From my perspective as a gladiolus, my entire purpose is to put on a spectacular floral show. To thrust my tall flower spike high into the air and unfurl a succession of vibrant, large blooms, I require a significant amount of energy. This energy comes from the sun, but the building blocks for my growth come from the soil. I am a heavy feeder, meaning I deplete soil nutrients quickly. My main requirements are a balanced diet of Nitrogen (N), Phosphorus (P), and Potassium (K). Nitrogen supports the development of my strong, green leaves and stem—the crucial support system for my heavy flower spike. Phosphorus is absolutely vital; it is the element that drives the development of my extensive root system and, most importantly, my magnificent blooms. Potassium (Potash) ensures my overall vigor, helping with disease resistance and the movement of water and nutrients throughout my system.
Before you even plant my corm, please prepare my home. I need well-draining soil that is rich in organic matter. As you prepare the bed, work in a balanced, slow-release granular fertilizer, such as a 5-10-10 or a 6-12-12 formulation. The higher middle number (Phosphorus) is key here. Mixing this into the soil at planting time gives me a steady, foundational source of nutrients right from the start. It encourages my roots to establish themselves strongly, which is the first and most critical step towards a healthy life and a spectacular bloom. Incorporating well-rotted compost or manure at this stage is also immensely beneficial, as it improves soil texture and provides a gentle, natural nutrient source.
Once I have sprouted and am growing vigorously, producing several sword-like leaves, my needs shift. I am now putting a tremendous amount of energy into developing my flower spike. This is the time for a second feeding. When my stalk is about 6-8 inches tall and again when the flower spike begins to show its first hint of color, I would greatly benefit from a side-dressing of a balanced liquid fertilizer. A water-soluble formula like 10-10-10 is ideal. Apply it to the soil around my base, taking care to avoid getting it on my leaves to prevent burn. This mid-season boost provides the immediate nutrients I need to develop a strong, tall stalk and large, well-formed buds.
Your care for me should not end after my final bloom has faded. While the show above ground is over, what happens next is critical for my performance next year. After you deadhead my spent flower spike, I begin the vital work of regenerating my corm for the next season. I need energy to create a new, larger corm on top of the old one and to develop cormlets. Please apply a fertilizer high in potassium, such as a 0-0-5 or a similar formulation, about six weeks after I finish blooming. This final feeding, coupled with allowing my leaves to remain until they yellow and die back naturally, allows me to photosynthesize and store enough energy to ensure that I can return with another spectacular display for you next year.
