How to Grow Hollyhock
'Blackberry' from Seed
Two-metre spires of deep wine-purple flowers that read as near-black in shade. A hollyhock dark enough to stop people on the path.
'Blackberry' is a hollyhock for drama. The flowers open a deep wine-purple and darken further as they age, looking almost black in shade and showing their true colour only when the sun shines straight through them.
It grows to around two metres in reasonable soil and wants a place at the back of a border with something solid behind it. Against limewash, pale brick or weathered wood, those dark spires look spectacular, and well worth the wait from summer sowing to flowering the following year.
Quick Facts at a Glance
Plant Type
Hardy biennial
Sowing Time
May to July
Flowering
June to August, the following year
Position
Full sun, pale background
Height
Around 2m
Difficulty
2 out of 5, easy
Understanding the Plant
'Blackberry' is a variety of Alcea rosea. Like all hollyhocks it is a biennial, making leafy rosettes in its first year and flowering spires in its second. It often lives on for a third season.
Hollyhocks root deeply, so they settle best when planted out young and left in place. Once established, they are tough plants that handle dry summers well.
Give dark flowers a light background
Very dark flowers vanish against a hedge or dark fence. Plant 'Blackberry' where the spires will be seen against a pale wall, light stone or the sky, and the colour will glow when the sun catches it.
When & How to Sow
Sow from May to July, grow the plants on through summer and plant them out in autumn to flower next year.
Deep pots for deep roots
Use deep modules or 9cm pots and plant out before roots start circling. Hollyhocks that sit too long in small pots are slow to establish.
Sow 1cm deep. Sow one or two seeds per deep module or pot, or in a nursery row outdoors. Seedlings appear in one to three weeks.
Grow on through summer. Water regularly and pot on if roots fill the pots before autumn.
Plant out in autumn. Plant in September or October, 45 to 60cm apart, in full sun at the back of the border.
Growing On Tips
Full sun
More sun means sturdier spires and lets the dark colour show at its best.
Stake in the wind
A two-metre spire carrying wet flowers is heavy. In exposed gardens, tie it to a strong cane.
Choose the backdrop
Limewash, pale brick or silvered timber make the dark flowers stand out.
Watch for rust
Remove rust-spotted leaves promptly and clear old foliage in autumn.
Bees
Bees visit hollyhocks throughout their flowering season.
Self-seeding
Leave a spire or two to set seed for future plants.
Common Problems & How to Fix Them
| Problem | Likely Cause | What to Do |
|---|---|---|
| Orange spots under leaves | Hollyhock rust | Remove affected leaves, clear debris in autumn and space plants for airflow. |
| No flowers in the first year | Normal for a biennial | Flowering comes in the second summer. Sow every year for a continuous display. |
| Spires snapped or leaning | Wind, heavy wet flowers | Stake early in exposed gardens. |
| Flowers disappear visually | Dark background | Move future plantings in front of a lighter wall or fence. |
| Young leaves eaten | Slugs and snails | Protect young plants after autumn planting. |
When to Expect Flowers
Plants sown this summer and planted out in autumn flower from June next year, through July and into August.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 🌱 Sow (year 1) | ||||||||||||
| 🪴 Plant out (year 1) | ||||||||||||
| 🌸 Flowering (year 2) |
Plant Specifications
Near-black spires for the back of the border
Sow in summer, plant out in autumn against a pale backdrop, and next year you will have dark, dramatic hollyhocks that glow in the sun.
Shop Hollyhock Blackberry Seeds →