The sun rose (bot. Helianthemum) is a popular and easy-care flowering plant for rock and gravel gardens, for greening wall crowns and for bed planting. The low-growing subshrub is available in numerous varieties and colors; in addition to bright yellow and orange flowering forms, there are also red, white and pink variants. However, the tirelessly blooming sun rose only shows its true splendor with appropriate care.
What are the sunflower care requirements?
The sun rose (Helianthemum) is an easy-care, low-growing plant, ideal for rock and gravel gardens, greening of wall crowns and bed planting. It blooms tirelessly in a variety of colors, requires a sunny location and well-drained, calcareous soil.
Origin and distribution
Sunflowers (bot. Helianthemum) are a genus of dwarf and subshrubs from the rockrose family (Cistaceae), comprising around 175 different species. The pretty, perennial to cushion-like plants are originally native to the Mediterranean and Asia Minor, but are generally hardy here too.
The genus owes its name to the flowers' ability to align themselves with the position of the sun and to close in the dark and at cool temperatures of less than 20 °C. The yellow color of the flowers, which is characteristic of the wild species, also refers to the sun, while the hybrid forms now also have numerous other colors.
Usage
Whether wild or hybrid, the shallow-rooted sun rose is ideal for rock and gravel gardens as well as for greening stone joints and wall crowns. In the garden bed or in the border, the low plant works best in the foreground and with taller perennials as an accompaniment; in the rock garden it harmonizes particularly with summer bloomers such as cushion bluebells (Campanula poscharskyana) and summer asters (Callistephus chinensis) as well as grasses such as blue fescue (Festuca glauca). Furthermore, sun roses are suitable for planting in pots and balcony boxes, preferably in combination with other upholstery perennials.
Appearance and growth
Sunflowers are dwarf or subshrubs that remain low and form dense cushions. Their shoots do not shrink in winter - as is usual for perennials - but instead become woody over time. Depending on the variety, the plants grow between 15 and 30 centimeters high and form richly flowering, dense cushioned carpets. On the wiry, slightly woody shoots of the delicate sun roses there are numerous elongated, narrow, dark or gray or silver-green leaves, depending on the variation. Most species and varieties are at least wintergreen, some are also evergreen.
Flowers and flowering time
The cup flowers of sun roses, arranged on panicles, appear in early summer and last until August for most varieties. The five wide-open petals are usually colored yellow, but can also be white, orange, pink or red in various shades. There are also two-tone varieties with a differently colored flower center. There are always many yellow stamens in this that stand out noticeably. Sunflowers produce flowers en masse over a period of weeks: new buds appear every day, open early in the morning and usually only bloom for one day. In addition to the simple cup flowers typical of the species, hybrid varieties with semi-double and double calyxes are now also available commercially.
Toxicity
The sun rose is not poisonous to humans or animals. Instead, it is sometimes used in naturopathy, especially in Bach flower therapy.
Which location is suitable?
As their name suggests, sunflowers feel most comfortable in a warm, full sun location. After all, the flowers only open when there is sunshine and temperatures above 20 °C.
Soil / Substrate
Sunflowers thrive best on rather dry, sandy to gravelly, well-drained and moderately nutrient-rich soils. The plants also need a calcareous subsoil for he althy growth. It is best to plant Helianthemum cultivated in planters in potting soil or potting soil mixed with plenty of sand, perlite or similar. Give preference to compost-based varieties.
Planting sunflowers correctly
When planting the sun roses, mix some compost into the excavation. You should also water the plants heavily and mulch afterwards so that the moisture remains in the soil. Mix the mulching material with as fine gravel as possible.
Planting time
Plant the young sun roses in the bed in spring. If you don't overwinter the plants, you can grow 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 because 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 harsh locations, both freshly planted and overwintering sunflowers can tolerate light winter protection.
Planting spacing
In general, the ideal planting distance is 25 centimeters, which is why you should plan around ten plants per square meter of planting area. However, the spacing may vary depending on the variety selected.
Watering sunflowers
Water the sunflowers moderately but regularly - this promotes flowering. However, while the plants react quite insensitively to dry phases, they cannot tolerate waterlogging at all. If the dry periods last too long, the flowers wilt. Sunflowers really like hard water, which is why they like fresh tap water - but not ice cold! – may be used for watering.
Fertilize sunflowers properly
If you have planted the sun roses in a location with nutrient-rich soil and perhaps added compost into the planting substrate, fertilization is not necessary at first. However, you can fertilize if necessary, for example if the flowers are rather poor due to a likely lack of nutrients. However, potted plants and specimens planted on nutrient-poor substrates should be supplied with a liquid fertilizer for flowering plants approximately every four weeks between April and August.
