Helenium Autumnale [Hel-EE-nee-um, Aw-tum-NAH-lee] is a flowering plant from the Asteraceae family.
This plant is native to North America and southern Canada.
It commonly grows in abandoned fields, badly drained pastures, marshes, fens, soggy thickets, open moist woodlands, moist wooded areas, as well as along ditches, ponds, and streams.
The common names of this plant include:
- Autumn Sneezeweed
- Fall Sneezeweed
- Large-Flowered Sneezeweed
Size & Growth
This plant is a perennial herb growing around 4’ feet high. The leaves of sneezeweed are narrowly oval to lance-shaped and have a few teeth.
The stems of this plant are slightly hairy and can grow as tall as 5’ feet or more. The leaves are produced on the plant’s stem alternatively.
Flowering and Fragrance
During late fall and summer, numerous yellow 2″ inch in diameter daisy-like flowers are produced.
The flowers have a unique wedge shape and are three-lobed at the tip. It also has a dull yellow, dome-shaped, and prominent center risk.
Light & Temperature
Helenium Autumnale loves the sun, and why the ideal growing location is in full sun. The flowers start getting leggy if they don’t get a minimum of six hours of full sun every day.
However, this plant tolerates partial shade, particularly if the conditions are dry.
Helenium also tolerates hot summers and humidity but requires sufficient spacing to prevent fungal diseases, like rust and mildew, which occur under high humidity.
Watering and Feeding
This plant prefers moderate moisture, but needs more water in dry conditions.
It is best to provide the plant with an organic mulch of about 2” inches to conserve moisture and maintain ideal pH soil levels.
Feed plants during the early spring growth period. Avoid feeding plants with excess fertilizer or rich soils as this results in fewer flowers and extensive foliar growth.
Soil & Transplanting
For optimal growth, this plant needs moist soil. Many new hybrids tolerant drier soils.
Helenium autumnale likes acidic soils, with pH levels of 5.5 to 7.0.
Grooming and Maintenance
This plant must be staked for preventing any potential flopping of the taller stems.
Pinch back new growth during the late spring for encouraging a sturdier, shorter plant with floriferous growth of flowers.
This plant might also get ragged foliage before they start to bloom.It is best to trim off the stems during early spring before the growth season.
How To Propagate Helenium Autumnale
Plant propagation is done through seeds, but it is ideal for propagating by tip cuttings or divisions. This should ideally be done during the early spring.
- When planting seeds, it is best to sow seeds during the spring and prick out the seedlings when they are large enough.
- Place the seedlins in individual pots and keep them in the greenhouse for the first winter.
- During early summer, start planting them in their permanent position.
- Basal cuttings should also be taken during the spring season.
- Take cuttings from the base of the plant and put them in a frame during June and July.
- Harvest them once they grow 4” – 6” inches tall.
- Put them in individual pots and place them under light shade till they start rooting.
Helenium Sneezeweed Pest or Diseases
Helenium doesn’t face any serious disease or pest problems. However, the foliage is vulnerable to rust, leaf spot, and powdery mildew.
The seeds, flowers, and leaves of sneezeweed are said to be poisonous to humans if consumed in high quantity.
The symptoms include:
- Breathing difficulties
- Elevated pulse and temperature
It might also result in intestinal and gastric irritation, which could prove fatal.
This plant also has sesquiterpene lactones, which might result in skin rashes in some cases and prove poisonous to dogs and fish.
The chemicals of this plant might be poisonous to livestock, especially sheep.
The most popular garden use of this plant is in wild gardens, cottage gardens, and prairies.
Mature, almost dried flower heads are transformed in the powder form to treat headaches and colds.