Gardening Calendar (Australian Temperate Climate) – December

December is the first month of summer, and with the warmer weather gardens explode into life – lush, abundant and awesome to behold. With the days getting longer as we progress towards the longest day of the year, the summer solstice, there’s more time to enjoy the garden and the great outdoors!

During this time, temperatures can reach extremes as the days heat up, and gardens can get quite dry, so keeping up with the watering is important. Pests will also emerge with the warmer weather so keep an eye out for them!

‘Chop & Drop’ any broad beans or peas after harvesting, ‘chop’ the tops at ground level, and ‘drop’ on top of the soil as mulch, leave the roots in the ground to return any nitrogen in the root nodules to the soil.

As strange as it may seem, early summer is the time to sow some winter brassicas such as broccoli, brussels sprouts, cauliflower and swedes, so they can be harvested in winter.

Things to Do This Month:

  • Top up or add extra mulch around fruit trees and plants to retain moisture in the soil and prevent water loss from evaporation (keep mulch away from plant stems and trunks as this can cause stem rot/collar rot).
  • Propagate climbers by layering and propagate strawberries by pegging down runners onto soil.
  • Propagate plants by taking softwood (green) cuttings from now till January (after which they begin to harden off).
  • Last chance to plant potted fruit trees and vines to beat the summer heat (having roots, can be planted anytime, but best in spring & autumn). Make sure you pick a day when the weather is mild!
  • Continue tying growing vines and brambleberries such as blackberries and their hybrids back to supports or wires.Thin out fruit on plum trees if there is a risk of branches breaking.
  • Last chance to plant tomatoes and capsicum seedlings.
  • If you need to add new fish to ponds or water gardens, this is an ideal time as they acclimatise easier in the warmer weather.

Vegetables and Herbs to Sow:

Sow in December Harvest (weeks)
Amaranth ds 7-8
Angelica ds 18 months
Asparagus d 2-3 years
Asparagus Pea d 8-11
Beetroot ds 7-10
Borage ds 8-10
Burdock d 17-18
Cape Gooseberry ds 14-16
Carrot d 12-18
Chilli s 9-11
Chives ds 7-11
Choko d 17
Climbing beans d 9-11
Cucumber d 8-10
Dwarf beans d 7-10
French tarragon d 30-40 days
Kohlrabi d 7-10
Lettuce ds 8-12
Mustard greens d 5-8
Oregano s 6-8
Parsley ds 9-19
Pumpkin ds 15-20
Radish d 5-7
Rosella s 21-25
Rosemary d 12 months
Sage d 18 months
Silverbeet ds 7-12
Sunflower ds 10-11
Sweet corn ds 11-14
Turnip d 6-9

d = sow directly into ground
s = sow in seed tray
ds = sow directly into ground or seed tray
*= frost tender
**= sow after frost

Download printable PDF version of Gardening Calendar (Australian Temperate Climate) – December

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