December in Adelaide is the height of summer, heat and water management are the priority. Here’s exactly what to sow from seed, plant as seedlings, and harvest this month in a mediterranean/temperate climate, tuned to Adelaide’s frosts and temperatures, not a generic national calendar.
Typical Temps
7-33°C
winter low to summer high
Frost
Frost-free (plains), light frosts July-August in Hills
Climate Zone
Mediterranean/Temperate
South Australia
Frost watch: Adelaide's plains rarely frost, but the Adelaide Hills and inland areas get light frosts in winter. Hold tender seedlings until early September in cooler suburbs. See frost dates for every city →
Adelaide's extreme summer heatwaves (40°C+) can kill vegetable plants within hours, keep shadecloth on hand and water deeply the day before forecast heatwaves.
The Adelaide Hills is its own microclimate, if you garden above 400m, treat your conditions more like Canberra and expect frosts from June to September.
Adelaide's low summer rainfall means drip irrigation is essential, hand-watering raised beds in 38°C heat is exhausting and inefficient.
Adelaide tap water is among Australia's most alkaline, check your soil pH regularly and add sulphur or acidic compost to correct alkalinity, which blocks nutrient uptake.
From the makers
This calendar tells you what's possible in December, Plant Planner tells you exactly how many of each crop to grow for your family, how to arrange them in your beds, and sends reminders so you never miss a window.
In December, Adelaide gardeners can sow Beans, Spring Onion from seed, and plant out Eggplant (last), Sweet Potato, Capsicum as seedlings. Adelaide sits in the Mediterranean/Temperate climate zone, so these picks are timed to local conditions.
December falls in the height of summer, heat and water management are the priority. In Adelaide, expect winter lows around 7°C and summer highs near 33°C. Adelaide's plains rarely frost, but the Adelaide Hills and inland areas get light frosts in winter. Hold tender seedlings until early September in cooler suburbs.
December is generally not the ideal window for tomatoes in Adelaide, they're a warm-season crop sensitive to frost. Use December for the season's recommended crops above, and check the Adelaide calendar for the best tomato-planting months.
In a Adelaide garden, December typically brings harvests of Tomato, Zucchini, Cucumber, Beans, Garlic, Spring Onion, Basil. Actual timing depends on when each crop was planted.