When do you plant hollyhocks? How can you propagate hollyhocks from seeds and what should you consider when cutting? The best varieties and tips for caring for hollyhocks.
In the middle of summer, the bee-friendly and towering hollyhocks bloom in many bright colors and adorn our balconies, house walls or garden fences with their large flowers. Contrary to what its name suggests, the hollyhock does not belong to the rose family (Rosaceae) and also has major optical differences to the species of the genus Rosa. If you want to learn about planting, caring for and the diversity of varieties of roses, you will find it in our special article about this flower queen.
Hollyhocks: flowering time, origin and properties
Hollyhocks (Alcea) are flowering perennials and form their own genus in the mallow family (Malvaceae). The old garden mallows originally come from the Orient. They have also felt at home in Europe for a long time. Their special feature is their height. Hollyhocks can grow up to 3 m high and are often planted at the back of perennial beds or on house walls. This is how they come into their own.
Hollyhocks are usually biennial, but in favorable locations they can also be perennial. If they are re-seeded every year, you can admire their beautiful flowers year after year. In the first year, only the rosette of leaves is formed, from which a strong, barely branched stalk with numerous spikes of flowers grows in the second year. The stem and the lobed, about 15 cm large leaves of the hollyhocks are light green in color and have rough hairs. The flowering period of hollyhocks lasts from July to September. There is a large variety of hollyhock species and varieties, the flowers of which appear in many different colors and can be single or double. Probably the most well-known and widespread type of hollyhock is the common hollyhock (Alcea rosea). It is also called peasant rose, hollyhock or garden mallow.
Tip: The hollyhock species Alcea rosea and Alcea ficifolia are more biennial than perennial. On the other hand, Ficifolia hybrids of Alcea ficifolia and Alcea rosea (Alcea x ficifolia) tend to be more than biennial.
Hollyhock Varieties
Popular varieties of common hollyhock are Alcea rosea 'Nigra' with deep red, almost black flowers and Alcea rosea 'Pleniflora', which is available in many bright colors such as yellow, dark pink or red and whose flowers are bulging. Both varieties grow to a height of around 2 to 2.5 m.
A less well-known species of hollyhock is the hollyhock (Alcea pallida), also called Balkan hollyhock. It grows to a height of 1.8 to 2.5 m and has up to 10 cm large, wonderfully fragrant pastel pink flowers. Its flowering period lasts from May to October and is therefore extremely long. The pale hollyhock is very easy to care for and resistant to drought and mallow rust.
The varieties 'Mars Magic' and 'Polarstar' from the Alcea rosea Spotlight series stay a little lower. They reach a height of 1.6 to 1.8 m and form large cup-shaped flowers in fiery red or white with a yellow center. They have a special long-distance effect in perennial beds.
Tip: The flowers of the double hollyhocks are less bee-friendly than the single flowers.
Plant hollyhocks
Hollyhocks can either be bought as young plants in gardening shops and then planted directly in the desired spot in the garden, or you can sow them. In addition to the right sowing time, the choice of location plays an important role in the development of perennials.
When do you plant hollyhocks?
The sowing of the hollyhock seeds can start in May or June. Hollyhocks can also be sown into autumn. The planting of early hollyhocks from the trade can also be carried out from May. If the hollyhocks have been sown densely in a bed, they should be transplanted to their intended spot in the garden or perennial bed before the start of winter so that they can develop well in the following spring.
What is the perfect location for hollyhocks?
Hollyhocks do well in warm, sunny locations in the garden or on the balcony. They prefer a nutrient-rich and permeable, dry soilto moderately moist soil. If the soil in your garden does not meet these requirements, it is advisable to use high-quality potting soil, such as our Plantura organic potting soil. The location should also be as sheltered as possible from the wind, as the stems of the hollyhocks can easily break in the wind due to their height. Hollyhocks exposed to wind must be tied to a wooden stick or similar in good time to prevent damage.
How to plant hollyhocks in the bed
Hollyhock seeds can be sown in a loose, finely crumbly seedbed in the garden from May until late summer. For better germination success on very sandy or very heavy garden soil, the upper layer of soil should be mixed with a seed compost such as our Plantura Organic Herb & Seed Soil. Then place 2 to 3 seeds at a time in small hollows at a distance of 5 to 10 cm. Since hollyhocks germinate in the dark, the seeds must be covered with a substrate layer about 2 cm thick. The seeds germinate within 2 to 3 weeks and gradually develop into strong young plants. Now they have to be carefully dug up and planted in the designated place in the garden. Make sure that there is sufficient planting distance of 50 to 60 cm between the individual hollyhocks. In the first year, only a rosette of leaves forms on the young plants, from which a stalk with numerous flowers grows in the second year.
