Common name: Hollyhock
This cottage garden favourite, a native of China, is classified as a perennial but is generally treated as a biennial in the UK.
It is quite hardy and prefers well drained heavily manured soil.
Single or double 100-125mm (4"-5") diameter flowers appear from July to September.
These range in colour through shades of white, yellow, pink, scarlet, crimson and purple, and grow on sturdy stems that can attain a height of around 2 metres (6-7ft) and may require staking to ensure stability.
Because of their height they are well suited to giving height to the back of a herbaceous border or screening an unsightly feature/view.
In dry weather they should never be allowed to dry out.
The ground around the base of the plants should be well mulched with two inches of old manure and/or leaf-mould.
Pests & Diseases
Perennial varieties are susceptible to ‘rust’.
The first signs if this disease is small yellow or rusty spots which form on the under side of the lower leaves and penetrates tot the upper surface.
This rapidly extends,and the leaves become speckled all over with black and orange mould,then they shrivel and fall off.
There are no remedies of any real value to counteract the attack once it has is developed!
Routine spraying with a recommended fungicide can sometimes help to keep this problem at bay, or dusting with green sulphur immediately after the first symptoms appear.
If they terminally succumb to the disease all the infected plants should be burned.
As a precaution it would be prudent not to grow new Althaea plants in this area for a few year in the event that the soil has become contaminated with the rust spores!
If growing as an annual, sow seed in trays of seed compost and maintain a minimum temperature of 16°-18°C (61°-64°F)
Germination should take four or five days.
Prick out seedlings when large enough to handle into 70mm (3”) pots of potting compost, and place in cold frame to grow on until planting out time.
With perennials, watch out for signs of slug damage when the new growth emerges, and treat accordingly.
It is advisable to protect the young growth from late frost with cloches.
Apply a mulch of well-rotted manure and water freely during dry weather.
Plant out annuals 600mm (24") apart in a humus rich soil.
As with most tall herbaceous plants, hollyhocks will benefit from some kind of support, particularly in exposed situations.
As the flowers fade, cut back the flowering stems to approx 150mm (6") above ground level.
This will often encourage a second flush of flowers.
If growing as a perennial, sow seed in trays and place in cold frame to germinate.
Germination should take four or five days subject to the weather.
Alternatively; sow directly into a nursery bed.
When seedlings are large enough to handle pot up into 150mm (6”) pots and grow on in a cold frame until planting out time.
Plant out perennials 600mm (24") apart in a humus rich soil.
At the end of the season cut down the stems to within a few inches of the ground.