When to Plant Marshmallow in Canberra, Cold / Highland Guide
Soil temperature is modelled from Open-Meteo forecast (Canberra), not a live sensor.
What this month normally looks like in Cold / Highland
In October the Cold / Highland zone normally runs 20°C by day and 7°C overnight, with about 58 mm of rain over 7 or 8 wet days. The coldest October night on record across the zone was -6.4°C, so a late frost is not out of the question. Averages 1991 to 2026, 15 postcodes, SILO.
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This Marshmallow guide is written for the Cold / Highland zone, which takes in Canberra, Cooma and Bright. Somewhere else? Your postcode picks the right one.
Not your zone? Cairns Brisbane Sydney Melbourne Alice Springs Perth
Also handy: will it frost this week? and what grows in shade.
- Planting window
- Sep to Dec
- Days to harvest
- about 104 weeks
- Sun
- Full sun to part shade
- Soil pH
- 6.0–7.5
Marshmallow is a tall, upright, soft-leaved perennial herb to about 1.2m with pale pink-white flowers. The leaves, flowers and roots are used in herbal teas and traditional remedies, and it prefers moist, sunny sites.
Published · By GardenBuddy.au
Planting dates, current conditions and prices on this page update daily.
Photo: Wikimedia Commons
Planting Calendar for Cold / Highland
- Jan -
- Feb -
- Mar -
- Apr -
- May -
- Jun -
- Jul -
- Aug -
- Sep S
- Oct S/T/D
- Nov S/T/D
- Dec T
S = Seed Tray T = Transplant D = Direct Sow
Want a nudge when it is sowing time?
One email a week with what is worth planting in the Cold / Highland zone right now, Marshmallow included, plus which veg has jumped in price at the supermarket. Free, and you can stop it in one click.
How to Grow Marshmallow in Cold / Highland Australia
- Soil
- Moist, rich, organic loam or damp marshy soil
- Salt
- Moderately sensitive. Copes with a little salt, but the harvest drops on salty bore water.
- pH Range
- 6.0-7.5
- Sunlight
- Full sun to partial shade, at least 4 to 6 hours of direct sun a day
- Spacing
- 46-80cm apart, 50cm between rows
- Watering
- keep soil very moist but not submerged; water at soil level to keep foliage dry
- Good companions
- Comfrey, Borage, Lavender, Chamomile, Calendula
Cold / Highland Growing Tips for Marshmallow
Key Challenges
- Hollyhock rust: Badly affected leaves shrivel and drop and plants become stunted
- Aphids: Sap-sucking, virus transmission
- Two-Spotted Mite: Reduces plant vigour
- Harlequin Bug: Sap sucking causes wilting and distorted growth
Pro Tips
- Incorporate well-rotted organic compost prior to planting; top-dress with compost or balanced organic fertiliser each spring
- Apply a thick organic straw mulch around the base to preserve root zone moisture and suppress weeds
- Cut dead stems back to ground level in late autumn after foliage dies down following early winter frosts
Pests and problems for Marshmallow in Cold / Highland
- Aphids Aphids: Sap-sucking, virus transmission Watch
- Hollyhock rust Space plants for good air flow, water the soil instead of the leaves, control weedy mallows nearby, and do not save seed from infected... Watch
- Two-Spotted Mite Two-Spotted Mite: Reduces plant vigour Watch
- Harlequin Bug Harlequin Bug: Sap sucking causes wilting and distorted growth Watch
Harvesting Marshmallow
When ready: Harvest leaves and flowers during mid-summer flowering; harvest mucilaginous roots in late autumn of the second year when stems die back
How to harvest: Snip leaves with sharp scissors; dig deep thick roots carefully with a garden fork in autumn
What members get
- Soil and weather from your nearest station
- An email when it's time to sow
- Your own garden plan, including planning from a photo
- Price history and price alerts
- Pest risk alerts for your area
- Full salt and canning detail
Common Questions About Marshmallow
When do you plant marshmallow in Australia?
It depends on your climate zone, not the calendar month alone. Planting months by zone:
- Tropical (Cairns): Apr to Aug
- Subtropical (Brisbane): Mar to Jun, Sep to Dec
- Warm Temperate (Sydney): Mar to Jun, Sep to Dec
- Cool Temperate (Melbourne): Mar to Apr, Sep to Dec
- Cold / Highland (Canberra): Sep to Dec
- Arid / Semi-Arid (Alice Springs): Mar to Jun, Sep to Dec
- Mediterranean (Perth): Mar to Jun, Sep to Dec
Can you grow marshmallow all year round in Canberra?
No. In the Cold / Highland zone the planting months are Sep to Dec. Outside that window it either bolts, sulks or gets cut down by the weather.
When should I plant Marshmallow in Canberra?
Sow direct in spring after heavy frosts pass into rich moist soil; plants go dormant in winter and re-emerge in spring.
What soil temperature do Marshmallow need?
Marshmallow germinate best when soil temperature is between 18°C and 24°C.
How do I know when Marshmallow are ready to harvest?
Harvest leaves and flowers during mid-summer flowering; harvest mucilaginous roots in late autumn of the second year when stems die back
What grows well with Marshmallow?
Good companion plants for Marshmallow include: Comfrey, Borage, Lavender, Chamomile, Calendula.
Are marshmallow salt tolerant?
Only a little. Marshmallow are moderately sensitive to salt, so the harvest drops on salty bore water. Mix salty water with rainwater, and mulch the bed.
Which zone am I in?
Type your postcode into the box near the top of the page and it tells you, and links this crop in your own zone if it differs. Or look it up on the grow zone map. This page is the Cold / Highland zone, Canberra is its reference city.