Liatris, widely known as Blazing Star or Gayfeather, is a striking North American perennial prized for its tall, bottlebrush-like purple flower spikes. Although often called a “bulb,” the planting unit is technically a corm—a solid, swollen stem base. The number of floral spikes produced is not fixed but is directly tied to the size and maturity of the corm at planting. Understanding this relationship is key to successfully growing this popular garden plant.
The Direct Answer: Yield Per Corm Size
The number of flowering stalks a Liatris corm produces in its first year is determined almost entirely by its diameter. The largest, most mature corms have enough stored energy to produce multiple spikes immediately. A small corm (less than one inch) typically yields only one to two slender flower spikes in the first season. Medium-sized corms (one to one-and-a-half inches) generally develop two to four spikes, while the largest corms, often “golf-ball size,” reliably yield four or more robust spikes. First-year plantings will generally produce fewer spikes than the same plant will in subsequent years after it has established a stronger root system.
Maximizing Flower Production Through Planting
To ensure the Liatris corm reaches its maximum potential spike yield, proper planting technique and site selection are both necessary. The corm should be planted with the slightly pointed growing tip facing upward and the flat side facing down into the soil. A planting depth of two to four inches below the soil surface provides the necessary insulation and stability for the developing plant.
Correct spacing between corms is also an important factor in maximizing the number of floral spikes. While Liatris can be planted as close as six to eight inches apart for a dense, massed look, spacing them 12 to 15 inches apart allows each individual plant more room to grow and develop a greater number of spikes. This wider spacing also improves air circulation around the plants, which helps to prevent fungal issues.
Selecting the right location is paramount, as Liatris requires at least six hours of direct sunlight each day to produce strong, straight stems and abundant flowers. The plant needs well-draining soil, ideally a sandy or loamy mixture, because the corm is highly susceptible to rot in wet, heavy conditions. Placing the corm in poorly drained soil will likely result in zero yield due to the destruction of the underground storage organ.
Ensuring Future Blooms: Liatris Corm Multiplication
The single corm initially planted functions as a temporary storage organ. The original corm expends its energy to produce the first year’s spikes and foliage, slowly shriveling as the season progresses. Before dying back, the plant produces smaller offshoot corms, known as cormels, around its base. These cormels are miniature copies of the mother corm and must mature underground for two to three years before producing their own flower spike. As this cycle repeats annually, the Liatris patch becomes a dense cluster of flowering plants, significantly increasing the total number of spikes in that area.
To maintain the vigor and health of the planting, division of this growing corm cluster is beneficial every three to four years. If left undivided, the center of the clump can become overly crowded, causing the oldest corms to die out and resulting in fewer flowers. Division can be performed in the early spring as new growth emerges or in the fall after the foliage dies back, separating the new cormels to create entirely new, productive plants.