Hieracium consists of a large genus of hardy perennials.
They are weedy and woody in nature and some species have an attractive silvery foliage.
They bloom from late spring through to autumn with orange or yellow flowers that are similar to those of dandelions.
They reach heights of 30 to 40 cm, making them a bigger plant for use in a rock garden.
Some of the common species of Hieracium plant used by gardeners include Hawkweed and devil's Paintbrush.
Hieracium pilosella by urjsa.
Common Names: Hawkweed, Devil’s-paintbrush, Hierakion.
Life Cycle: Hardy perennial.
Height: 12 to 18 inches (30 to 45 cm).
Native: Worldwide except Australasia and Antarctica.
Growing Region: Zones 3 to 9.
Flowers: Species dependent: Late spring through to the autumn.
Flower Details: Orange, yellow. Dandelion-like. Spatulate.
Foliage: Silver/grey. Very varied.
Sow Outside: Cover seed. Start of spring - before the last frost, or towards the end of autumn. Spacing 10 to 12 inches (25 to 30 cm).
Sow Inside: Germination time: three weeks to a month. Temperature: 50 to 60°F (10 to 16°C). Two months in advance. Transplant outdoors the last frost, or late in autumn.
Requirements and care: Full sunlight. Good drainage. Poor soil. Can survive in dry soils. Most species need to be controlled so remove flower-heads before they can set seed; as garden grown varieties of this genus, such as H x rubrum are usually grown for their foliage it may be a good idea to remove any flowers completely.
Miscellaneous: Most members of this genus are weeds and invasive, but the odd variety can be used with caution in a rock garden. The scientific name is based upon the From the Greek word for hawk (Hierax).
When growing Hawkweed and other Hieracium plants in the garden it is important to realise that they can fast become weeds, so only grow if you have the time to maintain them properly by removing flower heads before they have a chance to set seed. Hawkweed seeds should be sown into a sunny part of the garden before the last frost of early spring. Simply cover the soil once sown. Hieracium can grow in poor soil, and has a preference for a dry soil with good drainage.
You may find it easier to have control of Hawkweed if you start them off indoors. They should be prepared about two months before they are due to be transplanted in the spring before the last frost. Hieracium plants take about three or four weeks to germinate at a temperature of 10 to 15 degrees centigrade. Plant out at a spacing of about 25cm.
Once growing it is very important to keep an eye on the Hieracium plant to prevent spreading; remove all Hieracium flowers before they have a chance to set seed.