What to do in your garden: August

Our experts share their seasonal tips so that you can add them to your to-do list this month and get ready for spring!

Get ready for a summer harvest of tomatoes.
Photo: Kirsten Bresciani

Give your compost heap a winter boost in readiness for spring planting. Add fallen leaves, leafy weeds and animal manure. Keep it just moist.


Tomato vines are dripping with fruit. To stop birds stealing them, pick them before they are completely ripe and finish ripening inside.

Prepare soil with compost and well-rotted manure. Then plant taro, cassava and cocoyam. These will grow in full sun or semi-shade.

Give custard apple trees a light prune after harvesting. Remove tall branches to promote lateral growth and trim low growth to aid air movement within the canopy.


Continue sowing dill, Florence fennel, parsley, cabbage and Asian greens for regular crops. Plant thickly and start to harvest at micro-green stage, then again when they are sturdy seedlings, leaving the rest to develop to full size.

Plant passionfruit in early August. Choose a sunny spot and provide a solid support such as lattice or wire fence. Prepare the planting hole with plenty of compost or well-rotted manure. Remove the tip of the vine to encourage horizontal branching.

Apply potash around the base of fruit trees and water it in well. This is important to maintain tree health and fruit quality.


With the warming climate, aphids are appearing earlier and are often seen towards the end of winter. Initially just squash them, but if there are too many then try hosing off with a strong jet of water, or spray with a weak soap spray. 

To stop ants farming and spreading aphids and scale, put a sticky collar around the trunks. There are a number of horticultural glues available that work best when used with a cardboard band or collar.

Get a head start on spring crops by sowing seeds of frost-tender plants in a glasshouse or indoors on a sunny windowsill. Include tomato, capsicum, eggplant, basil and zucchini.

Warm Temperate

Plant shallot bulbs. Place them buried about half way up the bulb, 30cm apart into compost-rich soil. Each bulb will form a cluster of six to 10 new bulbs.

Divide late-season perennials such as tarragon and costmary by digging up the whole clump and replanting pieces with roots growing, either into the ground or pots. It reinvigorates the clump and provides new plants to give to friends.

Sow marigold and dianthus seeds for edible flowers that can be harvested in spring. Marigold petals are delicious in salads and with rice, while clove-scented and flavoured dianthus flowers are delectable with sweet dishes.

Cold Temperate

Plant bare-rooted fruit trees. Carefully trim damaged roots and soak overnight in diluted seaweed extract. Dig an appropriately sized hole, mounding up the soil in the middle and spreading the roots over the mound. Backfill with soil and firm down so the soil is well below the graft. Water well.

Sow salsify seeds. It likes the same conditions as carrots and parsnip and takes up to six months to develop the white-fleshed roots.

Check deciduous fruit trees, removing dead or diseased growth and those that cross over, opening up the framework. Apply well-rotted manure and compost around the base out to the drip-line.

Our latest issue, which is onsale until August 6, has a detailed feature by Penny Woodward about growing heirloom tomatoes, including how to grow from seed! Head here for more information about getting an issue delivered to your door. 

First published: October 2019

Related topics

Gardening Basics, All Gardens, What to do now