Helen's Flower--or Helenium autumnale--is a clump-forming perennial that grows to a maximum of 4 to 6 feet tall. It attracts butterflies and is an ideal cut flower for floral arrangements. It is native to Colorado and has daisy-like flowers that bloom over a long period (from August through October). They range in color from bright yellow to orange, red and maroon.
Choose a planting site that is in the full sun. The soil needs to be fertile so if it's not, add in compost and mix it together to improve the quality.
Make sure the bed has moist soil that is well-drained. The flowers can survive in some drought but do much better with a lot of moisture.
Check the soil pH to determine if the soil is alkaline or acidic enough. Helen's Flower requires soil that is between 6.1 and 7.8 pH. Use a test kit purchased from a hardware store or garden store.
If the pH is too low: Increase the pH by 1.0 point to make it more alkaline by adding 4 oz. of hydrated lime per square yard in sandy soil. If you have loamy soil, add 8 oz. (see Resources below). If the pH is too high: Mix in 1.2 oz. of ground rock sulfur per square yard of soil to reduce the soil pH by 1.0 point, making it more acidic.
Dig holes that are spaced 36 to 48 inches from each other. The depth and width of the holes will depend on the size of the plants' rootballs.
Place the plants in the holes and cover the soil. Water every 2-3 days to retain moisture.
Deadhead the flowers to promote the growth of new ones. Pinch off the flowers once they shrivel up to die.
Divide the plants every spring to separate them. Use a trowel to dig up their roots. Transplant them.