The rockrose is a popular and easy-care flowering plant for stone and gravel gardens, for greening wall crowns and for planting beds. The low subshrub is available in numerous varieties and colors. In addition to bright yellow and orange flowering shapes, there are also red, white and pink varieties. The tirelessly blooming rock rose shows its true splendor only with the right care. Here are tips for planting and care.
Profile of rockrose:
Scientific name: Helianthemum
Plant family: rockrose / rock-rose / rock rose family (Cistaceae)
Other names: rock rose, rock-rose, sunrose, rushrose, frostweed
Sowing time: March
Planting time: spring (best) or autumn
Flowering period: May to July
Location: sunny
Soil quality: gritty to loamy, calcipholous, nutrient rich, humus rich
These information are for temperate climate!
Use in: ground cover, group planting, planters, dry stone walls, flower garden, Mediterranean garden, rock garden, potted garden
Winter hardiness: hardy, USDA Plant Hardiness Zones: 6 (-23 °C / -5 °F)
Bee and insect friendly: Yes
Plant characteristics and classification of rockrose
Plant order, origin and occurrence of rockrose
Rockroses (Helianthemum hybrids) belong to the family of rockrose family (Cistaceae). The small shrubs have a perennial character and are particularly at home in the Mediterranean and Asia Minor.
Characteristics of rockrose
Plant
The Helianthemum hybrids are dwarf shrubs because the thin shoots become woody and do not pull in in winter, as is typical for perennials. The rockroses reach a maximum height of 30 centimeters (12 in), but over time they form broad, blooming polster.
Leaves
The delicate rockroses have wiry, slightly woody shoots with narrow, elongated, dark or gray-green leaves. These sit opposite on the stems. The subshrubs are usually evergreen or semi-evergreen.
Blossoms
In early summer, the cup-shaped flowers appear arranged in racemes. They have five wide open petals, which can be colored white, yellow, orange, pink or red, and numerous yellow stamens in the center of the flower. The flowers open in the early morning and only bloom for one day. For this, flowers are formed en masse: New buds open every day for weeks. Helianthemum hybrids with double flowers can now also be found on the market, but double flowers don’t serve as food for insects or bees.
Rockrose – cultivation and care
Location
As one of the names suggests, sunroses like a full sun. The flowers only open in good weather and always stretch towards the sun.
Soil
Rockroses need a dry, well-drained, nutritious and calcareous soil with sand and gravel.
Planting rockrose
Mix some compost into the excavation when planting rockroses. In addition, you should then water and mulch the plants vigorously so that the moisture remains in the soil. Mixas fine gravel as possible to the mulch material.
Planting time
Plant the young rockroses in the bed in spring. Unless you do not overwinter the plants, you can pre-cultivate them on the windowsill from March and then put them directly in the bed. Specimens planted between the end of May and the beginning of June also survive the coming winter better, since they were able to grow vigorously in the months in between. Alternatively, autumn planting is also possible, provided the weather is still mild and frost-free. In rough locations, both freshly planted and overwintering rock roses can use light winter protection.
Planting distance
In general, the ideal planting distance is 25 centimeters (10 in), which is why you should plan about ten plantlets per square meter (10 sq ft.) of planting area. However, the distances can vary depending on the selected variety.
Watering
Water the sunroses moderately but regularly – this will promote flowering. However, while the plants react without any problems to dry phases, they do not tolerate waterlogging at all. Although, if the dry periods last too long, the flowers will wither. Calcareous water is best for watering, which is why you should use fresh, but not ice cold, tap water.
Fertilization
If you have planted the rockrose in a location with nutrient-rich soil and maybe even mixed compost into the plant substrate, fertilization is not necessary at first. However, you can fertilize if necessary, for example if the blooming is rather poor due to the likely lack of nutrients. However, potted plants and specimens planted on nutrient-poor subsoil should be supplied with a liquid fertilizer or liquid compost for flowering plants every four weeks between April and August.
Pruning
During flowering, you should regularly cut off dead branches to suppress the formation of seeds and instead encourage the sunrose to continue flowering. After the main bloom – but at the latest in September – you also prune the plants vigorously in preparation for winter. The clippings are very suitable for composting.
Propagation
During the summer months, rockroses can easily be propagated by cuttings or layer, in spring or autumn older plants can also be divided well.
