How to Grow Helianthemum Plants in your Garden

Gardener's HQ Guide to Growing Sun Rose and Rock Rose

Plants of the Helianthemum plant genus are half hardy or hardy perennials that have a shrubby nature.

They may reach a height of about 30 cm (12 inches). This makes them ideal for use in rock gardens. They are also great for filling the gaps between stones in drystone walls and paving.

Helianthemum syriacum
Helianthemum syriacum by ch.deff.

The foliage of Helianthemum Plant is silver or green in colour

They flower from spring to autumn (species specific) with flowers of orange, scarlet, yellow or bronze.

Helianthemum almeriense
Helianthemum almeriense by Peter M Greenwood.

Some of the common names for Helianthemum include Sun Rose, Rock Rose and Frostweed.

Species Specific Grow Guide for Helianthemum nummularium.

Commonly Grown Helianthemum Species

Helianthemum nummularium

Helianthemum nummularium
Helianthemum nummularium (Common Rock-rose), photograph by Ragnhild&Neil Crawford; CC.

Helianthemum canadense

Helianthemum canadense
Helianthemum canadense (Longbranch Frostweed / Canada Frostweed / Rock frost / Frostplant), picture by Aaron Carlson; CC.

Helianthemum Growing and Care Guide

Common Names: Rock Rose, Sun Rose, Frostweed, Rush Rose.
Life Cycle: Hardy perennial. Half hardy perennial.
Height: 12 inches (30 cm).
Native: Northern Hemisphere.
Family: Cistaceae.

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.

How to Grow Sun Rose (and other Helianthemum)

Helianthemum plants can be grown directly 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 of the soil is not as important.

If you plan to start growing Helianthemum seedlings indoors, then they should be prepared about eight weeks in advance. Pput the Helianthemum plant seedlings out into the garden following the last frost of spring.

It usually takes them about three weeks to germinate. This should be done at a temperature of 21 to 24 degrees centigrade (70 to 75°F).

Caring for Sun Rose - Helianthemum plants in the Garden

Helianthemum Care: If you require more sun roses / Helianthemum plants in the garden, then simply take cuttings at the end of summer.

Unfortunately, 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 completed, it is best to then cut back about a third of the plant; so that it becomes shapely; this may also lead to a second bloom.

I hope that you enjoyed this guide on how to grow Helianthemum plants. You may also enjoy the following Gardener's HQ growing guides: How to grow Rock Rose; Purple Rock Cress, Rock Purslane, and Rhodohypoxis plants.