May is the last month of autumn, when the weather starts cooling down, but there are still sunny days. There are frosts inland and in the high regions. Cold windy days are expected in the southern states, and weather in Hobart is cool and rainy. Snow is a possibility in the ranges around Canberra, the Snowy Mountains and Victorian Alps.
This is a time for pruning, taking cuttings for propagation, dividing perennials, and planting new trees, shrubs and vines. The soil is still warm enough for moving and relocating plants around the garden.
It’s also the time to clean up the garden, to remove all the dead and dried leaves, branches and plants, which is a great source of organic matter for mulching and composting!
Things to Do This Month:
- Continue planting new trees, shrubs, climbers, annuals and perennials.
- Continue gathering and composting autumn leaves.
- Continue planting cool season green manure crops (such as rapeseed, broad beans, fenugreek, linseed, lupins, mustard, oats, subclover, and vetch), which will be cut down and dug into the soil in spring.
- Continue collecting and sowing seeds from berry producing trees and shrubs.
- Continue lifting and dividing overgrown perennial plants.
- Continue planting garlic.
- Continue pruning brambleberries after they finish fruiting – cut out the canes that have fruited, and tie in the newly grown canes to the support wires on the berry trellises.
- Winter pruning of deciduous trees and shrubs can be done in autumn or winter, and can begin now.
- Check citrus for galls caused by gall wasp and slice one side of galls or prune to remove.
- Cut back bamboo, and use the canes next season as plants supports or stakes in the garden.
- Repair trellises now that leaves have fallen from deciduous plants, allowing better access.
- Check tree ties, stakes and supports. Install windbreaks and tree guards around vulnerable plants.
- Relocate evergreen shrubs (can be done either in autumn and early spring).
- Lift rooted hardwood cuttings produced last autumn (the year before) and plant them out to a permanent location.
- Some perennials plants with long fleshy roots such as horseradish can be propagated by root cuttings, take root cuttings from this time in late autumn until late winter.
- Propagate black, red and white currants and gooseberries from hardwood cuttings.
- Propagate vines such as grapes using hardwood cuttings or ‘eye cuttings’ with a single bud.
- Propagate rhubarb by lifting root, divide it so each piece has one or more buds and replant.
- Harvest and store root crops – now is the time to begin lifting parsnips from the ground, exposure to cold improves the taste.
- Ponds should be cleaned of old plants, and overgrown marginal plants around the pond can be divided.
Vegetables and Herbs to Grow in May (Cool & Alpine Climate)
| May Seeds to Sow and Seedlings to Plant (Cool & Alpine Climate Australia) | Sow/Plant | Harvest (weeks) |
| Broad Beans | dst | 12-22 |
| Corn Salad | d | 5-8 |
| Garlic | plant cloves | 17-25 |
| Mustard Greens | t | 5-8 |
| Rocket | d | 21-35 days |
| Shallots | d | 12-15 |
| Spinach | dst | 5-11 |
| Spring Onions (Bunching Onions) | t | 6-10 |
Key:
d = sow seeds directly into ground
s = sow seeds into seed tray
ds = sow seeds directly into ground or seed tray
t = transplant seedlings (small plants) into larger pots or plant into ground
*= frost tender
**= sow after frost
Download printable PDF version of Gardening Calendar (Australian Cool & Alpine Climate) – May
To help improve these garden calendars, feedback and additional information from readers is greatly appreciated! Australia’s climate varies considerably, and local knowledge of when particular things need to be done in the garden are most helpful to others living in those area, so please feel free to share.