When to plant Sweet Corn in Temperate Australia

Temperate zone — applies to Sydney, Melbourne, Adelaide, Perth, Newcastle and similar areas. Growing elsewhere? Subtropical · Cool · Tropical · Arid.

Sweet corn is sown direct from September to January in temperate Australia, into soil that has genuinely warmed — this frost-tender crop punishes impatience. Seed sits 15–25 mm deep and germinates in 6 to 12 days when conditions are right, with cobs ready in 80 to 120 days. The single most important instruction is geometric: plant in a block of at least four rows rather than one long line, because corn is wind-pollinated and poorly pollinated plants produce cobs with missing kernels. Space plants 20–30 cm apart with 50–90 cm between rows, and feed generously.

Sowing calendar — temperate zone

Green months are your sowing window: September to January.

Growing notes

With the temperate last frost falling around mid-October, September sowings of this frost-tender crop are only for warm, sheltered gardens — cold soil rots the sugary seed and a single frost flattens seedlings. October to December is the heart of the season; January sowings still work because even at the slow end of 80 to 120 days, cobs beat the first frosts of May.

Corn is one of the hungriest vegetables you can grow. Prepare beds with abundant compost or aged manure, then side-dress with a nitrogen-rich feed when plants are knee-high and again at tasselling. Water deeply and regularly — moisture stress while cobs are filling is the second great cause of gappy, half-filled cobs after poor pollination.

That pollination point deserves repeating. Pollen falls from the tassels at the top of the plant onto the silks of each cob below, and in a single row most of it simply blows away. A block at least four plants deep lets pollen find silks whichever way the breeze runs; on still mornings you can help by giving the stalks a shake.

Sow two seeds per station 15–25 mm deep and thin to the stronger — germination takes 6 to 12 days in warm soil. Cobs are ready when the silks turn brown and dry and a pierced kernel bleeds milky juice; clear juice means wait, doughy means the peak has passed.

Sweet Corn at a glance

Companion planting

Grows well with

Bean (Bush): Classic Three Sisters — beans fix nitrogen for corn

Zucchini: Classic Three Sisters variation — zucchini ground cover suppresses weeds

Nasturtiums: Deters aphids; trap crop

Common questions

When do you plant sweet corn in temperate Australia?

Sow direct from September to January, but remember corn is frost tender and the last frost typically falls around mid-October — October to December sowings into warm soil are the most reliable.

Why does my corn have missing kernels?

Poor pollination. Every silk strand must catch a grain of wind-blown pollen to form a kernel, so plant corn in a block of at least four rows rather than a single line.

How long does sweet corn take to grow?

From 80 to 120 days depending on variety and warmth, with germination taking 6 to 12 days in properly warm soil.

How do I know when sweet corn is ready to pick?

The silks turn brown and dry, and a kernel pierced with a thumbnail bleeds milky juice. Clear juice means it needs longer; doughy paste means it is past its best.

Keep exploring