Australia

Arid inland Australia: heat, drought and what to plant when

Frost and rain

Frost	Light frost some years
First autumn frost	late autumn
Last spring frost	early spring
Note	BoM's frost maps confine frost to late autumn through early spring, and BoM and CSIRO count about eight potential frost nights a year at Marree and four at Tibooburra for 1989 to 2018, down from 13 and eight, so the dates are broad and the nights few.
Rainfall	Low rainfall

The dry inland covers the arid heart of the continent, from the deserts of the Northern Territory and Queensland to the north of South Australia. Summers are extremely hot, evaporation is very high, droughts are prolonged, and winter nights are cold enough for occasional frost. BoM and CSIRO report more consecutive days above 40 °C in the Arid Lands and above 42 °C around Alice Springs in the last 30 years. For a gardener that makes two planting windows, in autumn and in spring, and a long job in between, which is keeping plants alive with shade, mulch and careful water.

Frost

BoM’s frost maps show potential frost days mainly confined to late autumn through early spring. Frost is not frequent in the arid inland, and the guides count few potential frost nights: about eight a year at Marree and four a year at Tibooburra for 1989 to 2018, down from 13 and eight in the previous 30 years. More of them occur through dry winter and spring periods, when soil moisture is low and cloud is infrequent. No first or last frost date is published for the arid inland, so this page gives the broad season only.

Frost forms on clear, calm nights, and cold air drains into low ground, so a hollow in the garden is the first place to freeze. Protect tomatoes, capsicums, basil and young seedlings with fleece or a hessian sheet before dusk, and take it off in the morning. Frost-tender plants such as aloe and yucca do better in a sheltered, warm corner or a pot that comes under cover.

Rain and watering

Rain here is an event rather than a season. BoM and CSIRO describe rainfall in the Alice Springs region and the Arid Lands as unreliable throughout the year, with summer the slightly more reliable season around Alice. The Alice Springs region receives about 330 mm a year and the Desert Channels about the same, while the South Australian Arid Lands get about 180 mm. At Alice Springs two thirds of rain events of 50 mm or more fall in summer, and one such event occurs about once a year. In the Desert Channels the wet season runs from October to April, with a useful rain event about twice a year.

With so little rain, every garden depends on stored water, mulch and drip lines. Water early in the morning or late in the evening, deeply and less often, and group plants by how much water they need. Shade cloth over young plants in the heat is worth the cost. Indoors, the heat dries pots quickly in summer, so check them often, and keep tender plants off cold glass on winter nights.

Month by month

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

January

Extreme heat, with long runs of days above 40 °C. Sow only the heat lovers, such as okra, melons, pumpkin and eggplant, under shade cloth, and water at dawn. Mulch everything. The general list is on January, south of the equator.

February

Still very hot. Use the month to prepare: dig compost into the beds that will take the autumn crops, mend the drip lines and make the shade frames. Sow only where you can water twice a day. The general list is on February, south of the equator.

March

The heat eases and the first window opens. Sow broccoli, cabbage, carrots, lettuce, onions, spinach and silverbeet, and sow broad beans. Plant daffodils and hyacinths. The general list is on March, south of the equator.

April

The best sowing month, with warm soil and frost still weeks away. Sow beetroot, carrots, kale, lettuce, onions, peas, radish and spinach, and plant garlic and potatoes. Keep the seedbeds moist. The general list is on April, south of the equator.

May

Late autumn, and the first potential frost nights. Sow peas, broad beans, silverbeet and spinach, and plant garlic. Cover tender plants on clear, still evenings. The general list is on May, south of the equator.

June

Winter, with frost on clear nights. Sow lettuce, peas and spinach in sheltered beds, and prepare planting holes for the bare-root fruit trees and roses that go in next month. Water by hand if there is no rain. The general list is on June, south of the equator.

July

The coldest month. Prune the roses, fruit trees and vines, and keep fleece within reach for the frost nights. Leave frost-damaged growth in place until spring. The general list is on July, south of the equator.

August

The frost is easing but has not finished. Start tomatoes, capsicums, chillies and sweet potatoes under cover, and plant potatoes and strawberries. Mend the irrigation before the heat. The general list is on August, south of the equator.

September

The spring window opens. Plant out tomatoes, capsicums and eggplant once the last frost has gone, and sow cucumbers, pumpkin, beans and zucchini. Mulch after watering. The general list is on September, south of the equator.

October

Warm and dry. Sow beans, cucumbers, melons, sweet corn, pumpkin and sunflowers, and begin deep watering twice a week. The heat of summer is a few weeks away. The general list is on October, south of the equator.

November

The heat arrives. Sow okra, melons and sweet potatoes, plant in the evening, and shade anything small. Water the hole before the plant goes in. The general list is on November, south of the equator.

December

Extreme heat again. Sow only the toughest crops, mulch deeply and water before dawn. Do not start a new bed you cannot water through January and February. The general list is on December, south of the equator.

Plants that belong here

Century plant wants full sun, poor gritty ground and no water through the cold months, because it dies of winter wet rather than winter cold.
Aloe vera comes from hot, bright, stony ground where rain is rare and drains away at once, but needs bringing in before the first frost.
Bougainvillea flowers under stress, with a proper drying out between soakings, and needs frost protection.
Spineless yucca is tough, dry loving and wants the brightest spot you have, with protection from frost.
Rosemary comes from dry coastal hills and does better with less water than with more.
Lavender takes frost and wants full sun and sharp drainage.
Thyme wants poor soil, full sun and long dry spells.
Oregano is grown hard, dry and in full sun.
Geranium wants sun, sharp drainage and a proper dry spell between waterings.

Questions from the margin

Does it frost in the Australian outback?

Yes, on clear winter nights, though not often. BoM and CSIRO count about eight potential frost nights a year at Marree and four at Tibooburra for 1989 to 2018, down from 13 and eight in the previous 30 years, and more of them come after a dry winter and spring.

How much rain does the arid inland get?

Little, and unreliably. BoM and CSIRO give about 330 mm a year for the Alice Springs region and the Desert Channels, and about 180 mm in the South Australian Arid Lands, with rainfall unreliable in every season. At Alice Springs a rain event of 50 mm or more occurs about once a year, mostly in summer.

When should I plant vegetables in an arid garden?

In autumn, from March to May, and in spring, from August to October, with the heat of January and the frost of June and July on either side. Shade cloth, mulch and drip watering decide whether anything planted in summer survives.

Checked against

The figures and the advice on this page were checked against the sources below, and where they disagree the page says so.

Read on

Planting almanac for this region: Opens the almanac with this region and its hemisphere already chosen.