When to plant Hollyhock in Temperate Australia
Temperate zone — applies to Sydney, Melbourne, Adelaide, Perth, Newcastle and similar areas. Growing elsewhere? Cool · Subtropical · Tropical · Arid.
Raise hollyhock seedlings and transplant them out, sowing from February to May so the biennial plants establish over winter and throw up their tall flower spires the following summer. Set the seed 8 mm deep; it germinates in 6 to 20 days, and plants take 200 to 220 days to reach flowering. Space transplants 30 to 50 cm apart with rows 45 to 60 cm wide, giving the towering stems room. Hardy and cottage-classic, hollyhocks (Alcea rosea) suit sunny fence lines and back-of-border positions in Melbourne, Adelaide and Newcastle gardens.
Sowing calendar — temperate zone
Green months are your sowing window: February to May.
Growing notes
Hollyhocks are grown as biennials or short-lived perennials in temperate gardens. An autumn sowing builds a strong rosette over winter and flowers in the following summer, sending spikes up to two metres or more. They want full sun, deep rich soil and shelter from strong wind, which snaps the tall stems. Because they resent root disturbance once established, raise seedlings in deep cells and transplant while young.
The defining failure mode here is hollyhock rust. This fungal disease shows as orange pustules on the undersides of the leaves and can strip a plant to bare stems by flowering time, and it is near-universal in humid coastal temperate gardens around Sydney and Melbourne. Manage it by spacing plants for airflow, watering at the base rather than over the leaves, removing and binning affected lower leaves as they appear, and clearing all old foliage at season's end so spores do not overwinter. Choosing a sunny, open, breezy spot makes a real difference.
Stake or site the spikes against a fence early, before they get top-heavy, as a summer storm will flatten unsupported plants. Leave a few spent spikes to self-seed if you want a self-renewing patch, since individual plants are short-lived.
Hollyhock at a glance
| Sowing depth | 8 mm |
|---|---|
| Plant spacing | 30-50 cm |
| Row spacing | 45-60 cm |
| Germination | 6-20 days |
| Days to maturity | 200-220 days |
| Frost tolerance | Hardy |
| Method | Plant Seedlings |
Common questions
- when do you plant hollyhock seeds in Australia
- In temperate zones sow from February to May, raising seedlings to transplant out. As biennials they establish over winter and flower the following summer, taking 200 to 220 days to bloom.
- how do I stop rust on my hollyhocks
- Hollyhock rust is very common in humid coastal gardens. Space plants for airflow, water at the base rather than over the leaves, remove affected lower leaves promptly, and clear all old foliage at the end of the season so spores do not carry over.
- do hollyhocks flower in their first year
- Usually not. Grown as biennials from an autumn sowing, they form a rosette in the first season and send up their flower spikes the following summer. Some may behave as short-lived perennials and return for a few years.
- how tall do hollyhocks grow and do they need staking
- The flower spikes commonly reach two metres or more. In an exposed spot they need staking or a fence to lean on, put in early before they become top-heavy, or a summer storm will flatten them.
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