Short answer: August is the temperate zone's biggest sowing month by far. Eleven new sowing windows open at once — broccoli and kale for the first time all year, tomato's indoor sowing, and a run of direct-sow staples from beetroot to turnip. After a quiet June and a two-crop July, this is the month the calendar properly reopens.
The NZ Temperate August Growing Context
Soil is still cold and frosts are still regular (the frost period runs to November), but day length is lengthening enough to trigger a wave of sowing windows regardless. Most of what opens this month is hardy enough to handle cold soil and slow early growth; the exceptions — tomato, basil, courgette, cucumber — either need to start indoors or wait for the ground to warm further.
Typical August conditions in temperate gardens:
- Still within the frost period, but the coldest weeks are behind
- Eleven sowing windows open for the first time this year
- Two crops (coriander, onion) continue from July
- Carrot and jerusalem artichoke remain the main harvest
- Trays and indoor space become the bottleneck, not soil temperature
What to Sow This Month
Broccoli — first sowing of the year
Broccoli's window runs August through November, the only time it opens all year. Raise in trays and transplant at 4–6 weeks; net young plants against white butterfly from the day they go out, since an unprotected planting can be stripped within days.
Cultivar picks: Belstar F1 (Kings Seeds NZ), raised as transplants; or de Cicco (Koanga Institute), sown into trays and pricked out at 2.5cm spacing, transplanted at 30cm — protect seedlings from slugs and snails while young.
Kale — first sowing of the year
Kale's window runs August through October. Direct sow or raise in trays — both work — and don't worry about frost once established: kale is genuinely one of the hardiest crops here, and cold weather improves flavour rather than threatening the plant.
Cultivar picks: Blue Ridge F1 (Kings Seeds NZ), raised as transplants; or Borecole (Koanga Institute), pricked out at 2.5cm spacing and transplanted at 40cm, or broadcast direct for a baby-leaf mesclun harvest instead of full-sized plants.
Tomato — start indoors
Tomato's sowing window opens in August too, but entirely indoors — this is a trays-only start, with transplanting out only after the last spring frost (October–December, depending on how the season runs). An August sowing now buys the lead time a spring-only start doesn't have.
Cultivar picks: Albenga Oxheart (Kings Seeds NZ), raised as transplants; or Alma (Koanga Institute), a drying tomato pricked out at 3cm spacing, potted on as it grows, and staked once planted out at 50cm spacings in rows.
Also new this month
- Beetroot — sows August through May; direct sow, thin to 10cm, frost-tolerant from the start.
- Silverbeet — sows August through May; one of the few crops here that keeps producing right through winter once established.
- Broad Beans — sows August through October; direct sow, pinch tops at flowering to deter aphids.
- Pak Choy — sows August through May, an unusually wide window; cut-and-come-again, direct sown.
- Radish — sows August through April; very fast-growing, succession sow every 2 weeks.
- Mizuna — sows August through December; quick cut-and-come-again Japanese green, succession sow every 2–3 weeks.
- Turnip — sows August through October only, a narrower window than most on this list; dislikes summer heat, so this and the next couple of months are its real window.
- Shallot — sows August through September only, the tightest window this month; plant bulbs 5cm deep, 15cm apart, similar timing to garlic.
Still open: Coriander and Onion
Both opened last month and continue through August — coriander through November, onion through September. Neither is new, but both are still very much sowable if you haven't started yet.
Not yet: Basil, Peas, Cucumber and Courgette
All four are classic spring/summer crops, but none open until next month or later in the temperate zone — basil and peas from September, cucumber from October, courgette from November. Getting ahead of the data here just means cold, slow-germinating seed sitting in trays for no benefit.
What to Harvest This Month
- Carrot — well within its long harvest window, unaffected by the last of the frosts.
- Jerusalem Artichoke — still being dug as needed; tubers keep best left in the ground, and this is its last month before the window closes at the end of August.
Garden Jobs for August
Get trays going before beds are ready
Broccoli, kale and tomato all start in trays this month, well before the ground is warm enough to plant most of them out. Getting seed started now avoids a bottleneck later when everything wants transplanting at once.
Net brassicas from day one
White butterfly pressure on broccoli and kale starts as soon as seedlings go in the ground, not later in the season. Net at transplanting rather than waiting for the first signs of damage.
Finish the last of the jerusalem artichoke harvest
The window closes at the end of this month. Dig what's left rather than letting it run into September, when new growth starts competing with anything still in the ground.
Common August Mistakes
Sowing tomato, basil or courgette direct outside
Tomato needs an indoor start this month; basil, courgette and cucumber don't open at all yet. Direct-sown seed for any of these in August cold soil mostly just rots.
Skipping the net on brassica seedlings
Broccoli and kale seedlings are at their most vulnerable to white butterfly right after transplanting. A few days unprotected can undo weeks of tray-raising.
Treating August like an ordinary sowing month
Eleven windows opening at once is unusual — most months on this calendar open one or two. Missing the start of August's rush means catching up throughout spring instead of sowing on schedule.
Looking Ahead
September keeps most of August's windows open and adds basil and peas to the mix, while broccoli and kale move from trays into the garden as transplants. Jerusalem artichoke's harvest closes out this month — expect bare ground where it was until next year's tubers go back in.
Ready for next month? See *What to Plant in NZ Temperate in September*, or explore the full NZ Temperate Planting Calendar →.