Plants of the Helianthemum genus are half hardy or hardy perennials that have a shrubby nature.
They may reach a height of about 30 cm, and are ideal for use in rock gardens and to fill the gaps between stones in drystone walls and paving.
The foliage of Helianthemum Plant is silver or green in colour, and they flower from spring to autumn (species specific) with flowers of orange, scarlet, yellow or bronze.
Some of the common names for Helianthemum include Sun Rose, Rock Rose and Frostweed.
Helianthemum syriacum by ch.deff.
Helianthemum almeriense by Peter M Greenwood.
Common Names: Rock Rose, Sun Rose, Frostweed, Rush Rose.
Life Cycle: Hardy perennial. Half hardy perennial.
Height: 12 inches (30 cm).
Native: Northern Hemisphere.
Growing Region: Zones 6 to 9.
Flowers: Species dependent: Spring and/or summer and/or autumn.
Flower Details: White, orange, yellow, scarlet, bronze. Five petals. Bi-coloured. Saucer-shaped.
Foliage: Evergreen. Silver, Green. Opposite. Oval.
Sow Outside: Surface. Start of spring - before the last frost, or towards the end of autumn. Spacing 5 to 18 inches (12 to 45 cm).
Sow Inside: Germination time: two to three weeks. Temperature: 70 to 75°F (21 to 24°C). Six weeks to two months before the last expected frost. Transplant outdoors following the last frost.
Requirements and care: Full sunlight. Good drainage. Poor soil, chalky soil. Can survive in dry soils. Flowers bloom for just a day, so remove the fading ones regularly. Cut back to two/thirds size once the first round of blooming has completed to encourage a second round of flowering. Propagate: cuttings can be taken towards the end of summer.
Miscellaneous: Stamens are touch sensitive.
Helianthemum plants can be grown outside by sowing seeds on the soil surface in late autumn, or before the first frost of spring. Sun Roses (and other Helianthemum) as per the name like to grow in sunny areas of the garden. it is very important that the soil they grow in has good drainage but the quality is not as important. If you plan to start growing Sun Rose seedlings indoors then they should be prepared about eight weeks in advance (put the Helianthemum plant out in the garden after the last frost of spring). It usually takes them about three weeks to germinate at a temperature of 21 to 24 degrees centigrade.
If you require more sun roses and other Helianthemum plants in the garden then take cuttings at the end of summer. Members of the Helianthemum genus are not the easiest plants to look after, they have short lived flowers that should be removed once they have finished blooming. Once the flowering has been completed then cut back about a third of the plant; so that it becomes shapely; this may lead to a second bloom.