Cut sunflowers correctly
During flowering, you should regularly clean out spent branches to suppress the formation of seeds and instead encourage the sun roses to continue to bloom. After the main flowering period - but no later than September - grab the scissors and cut the plants back heavily in preparation for winter. The clippings are very suitable for composting.
Propagation
During the summer months, sunflowers can easily be propagated by cuttings or planters, and older plants can also be easily divided in spring or autumn.
Sowing
If you do not cut off the withered shoots, seed-bearing capsule fruits will develop from them. You can harvest these in autumn and use them for sowing. Allow the seeds to dry for several days and store them in a cool, dry place in a tightly sealed container. However, the sunflowers obtained from them are not pure. And this is how you grow the young plants from seeds:
- Sow the seeds in shallow trays from March.
- These are filled with growing substrate and
- should be kept cool at five to ten degrees Celsius.
- Cover the seeds only very thinly with substrate.
- Keep this slightly moist at all times.
- Pick out as soon as the first cotyledons appear.
- Now care for the plants separately in small pots.
- The ideal temperature is now around 15 °C.
- From the end of May, the young plants can go outdoors.
Cuttings
Sunflowers can be propagated just as easily using cuttings. To do this, cut off five to six centimeter long, non-flowering and half-woody shoots in summer. Place them in a small pot filled with potting soil and moisten them slightly. Place a translucent plastic bag or a cut PET bottle over it to create a warm, humid climate that is ideal for root growth. Alternatively, the cuttings can also be rooted in a glass of water.
The young plants should be kept cool but frost-free over the winter and only planted outdoors the following spring.
Division
In spring and autumn, it is also possible to divide larger sunflower cushions. Proceed as follows:
- Dig a strong and he althy plant over a wide area.
- Cut them into several parts using a clean and sharp knife.
- Each part must have several shoots and buds.
- Plant the sections separately in a new location.
- Water them well.
Diseases and pests
Diseases and pests rarely occur on sun roses, only aphids can become a problem. However, they can be easily driven away by spreading nettle manure.
Tip
Basically, most varieties of sun rose are hardy. However, in regions with wet winters or generally severe frosts, it is necessary to provide the plants with light winter protection. Fir or spruce branches, for example, are suitable for this.
Species and varieties
There are around 175 different species of sunflower, with hybrids - the so-called garden sunflower (bot. Helianthemum x cultorum) - being used in the garden. While species such as the common sun rose (bot. Helianthemum nummularium) mainly bloom yellow, the cultivated forms are available in numerous colors. The most beautiful variants for the home garden include the following:
Common sunflower (Helianthemum nummularium): yellow-flowering, robust, up to 30 centimeters high
'Annabell': numerous pink, simple flowers'Rose Glory': distinctive dark pink, simple flowers
- Alpine sunflower (Helianthemum alpestre): yellow-flowering, robust, up to 15 centimeters high
- Garden sunflower (Helianthemum x cultorum): different colors and shapes
'Ben Fhada': bright yellow flowers with an orange center, cushion-forming, evergreen, growth height up to 20 centimeters
'Bronze Carpet': brown-orange flowers, ground-covering, clump-forming, growth height up to 15 centimeters
'Cerise Queen': bright purple-red, double flowers with a yellow center, wintergreen, growth height up to 20 centimeters
'Cheviot': apricot-colored flowers, filigree growth, wintergreen, cushion-forming
'Cornish Cream': vanilla yellow, delicate flowers with a strong yellow center, winter green, clump-forming
'Bulpfaff': deep red flowers with a pink edge and yellow center, clump-forming, growth height up to 15 centimeters
'Golden Queen': bright yellow flowers with an orange center, richly flowering, wintergreen, growth height up to 20 centimeters
'Lawrensons Pink': purple-pink, semi-double flowers with a yellow center, clump-forming, wintergreen, robust, growth height up to 20 centimeters
'Raspberry Ripples': two-tone pink and white flowers, wintergreen, cushion-forming, conspicuous
'Rubin': dark red, double flowers, wintergreen, growth height up to 20 centimeters
'Ruth': red-brown flowers, grey-green foliage, cushion-forming, wintergreen
'Snow Queen' / 'The Bride': bright white flowers with a yellow center, develops dense cushions, growth height of up to 25 centimeters'Sterntaler': deep yellow flowers, compact, strongly clump-forming growth, growth height of up to 15 centimeters
