Temperate Australia: frost, rain and what to plant when

Frost and rain

Temperate Australia is the country of the big coastal cities: Sydney, Melbourne, Adelaide, Perth and the coastal south east. Summers are warm and winters are cool. The coast is mild, and the outer suburbs and the hills behind are colder, so the same city can hold gardens with almost no frost and gardens with plenty. For a gardener the first rains of autumn matter as much as the frost does, because they set the start of the planting year.

Frost

BoM’s frost maps show potential frost days mainly between late autumn and early spring, and rising with elevation. BoM and CSIRO give the end of the frost risk in this zone, from records for 1989 to 2018, as typically the first week of August at Mundaring in the Perth hills, the first week of September at Richmond in western Sydney, and by November around Adelaide at Rosedale and Nuriootpa. The latest frost nights on record were 22 September 2018 at Mundaring and 28 September 2018 at Richmond, and in Adelaide into November and December.

Central Melbourne is milder. Its likely frost days fell from four a year to two, while Laverton in the outer west fell from 26 a year to 15, and in the Port Phillip region the risk stayed the same through October and November. No first-frost date is published for these cities, so the start of the season is best taken as late autumn.

Frost forms on clear, calm nights, and cold air pools in hollows, so the low corner of a garden is the first to freeze. The reports also find more frost after a dry winter, with about nine more nights at Richmond and eight more in the Perth region. Protect tender citrus, young tomatoes and frost-tender shrubs with fleece before dusk.

Rain and watering

Rain falls at different times in different cities. BoM and CSIRO describe winter rain as reliable in Perth and Adelaide, with summer unreliable, and summer as the reliable season in Greater Sydney, with winter unreliable. In Port Phillip rainfall is moderately reliable throughout the year, winter most of all. Annual totals are about 930 mm in Greater Sydney, 810 mm in Port Phillip, 790 mm in the Perth region and 570 mm around Adelaide.

The autumn break, the first useful autumn rain, usually arrives from mid April in the north east of Port Phillip to late May in the south west, and in the first or second week of May in Perth. Until it arrives, water by hand. In Perth and Adelaide summer rain is unreliable, so the hose does the work. In the house the same dry summer heat dries pots quickly, while the cool winter slows growth, so water houseplants less often from June.

Month by month

Each month below adds the local timing to the matching southern hemisphere page, which has the general list.

January

Midsummer, hot and dry in Perth and Adelaide and wetter in Sydney. Sow beetroot, carrots, leeks, lettuce, silverbeet and kale for autumn, into a drill watered the night before. Water early and mulch. The general list is on January, south of the equator.

February

Late summer. Sow broccoli, cabbage, cauliflower and leeks in trays, out of the hottest sun, and sow lettuce, carrots and radish. Take cuttings of lavender and pelargonium. The general list is on February, south of the equator.

March

The heat breaks, and the rain starts to return in the south and west. Plant spring bulbs, and sow broad beans, spinach, onions, parsnips and radish. Keep the winter brassicas growing. The general list is on March, south of the equator.

April

The autumn break arrives in Melbourne, from mid April in the north east of the region. Plant garlic, onion sets and shallots, and sow peas, lettuce and spinach. Make the most of the warm soil. The general list is on April, south of the equator.

May

The autumn break reaches Perth in the first or second week of May. Plant garlic, sow broad beans and peas, and plant hardy perennials so that the roots settle through winter. The first frosts may reach the hills. The general list is on May, south of the equator.

June

Winter, with reliable rain in Perth and Adelaide. Prepare planting holes for bare-root roses and fruit trees, plant shallots, and sow broad beans, peas and lettuce. Frost cloth stays by the back door. The general list is on June, south of the equator.

July

The coldest month. Prune roses, fruit trees and vines, and keep planting bare-root stock. The frost risk is highest in the hills, so protect new growth. The general list is on July, south of the equator.

August

Late winter. In the Perth hills the frost risk is typically over by the first week. Sow peas, beetroot, lettuce and spinach, plant potatoes and strawberries, and start tomatoes under cover. The general list is on August, south of the equator.

September

Spring. In western Sydney the frost risk has typically ended by the first week. Sow beans, carrots and sweet corn, plant out potatoes, and sow tomatoes, capsicums and basil under cover. The general list is on September, south of the equator.

October

Plant out tomatoes, capsicums, cucumbers and zucchini, and sow beans and sweet corn where the frost has ended. In outer Melbourne and around Adelaide keep fleece handy. The general list is on October, south of the equator.

November

Mulch the summer garden and water deeply. Plant the heat-tolerant annuals, and sow another round of beans and basil. The frost risk has typically ended even around Adelaide. The general list is on November, south of the equator.

December

Early summer. Pick regularly, deadhead and water the soil rather than the leaves. Sow kale, parsnips and cabbage in trays for winter. The general list is on December, south of the equator.

Plants that belong here

• Lavender wants sun, sharp drainage and poor soil, and wet roots kill it faster than frost.
• Rosemary comes from dry coastal hills and takes several degrees of frost, but not waterlogged ground.
• Rose is lifted dormant and planted bare root through winter.
• Tomato is killed by frost, so the calendar is built backwards from the last frost.
• Lemon wants bright light and a cool but frost-free winter rest.
• Pot marigold is sown in autumn for winter and spring colour and flowers until frost.
• Sweet pea is sown in autumn and grows through the cool weather.
• Garlic needs the cold months, so plant it in autumn.
• Agapanthus takes a light frost and wants sun all day.

Questions from the margin

Read on

Planting almanac for this region

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