do not cut down our entire foliage. Our tall, sword-like leaves are not just for show; they are our solar panels. While we were blooming, a significant amount of the energy we produced was diverted to the flower spike. Now, with that task complete, we can redirect all our photosynthetic power back to our underground storage organ: the corm. The corm is a modified stem that serves as our lifeline through dormancy. Over the next several weeks, as our leaves remain green, we are actively absorbing sunlight and nutrients, converting them into carbohydrates, and swelling the corm for the future. Cutting the leaves too early is like taking away our food supply before we've stored enough for winter.
During this period of leaf-generated energy, remarkable changes are happening below the soil. The original corm that you planted is actually being depleted; it sacrificed itself to produce the flower spike and leaves. However, a new, larger replacement corm is forming on top of the old one. Additionally, tiny new corms, called cormels, may develop around the base. This is how we multiply. Your role is to support this process. You can cut off the spent flower spike about halfway down the stem to prevent us from wasting energy on seed production (unless you wish to collect seeds, which is a much longer process). But, you must allow the leaves to remain intact and functional until they begin to yellow significantly, typically 4-6 weeks after blooming.
Whether you need to dig us up depends on your climate. We are tender perennials and cannot survive freezing temperatures in the ground. If you live in a region where the soil freezes solid in winter (generally USDA zones 7 and colder), you must lift our corms in the fall to store them indoors.
Wait until the foliage has turned yellow or brown, signaling that we have entered dormancy and energy transfer to the corm is complete. Carefully dig us up, shake off the loose soil, and cut the stems back to within an inch or two of the corm. Leave us to dry (cure) for a few weeks in a warm, well-ventilated place. This drying period is crucial to prevent rot during storage. Once dry, you can gently remove the old, shriveled corm from the base of the new one and discard it. Also, you can save the small cormels, though they will take a couple of seasons to reach flowering size.
If you live in a warmer climate (zones 8 and above), you may leave us in the ground over winter. Simply cut the dead foliage down to the soil level after the first frost and apply a protective layer of mulch to insulate the soil.
For those corms that are lifted, proper storage is our key to surviving until spring. After curing and cleaning, place us in a breathable container, such as a mesh bag, a paper bag, or a crate with good air circulation. We need to be kept in a cool, dark, and dry environment, with ideal temperatures between 35-45°F (2-7°C). A basement, unheated garage, or a cool closet is perfect. Please do not store us in an airtight plastic bag, as this will trap moisture and cause us to mold and rot. Check on us periodically through the winter to ensure we remain firm and healthy.
