Gladiolus, often called the sword lily due to its tall, upright form and pointed leaves, is a popular choice for garden displays and cut flower arrangements. These summer-blooming perennials are prized for their spectacular flower spikes, which emerge in a brilliant spectrum of colors. While a garden can feature gladiolus blooms throughout the summer season, typically starting in mid-summer, the duration of the bloom from a single planted corm is much shorter and highly variable depending on variety, environment, and care.
The Duration of a Single Gladiolus Spike
The flower spike produced by a single gladiolus corm offers a concentrated period of color, typically remaining in bloom for approximately seven to fourteen days. This duration is achieved through the sequential unfolding of individual florets along the tall stem, rather than a simultaneous burst of color.
The blossoms open progressively, starting with the lowest flowers and working their way upward toward the tip. As the upper buds open, the lower, spent flowers begin to fade. Environmental factors significantly impact this lifespan; cooler air temperatures slow the plant’s metabolism and extend the blooms, while intense heat and harsh sunlight cause them to wilt and fade faster.
For cut flowers, vase life is maximized by harvesting the stem when only the lowest one or two florets have opened. Removing the top one or two unopened buds before placing the spike in a vase encourages the remaining flowers to open more uniformly. Consistent water availability is crucial, as drought stress quickly shortens the lifespan of the entire flower spike.
Staggered Planting for an Extended Season
Since a single gladiolus corm flowers only once for a brief window, horticulturists use staggered planting to achieve a continuous display. This technique relies on the plant’s growth cycle, where blooms typically appear 70 to 100 days after the corm is planted. By planting successive batches, a gardener ensures new flower spikes emerge just as earlier ones finish blooming.
The process involves planting the first batch of corms in the spring, immediately following the last expected frost. Subsequent plantings are scheduled at regular intervals, generally every 10 to 14 days, continuing until early to mid-summer. This methodical approach ensures a constant succession of flowering plants from mid-summer until the first autumn frost.
To maintain a steady supply, plant a manageable number of corms (five to seven) during each interval. This creates a dedicated cluster of flowers that bloom together, followed by the next cluster two weeks later. This schedule stretches the short lifespan of the individual spike into a full-season floral performance, allowing for continuous harvesting.
Post-Bloom Maintenance and Corm Care
Once the last flower on a spike has faded, post-bloom maintenance begins with deadheading, which is the removal of the spent flower stalk. This prevents the plant from expending energy on producing seeds. Redirecting resources back toward strengthening the underground corm is essential for future blooms.
When cutting the stalk, leave as much foliage as possible, typically four pairs of leaves, which function as the plant’s energy factories. The leaves must remain until they naturally yellow and wither. During this time, they photosynthesize and transfer vital energy reserves to the corm for its survival and bloom potential the following season.
In regions where winter temperatures fall below freezing, the corms are not hardy and must be dug up before the ground freezes. After lifting, dry the corms in a warm, well-ventilated area for approximately three weeks. Once dry, remove the old, shriveled corm at the bottom. Store the new, plump corm in a cool, dark place (ideally 35°F to 50°F) until spring planting.