From our perspective as gladiolus plants, successful cultivation that meets your goal of continuous blooms requires an understanding of our internal biological clock and growth cycle. Our life begins as a corm, a swollen underground stem that stores the energy needed to launch our growth. Timing your plantings is the single most important factor in achieving a season-long display of our flower spikes.
Our fundamental growth trigger is soil temperature. We will remain dormant if planted in cold, wet soil, as it can cause us to rot. We require soil that has warmed to at least 55°F (13°C). Our active growth thrives in temperatures between 60-80°F (15-27°C). From the moment you plant us, our internal processes initiate root development first, followed by the push of a green shoot toward the sun. The timeline from planting to flowering typically takes 60 to 90 days, depending on the variety and weather conditions. This variable maturation rate is the key mechanism you can use for succession planting.
To achieve a non-stop display, you must not plant all of us at once. Instead, employ a staggered planting schedule. This works with our natural development rates to ensure that as one group of us finishes its bloom cycle, another group is just reaching its peak.
Begin planting our corms in the spring, approximately two weeks before your last expected frost date. The soil is warming adequately by then, satisfying our primary requirement.
First Planting: Plant the first batch of early-season varieties as soon as the soil is workable and has reached 55°F. This group will establish roots and be ready to bloom in early summer.
Successive Plantings: Every one to two weeks after the initial planting, introduce another batch of our corms. Continue this pattern until early summer. For example, if your last frost is in mid-April, you would plant groups in mid-April, late April, mid-May, and early June. This staggered approach means we will mature and send up our flower spikes sequentially throughout the season.
Final Planting: Make your final planting about 12 weeks before your first expected fall frost. This allows us enough time to complete our growth cycle and provide a final show of color before the cold weather arrives.
While timing is paramount, other factors influence our performance. Plant us in a location with full sun; we require at least six hours of direct sunlight to fuel the development of strong stems and large flowers. Ensure the soil is well-draining to prevent our corms from sitting in water. Provide support for our taller varieties, as our heavy flower spikes can be vulnerable to wind and rain. After each of us has finished flowering and our foliage begins to yellow, you can dig up our corms for storage over winter, ready to be replanted the following spring.
