On paper, August is when the sowing calendar reopens in New Zealand's cool/mountain gardens — the number of crops with an open sowing window jumps from two in July to thirteen. In practice, how much of that you can act on depends entirely on where you garden. "Cool/mountain" covers a lot of ground, from milder inland districts to high-country gardens still under frost and snow in August, and the sowing windows behind that thirteen are broad national planting dates, not cold-zone-specific ones — so treat the list as what the season allows, not a sign that winter is over. It isn't: this zone's frost period runs right through to November.

That's why the most useful thing to do this month often isn't outdoors at all. A greenhouse, cold frame, or sunny windowsill is where a keen gardener gets a real jump on a short season — raising seedlings under cover now so they're ready to go out the moment the frosts lift. Outdoors, match the list below to your own frosts and altitude, not the calendar's optimism.

Start seedlings under cover — the real job this month

The crops that transplant well are the ones to start now: raised under cover, they run weeks ahead of soil that won't take them yet, and go out once the frosts finish. For an eager gardener, this is the productive answer to a month that's still winter outdoors.

Tomato (sow August–November) is the headline, and a trays-only indoor start. Its transplant window is October–December, but with frost lingering into November here, seedlings started now may wait until late spring before it's safe to plant them out — so don't sow the whole packet at once. Tomatoes are demanding in a cool, short-season zone anyway; Why Tomatoes Fail in Wellington — and What to Do Instead is worth reading first.

Broccoli (sow August–November) is raised in trays and transplanted at four to six weeks — net the young plants against white butterfly the moment they go out. Kale (sow August–October) can be tray-raised or direct sown, and it's the one crop here that actively wants the cold: frost sweetens it. Silverbeet (sow August–May) also takes happily to a tray start if you'd rather get it going under cover than wait for the soil. Growing Silverbeet Year-Round in NZ has the detail.

Long-season alliums: get them in now

Two crops need to go in this month simply because they take so long to mature, the same logic that put garlic in the ground earlier in winter.

Onion (sow July–September, harvest January–March) is a long-season crop at roughly 160–200 days. Direct sow it, and keep it out of freshly manured or high-nitrogen ground, which drives leaf at the expense of the bulb.
Shallot has the tightest window, August–September: push bulbs in 5cm deep and 15cm apart, sizing up for a January–February harvest.

Cool-hardy crops to direct sow

These handle cold soil and are sown where they'll grow — the roots especially resent being moved, so there's no starting them indoors. In a cold garden they wait for the milder pockets of the zone or a break in the frosts, and germination is slow, so don't be alarmed if seed sits a while.

  • Broad beans (sow August–October, harvest December–February) are the classic winter legume. Direct sow, and pinch out the growing tips once flowering starts to take the pressure off aphids. In the hardest-frost gardens an August sowing is slow to establish — a cloche helps.
  • Beetroot (sow August–May) tolerates frost from the outset. Sow direct and thin to about 10cm; it doesn't like being transplanted.
  • Turnip (sow August–October) has a deliberately narrow window — it's a cool-season root that turns woody and bolts in summer heat, so this stretch is its real season. Direct sow and thin to 10cm.
  • Radish (sow August–April) is the fast one — sow a short row now and another in a fortnight rather than a single big batch.
  • Mizuna (sow August–December) and pak choy (sow August–May) are both quick cut-and-come-again greens; sow a little and often, and keep taking outer leaves.
  • Coriander (sown July–November) carries on from last month — a cool-season herb that runs to seed far less readily sown now than in summer. If it's bolted on you before, Why Is My Coriander Bolting Immediately in NZ Cool/Mountain? explains why a cool start is the fix.

What's still coming out of the ground

The harvest list is down to its last two, both closing this month:

  • Carrot is in the final month of its harvest window. Lift the rest rather than leaving roots to sit in cold, wet soil.
  • Jerusalem artichoke also closes out in August. Dig what remains before spring growth restarts — and set aside a few tubers to replant, since that's next season's crop.

Recommended cultivars

  • Onion & shallot: we don't have specific cultivars catalogued yet — choose a NZ-suited long-day onion from your usual supplier.
  • Broad beans: Coles Prolific (Kings Seeds NZ), direct sown; or Red Seeded (Koanga Institute), tray-raised and transplanted at 40cm.
  • Beetroot: Bulls Blood (Kings Seeds NZ) or Bull's Blood (Koanga Institute) — dark-leaved and happy with a cool sowing.
  • Broccoli: Belstar F1 (Kings Seeds NZ), or de Cicco (Koanga Institute) pricked out and transplanted at 30cm.
  • Kale: Blue Ridge F1 (Kings Seeds NZ), or Borecole (Koanga Institute) — transplant at 40cm, or broadcast for baby leaves.
  • Coriander: Picante (Kings Seeds NZ), direct sown; or NZH (Koanga Institute) for tray-raising.
  • Silverbeet: Ford Hook Giant (Kings Seeds NZ) for bulk, or Bright Yellow (Kings Seeds NZ) for colour.
  • Tomato: Albenga Oxheart (Kings Seeds NZ); or Alma (Koanga Institute), a drying type staked at 50cm once it's finally planted out.

Know your zone? Explore the full NZ Cool/Mountain Planting Calendar for month-by-month sowing and harvest timing.