Hollyhocks give a border its unmistakable cottage-garden look: tall spires of flowers rising above lower plants, often beside a fence or wall. Starting them from seed is inexpensive, but the important detail is their flowering cycle. Many traditional hollyhocks behave as biennials, forming leaves in their first year and flowering the following summer.
There are varieties with different habits, including some short-lived perennials and annual selections, so read the packet before expecting flowers immediately. Your main jobs are to sow at a suitable time, avoid damaging young roots and reserve enough space for those full-height stems.
Choose the variety for your border
Hollyhocks belong to the genus Alcea. Single flowers generally provide better access to pollen for insects than densely doubled flowers. Both can make attractive displays.
Check the mature height. Some reach well over two metres in suitable conditions, which means they belong behind smaller flowers rather than in front of a narrow path.
Decide whether you want a mixed packet or a particular colour. Collected seed from garden hybrids may produce a mixture of shades rather than faithfully repeating a named cultivar.
Sow indoors in April or May
The Royal Horticultural Society recommends sowing hollyhocks under cover in spring, commonly April or May. Fill small pots or modules with peat-free seed compost, leaving enough space to water without washing soil over the edge.
Sow the seeds at their packet's recommended depth, usually under a light covering. Water gently. A propagator or warm position around 16–21°C encourages germination according to RHS guidance.
As seedlings appear, give them bright light and ventilation. A tray in a hot, dark corner may produce weak stretched stems that are difficult to move into larger pots.
Growing young hollyhocks in modules
When seedlings develop true leaves and begin filling their modules with roots, move them carefully into individual pots if necessary. Lift them with as much of the compost around their roots as possible.
Hollyhocks can develop substantial taproots. Avoid repeatedly disturbing older seedlings or leaving them potbound for months. The younger the plant when it reaches its intended position, the more easily it usually establishes.
Keep the compost moist rather than saturated. A seedling with two leaves needs different watering from a large plant in the open ground, so check moisture before watering.
Direct sowing in May or June
You can also plant seed directly into the final position in late spring or early summer. The RHS recommends outdoor sowing in May or June, where soil conditions allow.
Prepare a weed-free patch with a reasonably fine surface, water if dry, then sow at packet depth and mark the area. Don't mistake slow-emerging hollyhock seedlings for weeds during your next tidy-up.
Thin seedlings so the developing plants have room. If you intend to transplant some self-sown plants elsewhere, move them while still young rather than waiting until their roots are deeply established.
Choose a sunny sheltered position
Hollyhocks flower best in full sun in a fertile, well-drained bed. Their impressive tall stems can catch the wind, so a wall, fence or sheltered boundary is useful.
Don't squeeze them directly into a narrow gap between a path and a wall, where roots have little room and the lower leaves remain damp. Leave space to inspect foliage and attach stakes if needed.
The RHS suggests planting established hollyhocks around 60cm apart. Allow for that spacing when thinning seedlings or setting out young plants. A dense row may look full quickly but can become congested.
Prepare the planting hole
Remove weeds and loosen the soil before taking the plant out of its pot. Add well-rotted compost where the bed needs organic matter, but avoid burying the crown in a mound of wet material.
Dig a hole wide enough for the rootball. Water the young plant if its compost is dry, then slide it out gently without pulling its leaves.
Set it at roughly its nursery depth, backfill and firm gently. Water in well so the rootball and surrounding soil make good contact.
Give seedlings time to establish
For the first few months, keep the soil moist enough to support new roots. RHS guidance says to ensure the top 15cm of soil is damp rather than soggy while young plants establish.
A mature hollyhock may need water mainly during prolonged dry spells, but a new plant with a small rootball cannot draw moisture from as wide an area.
Mulch suitably with organic matter if it helps conserve moisture and suppress weeds. Leave the immediate crown clear rather than burying it under a thick damp layer.
Protect from slugs and snails
Young hollyhocks can lose leaves very quickly to slugs. Inspect the seedlings after wet evenings and remove pests or use suitable measures as needed.
If the seedling's centre is repeatedly eaten, it may not have enough energy to recover properly. Protect small plants promptly instead of waiting for severe damage.
Once plants become taller and tougher, the main concern often changes from being eaten to disease on the foliage, particularly hollyhock rust.
Support tall flower spikes
As plants send up flowering stems, add sturdy canes or other suitable stakes if your site is windy. Position them carefully so they do not damage the roots and use loose soft ties.
Check support after heavy wind and rain. A flower spike that has bent sharply may not recover its original shape, so prevention is easier than repair.
Support should not strangle thickening stems. Inspect ties during the season and loosen them when necessary.
Understand hollyhock rust
Hollyhock rust is a common fungal disease that produces rust-coloured pustules and spotting, often starting on older lower leaves. It can make plants look untidy long before flowering ends.
Remove heavily infected leaves where practical and avoid allowing diseased debris to build up. Don't compost infected leaves if your composting process is unlikely to destroy the disease reliably.
Airflow and replacing exhausted older plants with younger ones can help. The RHS notes that older hollyhocks are particularly vulnerable and recommends refreshing plantings regularly.
When will the flowers appear?
Many traditional biennial hollyhocks bloom in their second summer. In the first growing season, a rosette of leaves may be perfectly normal. That isn't evidence that the seed packet has failed.
Some varieties and favourable sowing conditions lead to earlier flowers, but always check the characteristics of the seed you've bought rather than making promises about first-year displays.
In the flowering year, flowers generally open successively along the spike. Deadheading after the display helps tidy the border, while leaving selected seedheads allows seed collection.
Saving seed and managing self-sown plants
Let selected flower spikes form mature dry seedheads. Collect them in a dry spell, separate the seeds carefully and keep them in a labelled paper packet in suitable cool, dry storage.
Allowing some seed to fall naturally can maintain a loose collection of hollyhocks in a cottage border. New plants may emerge several feet away from the original.
Move self-sown seedlings while young if they appear in a path or an overcrowded position. A mature established hollyhock is less forgiving of root disturbance.
Common mistakes to avoid
Expecting flowers immediately from a traditional biennial is the first mistake. The second is planting tall varieties in exposed ground without considering stakes.
A third is allowing plants to remain densely packed and rust-infected for years. Keep a succession of younger plants and give them space for light and air.
Hollyhocks reward patience. Sow in spring, establish them carefully and let the first year's foliage prepare for the tall flowering spikes that follow.