By sowing
If you do not cut off the faded flowers, this will develop seed-bearing capsule fruits. You can harvest these in autumn and use them for sowing. Allow the seeds to dry for several days and keep them cool and dry in an easily sealable container. However, the rockroses obtained from them are not pure, so their color can be different. Here’s how to grow the young seedlings:
- From March, sow the seeds in flat seed trays
- Fill with potting compost
- Place in a cool spot at 5 to 10 °C / 41 to 50 °F
- Cover the seeds very thinly with substrate
- Keep slightly moist at all times
- Prick out as soon as the first cotyledons appear
- Now take care of the plants separately in small pots
- A temperature of around 15 ° C / 59 °F is now ideal
- From the end of May, the young plants can planted outdoors
By Cuttings
Rockroses can be propagated just as easily by cuttings. To do this, cut 5 to 10 centimeters (2 to 4 in) long, non-blooming and half-lignified shoots in summer. Put them in a small pot filled with potting compost and moisten them slightly. Put a translucent plastic bag or a cut plastic bottle over it to create a warm, humid climate for root growth. Alternatively, the cuttings can be rooted in a water glass.
The young plants should be kept cool but frost-free and should not be put outside until the following spring.
By division
In spring and autumn it is also possible to split larger rockroses clusters. Proceed as follows:
- Dig up a vigorous and healthy plant
- Use a clean, sharp knife to cut them into several smaller parts
- Each part must have several shoots and buds
- Plant the parts separately at a new location
- Water well
Diseases and pests
Rockroses are robust and are hardly affected by pests, occasionally aphids occur on the plants. However, they can be easily removed by spreading nettle slurryfor some time.
Wintering
Rockroses are hardy down to -23 °C / -5 °F.
Use in the garden
In gardens, you will find a number of cultivated varieties of many different flower colors. The shallow-rooting plant are well suited for wall crowns, stone joints or gravel beds in full sun. The dainty summer bloomers also look good in permanently planted tubs together with other polster plants. As perennials in the rock garden, Serbian bellflower (Campanula poscharskyana), low asters or the blue fescue (Festuca glauca) are ideal. The flowers of the rockroses are very popular with insects and especially provide bees with plenty of pollen.
Varieties
There are around 175 different types of rockroses, with primarily using hybrids in the garden. While the species such as the common rockrose (Helianthemum nummularium) blooms mainly yellow, the cultivated forms are available in numerous colors. The most beautiful variants for the home garden include the following:
- Common rockrose (Helianthemum nummularium): blooming yellow, robust, up to 30 centimeters (12 in) high
- ‘Annabell’: numerous pink, single flowers
- ‘Rose Glory’: distinctive dark pink, single flowers
- Alpine rockrose (Helianthemum alpestre): blooming yellow, robust, up to 15 centimeters (6 in) high
- Garden rockrose (Helianthemum x cultorum): different colors and shapes
- ‘Ben Fhada’: bright yellow flowers with an orange center, polster-forming, evergreen, stature up to 20 centimeters (8 in)
- ‘Bronze carpet’: brown-orange flowers, covering the ground, forming clumps, growing to 15 centimeters (6 in)
- ‘Cerise Queen’: bright purple, double flowers with a yellow center, wintergreen, stature up to 20 centimeters (8 in)
- ‘Cheviot’: apricot-colored flowers, filigree growth, wintergreen, polster-forming
- ‘Cornish Cream’: vanilla-yellow, delicate flowers with a strong yellow center, wintergreen, clump-forming
- ‘Bullfinch’: deep red flowers with a pink border and yellow center, clump-forming, stature up to 15 centimeters (6 in)
- ‘Golden Queen’: bright yellow flowers with an orange center, richly blooming, wintergreen, stature up to 20 centimeters (8 in)
- ‘Lawrensons Pink’: purple-pink, semi-double flowers with a yellow center, clump-forming, wintergreen, robust, stature up to 20 centimeters (8 in)
- ‘Raspberry Ripples’: two-tone pink and white flowers, winter green, polster-forming, eye-catching
- ‘Ruby’: dark red, double flower, wintergreen, stature up to 20 centimeters (8 in)
- ‘Ruth’: red-brown flower, gray-green foliage, cushion-forming, wintergreen
- ‘Snow Queen’ / ‘The Bride’: bright white flowers with a yellow center, develops dense polster, stature up to 25 centimeters (10 in)
- ‘Sterntaler’: deep yellow flowers, compact, strongly clumping growth, height up to 15 centimeters (6 in)
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