There are several cultivars of Liatris spicata commonly used as garden plants. ‘Kobold’ is a compact variety, which has made it one of the most popular choices. From a clump of grasslike foliage, flower stalks emerge, growing up to 30 inches tall. Due to its small size, ‘Kobold’ requires less staking, as its compact stems can properly handle the weight of their large flowers. Liatris spicata is generally planted from corm-like roots or potted nursery plants in the spring. Mature corms will grow quickly and produce summer flowers in their first season. Liatris multiplies slowly by producing offset corms, and once established, colonies can last for decades. ‘Kobold’ is most economically planted by buying bare corms in bulk and planting them in the spring, at a depth of about 3 inches and a spacing of 12 to 18 inches apart. Make sure the smooth sides of the corms are facing down, with the growth eyes facing up. Liatris is also available as living plants in nursery pots, also planted in spring at the same depth as in the pot. ‘Kobold’ is a good plant for dry and medium-moisture soils, but don’t plant it in wet, boggy areas, as the corms are susceptible to rot.
Light
Liatris spicata ‘Kobold’ does best in full sun, especially during the first growing season. Choose a location that receives at least six hours of direct sunlight every day. Once established, ‘Kobold’ can tolerate shade for small periods of time although growth may not be as vigorous.
Soil
Most Liatris species are best suited for dry soils, but L. spicata ‘Kobold’ is also somewhat tolerant of moist soil, provided it is very well draining. But avoid wet, boggy soils, which can cause the corms to rot. Liatris spicata prefers soil that is slightly acidic or neutral.
Water
Drought tolerance is one of Liatris spicata ‘Kobold’s most desirable traits. The corm-like roots store water to sustain the plant during periods of drought. However, during the first growing season Liatris spicata ‘Kobold’ should be watered regularly to help it become established. After this, it usually does nicely on whatever rainfall naturally occurs. Provided the soil is well draining, ‘Kobold’ will not mind getting the same weekly watering routine as other garden plants, but more than this can lead to corm rot.
Temperature and Humidity
‘Kobold’ is hardy in USDA zones 3 to 9, withstanding extreme minimum temperatures as low as minus 30 to minus 40 degrees Fahrenheit. However, Liatris spicata does require warm spring temperatures and hot summers to grow. Not just cold-hardy, ‘Kobold’ also tolerates heat and humidity well.
Fertilizer
Fertilizing Liatris spicata ‘Kobold’ is not necessary, especially if it’s grown in healthy soil. If desired, fertilize lightly with an all-purpose fertilizer in the spring prior to new growth to give it a boost. Mixing compost into the soil each spring can also help to give the corms a good start.
Types of Liatris
In addition to ‘Kobold,’ there are several other excellent cultivars of L. spicata that are popular garden choices:
‘Alba’: This is a slightly taller cultivar at 36 inches, with white flowers.‘Floristan Violet’: This is a taller 4-ft. cultivar, but otherwise nearly identical to ‘Kobold’.‘Floristan Weiss’: This is another taller 4-ft cultivar, but with white flowers.“Callilepsis’: This variety has the traditional purple flowers on very long stems that are especially good for cutting.
Several related species are also routinely cultivated as garden plants, and are also known as blazing star:
Liatris aspera (rough blazing star): This species is native to eastern North America and produces purple flowers in August. Heights can range from 15 to 40 inches, depending on growing conditions. The stems have multiple tufts of flowers rather than a single dense tubular plume.Liatris pycnostachya (prairie blazing star) This is a native plant found somewhat further west, in the central plains. It is very similar to L. spicata, but tends to produce its purple flowers a little later, in August and September. The flower spikes can extend as much as 5 feet tall.Liatris scariosa: This North American native has a somewhat weedier appearance, with purple flower heads that are rounded and thistle-like. It is commonly used in meadow gardens and other naturalized areas, and is less suitable for formal gardens. It grows up to 4 feet. tall.Liatris ligulistylis: This is another variety well suited for meadows and naturalized garden areas. It is a wildflower with somewhat unruly thistle-like flower heads. At 1 to 3 feet tall, it is slightly shorter than L. scariosa.
