The plants are characterized by lance-shaped foliage with stiff, upright stems. Some taller cultivars need staking. Planted in early spring, helenium plants grow quickly to a mature size of 2 to 5 feet tall and spread to 24 inches wide. Deer seldom browse helenium plants, making them a natural choice for meadows, prairies, and other naturalized areas that must accommodate wildlife. Heleniums make excellent, long-lasting cut flowers to make seasonal bouquets with other autumn beauties like sunflowers, asters, or sedum.
Light
Helenium flowers will get leggy if they don’t receive at least six hours of sun each day, but they will accept some afternoon shade, especially if the planting area is on the dry side.
Soil
Helenium plants like their soil on the acidic side, with an ideal pH range of 5.5 to 7.0. Place heleniums where they will enjoy moist conditions, but not in a boggy site. Consider a rain garden site where moisture naturally collects, such as a low-lying area or beneath a downspout. Well-draining soil is best, but heleniums are clay tolerant.
Water
Although helenium flowers resemble coneflowers and black-eyed Susan flowers, they do not share the drought tolerance of these look-alikes. In fact, heleniums like moderate to heavy moisture. A three-inch layer of organic mulch will conserve moisture and maintain the acidic soil pH heleniums like.
Temperature and Humidity
Helenium plants tolerate humidity and hot summers, but proper spacing is important to prevent fungal diseases like mildew and rust where humidity is high.
Fertilizer
Heleniums aren’t heavy feeders, and one application of a balanced flower fertilizer in the spring is enough in fertile soils. Excessive fertilizer causes lanky growth, but pinching heleniums back in the spring encourages shorter, stronger, sturdy plants and branching.
Types of Helenium
For such a seemingly simple and underused perennial, the number of helenium cultivars is surprising. Variations in flower form, height, and color allow a gardener to devote an entire plot to growing helenium if he wishes. Here are a few of the most interesting selections for your garden:
‘Adios’: Purplish-brown prominent cones; downturned petals ‘Beatrice’: Yellow petals more upward than most varieties; yellow and brown cone ‘Butterpat’: Pure yellow flowers from petals to cone ‘El Dorado’: A large brown cone flanked by a petticoat of lemon-yellow petals ‘Red-Haired Katy’: Petal color seems to shift from crimson to copper depending on the light ‘Waldtraut’: Long blooming time; orange petals flecked with gold
Pruning
Deadhead spent flowers to encourage subsequent blooming. After blooming, cut the flower stalks down to the foliage. Divide plants in the spring or fall every three to five years to keep plants vigorous.
Propagating Helenium
Helenium is easily grown from seed but can also be propagated through cuttings. Here’s how: What You’ll Need: Healthy plant, scissors, plastic bag, soilless potting mix, containers, rooting hormone (optional) Where to Cut: Cut with scissors just below a node on a soft, green stem (cutting should be about 4 to 6 inches long). Maintaining the Cutting: Remove the bottom few leaves, dip the stem in water then in rooting hormone (if desired), and slide stem about 2 inches into a container of potting mix. Keep warm and moist but not soggy. When to Plant the Cutting: In 3 weeks, transplant the cutting into another pot or the ground.
How to Grow Helenium from Seed
If you choose seed starting to get a large colony of helenium growing quickly, sprinkle the seeds liberally on moist ground but don’t cover the seeds because they require light to trigger germination. Plants will germinate in about two weeks at room temperature.
Overwintering
After the first frost, spread a thick layer (about 6 inches) of hay or mulch over your helenium bed. In the spring, as soon as the frost danger has passed, remove the insulating layer.
How to Get Helenium to Bloom
With adequate moisture and sunlight, heleniums are enthusiastic bloomers in the late summer. Their flowering can be encouraged to continue into fall by deadheading.
Common Problems With Helenium
Helenium plants are renowned for their hardiness and disease resistance, but if they are crowded—especially in shaded areas—they can suffer from powdery mildew or leaf spot.