Tip: As an alternative to growing the young plants on a seedbed, the seeds can also be sown directly in the flowerbed.
Planting hollyhocks in tubs
Hollyhocks can also be kept in pots on the balcony or terrace. Due to its slender, tall growth, the hollyhock is very space-saving and therefore particularly well suited for smaller balconies. Hollyhocks develop taproots, which is why you should pay attention to a sufficient height when choosing a suitable planter. In addition, the bucket must have a drainage hole, as waterlogging is to be avoided. Fill it with a suitable substrate such as our Plantura organic potting soil. Some sand can be added to increase the permeability of the substrate. Then, as described above, 2 to 3 seeds are placed in small wells about 50 cm apartlaid flat and covered with substrate.
Hollyhock Care
Hollyhocks are easy to care for and apart from regular watering, occasional fertilizer and pruning in autumn, they do not require any special care. In windy locations, tying to a wooden stick may be necessary to protect the stem from wind damage.
Pruning Hollyhocks
When the hollyhocks have faded, the stems should be cut back to about 10 cm above the ground. If you cut back immediately after flowering, this can even lead to another flowering in the following year. However, if you are pursuing the goal of seed production, you may only cut the hollyhocks after the seeds have ripened.
Fertilize and water hollyhocks
Particularly in the first few weeks after sowing, it is important that the soil moisture is as constant as possible so that the seeds can germinate successfully. Young plants should also be watered regularly so that they can develop well. In summer, the soil around the hollyhocks must be kept at least minimally moist. By covering the soil with a light layer of mulch, you can keep the moisture in the soil longer.
In the second year, the hollyhocks also look forward to spring fertilization. Our Plantura organic flower fertilizer, for example, is very suitable for this. Alternatively, nutrient-rich organic compost can also be used.
Propagating Hollyhocks
Hollyhocks multiply all by themselves if you wait until after the seeds have ripened to cut back the stems. The mature seeds fall to the ground and, under favorable conditions, will germinate the same year or the following year and grow into new hollyhocks.
Sowing Hollyhocks: Propagation by Seeds
If you want to control the propagation better, you can harvest the ripe, brown seeds in late summer and then sow them in autumn or early summer as described above. If the seeds are not going to be sown immediately, it is important to dry them first and then store them in a dark container. This jar should not be airtight or mold may develop.
Tip: Hollyhock seeds are often damaged by the long-nosed hollyhock shrew (a weevil). It bores holes in unopened flower buds and lays eggs in them. The seeds then contain larvae and are deaf, so unusable. Therefore, you should definitely check the seeds for holes before storing themcheck.
Winter hollyhocks: Are hollyhocks hardy?
The two-year-old hollyhocks are hardy and do not need winter protection here. The above-ground plant parts of the hollyhocks die off after flowering in the cold season and can be cut back. At very low temperatures, you can put a layer of leaves or fir branches over the hollyhocks to protect them from frost. This measure is particularly advisable for young plants.
Hollyhock diseases and pests
Mallows that are too close together are very often attacked by a hollyhock disease called mallow rust. Mainly the hollyhock leaves are affected. You can recognize the fungal attack by yellow spots and rust-red pustules on the leaf surfaces. As soon as an infested leaf is sighted, it should be removed from the plant immediately and disposed of with the general waste to prevent further spread.
Another fungal disease in hollyhocks is wilt disease (Phoma). When infested by the corresponding fungus, the hollyhocks begin to wither from below. The oldest leaves are attacked first and turn brown at the leaf edges. The discoloration increases towards the middle and the affected areas turn black. Since these spots contain fungal spores that can spread to other plants, you should immediately dig up the plants completely and dispose of them with the residual waste and replace the soil around the plants.
The following pests cause damage to hollyhocks:
- Hollyhock shrew (Rhopalapion longirostre): The weevil burrows holes in the flower buds and lays eggs inside; the seeds later contain larvae and are useless.
- Mallow flea beetle (Podagrica fuscicornis): The beetle often appears when the soil is too dry and bores holes, especially in the stems of hollyhocks; it lays its eggs in these holes, from which larvae hatch, which then eat plant tissue and thereby damage the plant.
- Especially in spring, aphids (Aphidina) and slugs, which suck the sap from the hollyhocks or damage them by feeding, appear more frequently.
If you're interested in other bee-friendly plant species for your perennial border, check out our special article on bee-friendly perennials for more inspirationfind.