Stokroos

Alcea rosea

Engels: Hollyhock

perennialMalvaceae

Stokroos (Alcea rosea) is a perennial from the Malvaceae family that grows up to 250cm tall. This plant thrives in full sun and requires moderate maintenance. Blooms in summer and late summer with pink, red, yellow, white, purple flowers and attracts bees and butterflies.

Hoogte

150–250 cm

Breedte

30–60 cm

Zonligging

full sun

Waterbehoefte

moderate

Grondsoort

loam, chalky soil, sandy soil

Onderhoud

moderate maintenance

Bloeitijd

summer, late summer

Bloemkleuren

pink, red, yellow, white, purple

Ecologische waarde

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Verzorgingskalender

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Care tips

Planting

Hollyhocks thrive in full sun and tolerate a wide range of soils, including loam, chalky, and sandy types, provided drainage is reasonable. They perform best in a sheltered spot out of strong winds, as their tall flower spikes can snap easily. Choose a position at the back of a border or against a wall or fence where they can provide height and structure. Prepare the soil by digging in well-rotted compost or manure to improve fertility and moisture retention, especially on sandy soils. Hollyhocks develop long taproots, so deep soil preparation is important. If your soil is heavy clay, work in grit or sharp sand to improve drainage. Plant young hollyhocks in May, June, or September, spacing them 45 cm apart to allow good air circulation—this helps reduce the risk of rust, a common problem. Dig a hole slightly larger than the root ball, set the plant at the same depth it was growing in its pot, and firm the soil gently around the roots. Water thoroughly after planting to settle the soil and eliminate air pockets. If you're sowing seed directly outdoors, do so in late spring or early summer in a prepared seedbed, covering lightly with soil. Thin seedlings to 45 cm apart once they're large enough to handle. Alternatively, sow in pots in a cold frame and transplant in autumn or the following spring. After planting, water regularly until plants are established. Apply a 5 cm layer of organic mulch around the base to conserve moisture and suppress weeds. In exposed sites, consider staking tall stems early to prevent wind damage.

Pruning

Hollyhocks don't require complex pruning, but timely attention in autumn keeps plants tidy and can encourage longevity. The main pruning window is October and November, after flowering has finished and before winter sets in. Once the flower spikes have faded and seed pods have formed, decide whether you want self-sown seedlings. If you're happy for hollyhocks to spread naturally around the garden, leave some spent spikes intact so seed can scatter. If not, cut the entire flowering stem down to the basal rosette of leaves at ground level using secateurs or loppers. Remove all spent stems and dispose of them, especially if rust disease has been present, to reduce overwintering spores. In late autumn, tidy the basal foliage by removing any yellowing, damaged, or rust-infected leaves. Don't cut back healthy green rosettes—these will overwinter and fuel next year's growth. If rust has been severe, remove all affected foliage and bin it (don't compost), then clear away any leaf debris around the base. During the growing season, deadhead individual flowers as they fade if you want to prolong blooming slightly and keep plants looking neat, though this won't significantly extend the main flowering period. Snap or cut off spent blooms just behind the flower head. Hollyhocks are often short-lived perennials or biennials, so don't be surprised if plants decline after two or three years. Allowing some self-seeding is the easiest way to maintain a continuous display without replanting.

Maintenance

Water hollyhocks regularly during dry spells in spring and summer, especially while flower spikes are developing. Aim for deep watering once or twice a week rather than frequent shallow sprinkles, as this encourages strong root growth. Once established, they tolerate moderate drought but flower better with consistent moisture. Reduce watering in autumn and winter when plants are dormant. Feed in April and May to support vigorous growth and abundant flowering. Apply a general-purpose granular fertiliser such as blood, fish and bone around the base of each plant, or use a balanced liquid feed every fortnight during the growing season. Avoid high-nitrogen feeds, which promote leafy growth at the expense of flowers. Hollyhocks are fully hardy across temperate Europe and need no special winter protection. The basal rosette of leaves will persist through winter and resprout in spring. A light mulch of compost or well-rotted manure applied in late autumn helps insulate roots and adds organic matter. Rust is the most common problem—orange-brown pustules appear on leaves, often starting at the base and spreading upwards. Remove affected leaves promptly and ensure good spacing and air circulation to minimise spread. Avoid overhead watering, which encourages fungal diseases. In severe cases, apply a fungicide labelled for rust, though prevention through good hygiene is more effective. Aphids occasionally cluster on young shoots and flower buds; squash by hand or spray with soapy water. Slugs and snails may damage emerging shoots in spring, so use organic pellets or barriers if necessary. Mulch annually to suppress weeds and retain moisture.