Helianthemum

( hee - lee - ANTH - em - um )

At-A-Glance Information

Commonly called Sunrose or Common Rockrose, this genus of evergreen perennial shrubs includes species that require full sun and moderate water to perform well in the garden. Native to Europe and Asia Minor, all forms grow to about 6-8 inches tall and 3 feet wide. Depending on the species leaves can be grey on both sides, or green on top and fuzzy grey underneath. Single or double white, red, apricot, orange, yellow, pink, rose, peach, or salmon colored flowers bloom in midspring to early summer. These flowers are ideal for planting on slopes, in containers, or in coastal landscapes, and are also used as a groundcover.

Helianthemum Species and Varietals

Helianthemum is a member of the plant family Cistaceae and includes 110 species. The genus name is derived from the Greek words for sun (helios) and flower (anthemom).The best growing zones for these flowers are USDA hardiness zones 5-9. To find your zone, click here: Zone Map.

Helianthemum almeriense (Jarilla, Mata Turmera, Tormera)
This species grows from a very woody base and produces green-grey leaves and white flowers with yellow centers. Individual plants in this species reach up to between 3 and 24 inches tall when mature and in bloom. This species is native to the Iberian Peninsula and Morocco in northern Africa.

Helianthemum nummularium (Common Rock Rose)
This low-growing plant is native to most of Europe, and forms an evergreen trailing plant with loose terminal clusters of bright yellow flowers from May through July. Central stamens are sensitive to touch. Individual plants reach up to between 6 and 12 inches tall with a 2-3 foot spread. Popular garden cultivars are listed and described below:

'Amy Baring'
With bright orange-yellow blooms. 5-6 inches tall and 1-2 feet wide.

'Belgravia Rose'
With rose-pink blooms and blue-green leaves. Compact to 6-11 inches tall and 2-4 feet wide.

'Fire Dragon'
Copper-red flowers contrast against grey-green foliage. To 4-10 inches tall and 12-24 inches wide.

'Helenfield Brilliant'
With bright scarlet-orange flowers and grey foliage. 6-12 inches tall and 18-24 inches wide.

'Jubilee'
With double pale yellow flowers.

'Mrs. C.W. Earle'
Double bright red blooms and green foliage.

'Raspberry Ripple'
White blooms have pink-red blushing and striping.

'Rhodanthe Carneum'
Soft pink flowers against grey-green foliage.

'St. Mary's'
White flowers with yellow centers and light green foliage.

'The Bride'
With pure white flowers against green leaves.

'Wisley Primrose'
Yellow flowers and grey-green foliage.

Caring for Helianthemum

hese shrubs do not need fertilizing. Deadhead as flowers fade, and after flowering period give the shrub a light pruning to keep it looking neat. These shrubs will probably need to be replaced every few years, even if pruning is kept up.

Plant Helianthemum shrubs and groundcovers in a space that receives full sun; ideally, they appreciate between 6 and 8 hours of sun each day. When these plants are grown in lower light, they will not flower as profusely and can become leggy. Space 2-3 feet apart if growing as a groundcover. Ensure that soil is well-draining, amended with plenty of rocks and sand, and has a pH of between 6.6 and 8.5 (slightly acidic to alkaline). If local soils do not drain well, make sure to amend the planting area with plenty of organic compost, perlite, and rocks or sand before installing. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water new plantings regularly and deeply as they establish a strong root system in their new home; they take about a year to acclimate fully. Once established, they are considered drought-tolerant plants and can get by on rainwater alone for much of the year with supplemental waterings in extended periods of drought.

Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. Pruning is simple; remove any damaged, diseased, or dead foliage at any time during the growing season, and remove spent flowers to neaten up the appearance of plants and encourage reblooms. Give the shrub a light pruning to keep it looking neat after flowers fade for the year. Pinch back plants when they are young to encourage a bushier habit. Helianthemum plants can survive in the landscape for between 3 and 5 years. They form a very woody base over time, reaching their full size in just 1-2 years.

Growing Helianthemum in Containers
Helianthemum shrubs are wonderful in the ground, but can also be grown in containers. Choose a container that is at least a few inches wider and deeper than the nursery pot or root ball. Ensure that the pot has adequate drainage holes on the bottom to allow for excess water to flow away. Fill with a well-draining potting mix amended with organic material and perlite, and top with a layer of mulch to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water regularly as the plant establishes itself in its new home. Once established, waterings can be lessened. Helianthemum plants grown in containers will need more frequent irrigation than those grown in the ground. As a general rule of thumb, water whenever the top few inches of soil feels dry to the touch. Pinch back young plants to encourage a bushier habit. Prune to remove dead, damaged, or diseased foliage at any time during the growing season. Every few years, check the bottom of the pot to ensure that the plant is not outgrowing its root space. If roots are growing through the drainage holes in the bottom of the container, it is a good indication that it needs to be potted up; choose a slightly larger container and repot.

Propagation

Helianthemum can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your Sunrose, follow the instructions below:

Propagating Helianthemum by Cutting

Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. A good substrate for propagation of cuttings is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Helianthemum by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds.
Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 7-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.