What to do in your garden in: December

Our regional gardening to-do list will help you prepare for the hot months ahead!

Now is a good time to plant leeks.
Photo: iStock

Continue to remove weeds to stop them from seeding and spreading. Remember the old saying, “One year’s seeds is seven years’ weeds”Penny Woodward has collected together advice from several of our regular contributors with some great ideas about what to do in your garden now.


Re-pot mints including Vietnamese mint and spearmint. Trim the tops and the roots and plant in a 50/50 mix of compost and potting mix.

Keep an eye out for grasshoppers. Pick them up and drop into soapy water in the early morning when they are sluggish. Alternatively, neem spray is now licensed for grasshopper control.

Leafy greens suffer stress in hot weather so water them twice a day and consider creating shade for the hottest part of the day.


Sow a repeat crop of sweetcorn. These are hungry plants so give the soil all the compost you can spare. Watch out for corn earworm, the larvae of a moth. Squash any caterpillars and spray with Bt (Bacillus thuringiensis).

Don’t delay in planting rosella seedlings into raised beds. The sooner you plant, the greater the return.

Coriander plants love bolting to flower as soon as the weather warms up. The upside is the mass of seeds that follows. Use both to sow next year and in the kitchen.


Identify plants needing protection from hot summer winds and sun then construct simple frames around them. This way you can quickly throw shade-cloth or heavy netting over whenever the need arises.

Plant guava, rosella, chilli, babaco and passionfruit into compost-rich soil with good water-holding capacity.

Aphids love new growth on many different plants. Look out for them on citrus, capsicums, roses, onions and beans. Squash or spray with soap or pest oil sprays.

Warm Temperate

Mulch as much of your garden as you can, including your pots. Using quick-rotting organic lucerne hay, pea straw or sugarcane mulch will also add organic matter to the soil. Ensure the soil is damp before mulching.

Pear and cherry slugs start to make its appearance about now. Try mulching the ground at the base of the trees with wet newspaper and straw. This will stop the pupated adult sawfly from appearing. Water the soil well before mulching.

If you are re-potting plants or planting new ones, add extra coir to the potting mix to increase the water-holding capacity. Grow some vegies in wicking pots or beds, which provide a constant well of water beneath the pot or bed, wicking moisture to the plants as needed.

Cold Temperate

In any beds you are resting, sow green manure crops such as cow pea, mung bean, soya bean or millet. Dig in before flowering to add organic matter and improve soil.

It’s a good time to plant leeks. Sow the seeds into a shallow drill of moist soil, cover with soil and keep moist until they sprout. Start to thin when seedlings are 20cm high. Use the thinnings in salads and sandwiches.

Globe artichokes are ready to harvest. If you cut them while the buds are still small then the whole bud can be eaten without worrying about the central ‘choke’. Alternatively, wait until the buds are bigger and process them as normal.

First published: October 2019

Related topics

Gardening Basics, All Gardens, What to do now