Flowering time (month)
Ornamental or utility value
nectar or pollen plant
dry to moderately moist
Stock-roses (Alcea) form an independent type with approximately 60 types within the family of the Malvengewächse (Malvaceae). They originate from the eastern Mediterranean and have been native to Europe and Asia for some time, where they were used as useful plants for medicinal purposes and for colouring food. The common hollyhock rose (Alcea rosea), also known as hollyhock or peasant rose, is the most popular representative and is often used as an ornamental plant in the garden. Already in ancient Rome mallow plants were known as medicinal plants. There the hollyhock rose got the Latin name Alcea. Later, the Greek name Althea (= heal) was also used in the botanical nomenclature, which is why the hollyhock rose is still sometimes traded under this name today.
Characteristic for the hollyhock is its high growth of up to two meters. The hollyhock is biennial, i.e. in the first year only the rosette of leaves is formed, in the second a long, straight stem grows from it. On it, ears of corn form with conspicuous, large flowers in many beautiful colours. The stem of the hollyhock is not very branched and strong and grows straight up to the top. The entire plant is covered with slightly prickly hair.
The multi-lobed, light green leaves of the hollyhock spring from a basal rosette. The leaves grow up to 16 centimetres and are slightly hairy. They sit on also hairy stems. In the second year, alternate stem leaves also grow on the flower stem.
The strong, palm-sized flowers of the hollyhock appear from July to September. They are available both filled and unfilled in a wide range of colours from white, yellow, apricot, pink or red to violet and purple black. Tip: Single flowering varieties are considered more persistent than stuffed roses.
Location and soil
Stock roses like a nutrient-rich, permeable and dry to slightly moist soil. They like to stand in full sun. The best location for your hollyhock is a sunny bed with a permeable soil. Stocks that are too densely sown or planted should be thinned out in good time so that the individual plants can develop more vigorously. The leaves also dry better and are less susceptible to mallow rust.
Planting and care
Stock roses are actually perennial plants. However, as they are very exhausted during flowering, the splendour of the flowers diminishes considerably from year to year. It is therefore better to cut back some of the flowering plants and ensure a constant rejuvenation by sowing. The mallows are sown either in autumn or from June directly into the bed. If you plant early young plants in early autumn, the mallow can still develop well before flowering next year. Plant stock mallows with enough space between the plants so that the leaves can dry quickly after a downpour. In the following spring the hollyhock gets a good compost fertilization. In summer, the fast-growing plants need plenty of water. To prevent the soil from drying out so quickly, a protective mulch layer is advisable. Support the long stems in unprotected locations with a sturdy rod, as roses can easily bend in the wind.
Stick roses can also be preferred in growing trays. The seed in the loosened substrate is thinly covered with soil (dark bucket!) and watered. After two to three weeks the first seedlings appear, which then have to be isolated. In the first season, the young plants only form leaves. Next spring they start with well developed rosettes and then show their flowering splendour throughout the summer. Tip: Don’t wait too long before isolating and later planting out, as hollyhock roses like to root deep and quickly become too narrow in the flat growing trays.
A pruning after withering prevents unwanted self sowing and prolongs the flowering time. Tip: Two-year-olds normally die after semen ripening. If the plants are shortened immediately after withering, this often leads to a renewal of the leaf rosette and a further flowering in the following year.
Stock roses are biennial and do not normally require winter protection. The above-ground part of the plant dies in winter and can be cut off. Next spring the plant will sprout again. If you want to be on the safe side, you can cover the hollyhock with leaves or brushwood during frost.
The hollyhock rose is a popular farmer’s garden plant and therefore also bears the name farmer’s rose. Since it is in need of leaning against, it is suitable for the shrub bed as location only with sufficient support. Stock roses, on the other hand, have a great effect in front of bright house walls, walls or along fences and as an attractive background for herbaceous and flower beds. Planted in groups, they are also effective in borders and provide colour spots at lofty heights. Tip: Mix black flowering and pastel varieties.
In romantic country house gardens, hollyhock roses with their enduring blossoms accompany larkspur, sunflowers, phlox and roses. The long flower panicles of the hollyhock also look good as cut flowers. To prolong the flowering period in the vase, the leaves of the stem are removed and the end of the stem is immersed in boiling water for 40 seconds.
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Polarstern’ (white with yellow eye) and ‘Mars Magic’ (red) belong to the single flowering, long-lasting Spotlight series. The hollyhock rose ‘Nigra’ blooms from dark purple to almost black. Fine colour nuances from cream white to apricot, on the other hand, characterise the flowers of the stock rose variety ‘Champagne’. It is also suitable for pots and is about 1.70 meters high. The red violet, double flowers of the hollyhock rose ‘Cassis Swirl’ remind a little of English roses.
Tip: More durable than the common hollyhock is the cross of hollyhock (Alcea rosea) and marshmallow (Althaea officinalis) of the Hungarian breeder Kovats. These so-called Bastardmalven (x Alcalthaea suffrutescens) include the well-known varieties ‘Parkallee’ (light yellow, semi-double), ‘Parkfrieden’ (light pink) and ‘Parkrondell’ (dark pink, semi-double). Their flowers are slightly smaller than the usual hollyhock roses, but the plants are more stable and less susceptible to mallow rust. Attention: These hybrids are not available as seeds, but only as potted young plants.
Stick roses like to sow themselves. In order to encourage self-seeding, you should leave the seeds over the winter and only remove them next spring. Alternatively you can collect the seeds and spread them selectively. A sure sign for ripe stock rose seeds are dry capsules, which can already be opened or effortlessly pressed on. The individual seeds are very small, brown in colour and easy to release. If sown immediately after collection in August or September, the hollyhocks form a strong rosette next year and flower in the following year. Depending on the region, weather, seeds and some other factors, the seeds may germinate in autumn and flower next year. Alternatively, you can take your time until late spring or early summer and sow directly into the prepared bed.
Diseases and pests
The main disease of hollyhock roses is mallow rust (Puccinia malvacearum), which occurs so often that it almost belongs to hollyhock roses. It mainly attacks the leaves and is recognizable by yellowish spots and reddish-brown pustules (spore deposits) on the undersides of the leaves. The roses become increasingly barren, even if the plants continue to flower.
If infested, continuously remove the infected leaves and dispose of them with your household waste. A fungicide (for example rose spray Saprol F, Muszfrei Ortiva or Pflanzen Paral Musz-Frei N) stops the further spread. In autumn the plant should be completely pruned back and piled up with soil. Also remove this soil and the first new leaf shoots in spring. In order to prevent mallow rust infestation, the hollyhock roses should be planted at a suitable, airy location and never watered over the leaves.
I am Don Burke, one of the authors at My Garden Guide. I am a horticulturist that cultivates, grows, and cares for plants, ranging from shrubs and fruits to flowers. I do it in my own garden and in my nursery. I show you how to take care of your garden and how to perform garden landscaping in an easy way, step by step.I am originally from Sydney and I wrote in local magazines. Later on, I have decided, more than two decades ago, to create my own blog. My area of specialization is related to orchid care, succulent care, and the study of the substrate and the soil. Therefore, you will see many articles dedicated to these disciplines. I also provide advice about how to improve the landscape design of your garden.