Pruning
Deadheading the flower stalks after the blooms have faded will cause the plant to direct its energy to leaf growth for replenishing the roots for the following year. It will also prevent the plant from self-seeding in the garden. But some gardeners like to leave the flower stalks in place for the benefit of seed-eating birds, which may feast on them well into winter. The foliage turns an attractive golden color in fall, so this, too, can be left in place until frost kills it off.
Propagating Liatris Spicata
Liatris spicata ‘Kobold’ is easy to propagate through division and by seed. If propagating by division, the best time to divide established plants is in the spring as new growth is just emerging. A healthy plant should not be divided more than once every three to four years to help it re-establish between propagations. Here’s how to do it:
Growing ‘Kobold’ Liatris From Seed
Liatris spicata ‘Kobold’ can be easily grown from seed, though it can take some time for them to mature into flowering plants. Seeds can be started indoors in the early spring or sowed directly into the garden once the weather has warmed to about 65 degrees Fahrenheit. Germination rates improve greatly when seeds are cold-stratified before they are planted. Plant the seeds at a depth about four times the diameter of the seeds. Seeds normally take between 20 to 45 days to germinate. If starting seeds in pots, they are ready to transplant when they have developed two sets of true leaves. If started indoors early enough, you may get small flower spikes in the first year, but it is more likely the plants will not bloom until their second year.
Potting and Repotting ‘Kobold’ Liatris
Container culture is not common for Liatris, but because it is a fast-growing perennial, it’s possible to use it as a tall “thriller” species in the center of large mixed pots, surrounded by “fillers” and “spillers.” When grown this way, the corms are usually planted as annuals and discarded at the end of the growing season. However, it is possible to preserve the corms by overwintering the container in a sheltered location or by burying it up to the rim for the winter. Liatris will require a very well-draining container and potting soil, and avoid planting it with species with heavy water needs, as the corms are sensitive to being overwatered. When grown in containers, Liatris needs only light weekly watering—and only if there has been no rainfall.
Overwintering
‘Kobold’ liatris is a very hardy plant that needs no protection against winter cold. As frost kills the foliage, it can be cut away and discarded. Flower stalks can be cut away to avoid self-seeding, or leave them in place for the benefit of birds who feed on the seeds. Avoid heavy mulch layers over winter, as this can trap moisture and make the corms susceptible to rot.
How to Get ‘Kobold’ Liatris to Bloom
Individual flower stalks topped with 6- to 10-inch-long spikes of flower buds emerge from clumps of basal foliage in mid to late summer. The buds open into small purple blossoms over a period of several weeks, beginning at the top of the spike and moving downward. The blooms may remain attractive right into fall. There is very little coaxing necessary to get this plant to bloom, but you may find that young corms, or plants grown from seeds, may require a full year or more before they develop the root structure needed to support flowers. If the flower display is disappointing, it is likely because the plants are not getting enough sun. Highly alkaline soils may also lead to poor flowering. As the plant spreads and colonizes, it’s common for flowering specimens to be surrounded by smaller, non-flowering plants. These are self-seeded volunteers that simply aren’t yet mature enough to flower. If you’re patient, these small volunteers will develop into flowering plants in their second year.
Common Problems With Liatris ‘Kobold’
Although ‘Kobold’ is a shorter cultivar not as prone to flopping as taller varieties, in windy conditions you may still need to provide support for the flower stalks to keep them from falling over. This is especially true if the plant is growing in partial shade, which can cause the stalks to be leggier. Very rich soil can also cause the flower stalks to grow unusually long, requiring staking. If a ‘Kobold’ plant turns yellow and begins to die, it is likely because wet soil has caused the corm to develop rot. Such plants should be removed. Liatris is also an excellent addition to a pollinator garden, as butterflies and bees are enthralled with it.
