What to plant in your New Zealand garden this August

August is the gardening new year. The days are lengthening, the soil is starting to warm, and anything you plant now has the whole long slow climb to spring to get established. It’s also when the first summer seeds go onto warm windowsills, because eight to ten weeks from now is Labour Weekend — the traditional tomato-planting date.

What you should plant this month depends enormously on where you are. A gardener in Whangārei has a completely different window from one in Alexandra. Our free interactive tool — the Newswire NZ Gardener’s Planting Calendar — lets you pick your region and see exactly what to sow, plant and harvest this month for your patch. Worth keeping open in a tab while you read the rest.

Start summer heat-lovers indoors

Now is the time, everywhere. Sow tomato, capsicum, chilli, eggplant and basil seeds into small pots on a sunny windowsill or a heated propagating tray. Aim for a warm spot (20–25°C) for germination. Don’t plant these out until after the last frost — which in most of the country is around Labour Weekend.

Potatoes — chit now, plant late in warm regions

“Chitting” means sprouting seed potatoes in a light, cool spot for 4–6 weeks before planting. Buy certified seed potatoes now, spread them out in an egg carton in a cool bright room, and let them grow short green shoots. In Auckland and Northland you can plant the first crop by the end of August; the rest of the country waits until September.

Outdoor sowing — the first of the season

• Peas — sow direct. Dwarf varieties need no support; climbing ones need a 1.5m frame.
• Broad beans — final window for a spring crop. Push them into warm-facing ground.
• Onion seedlings — transplant trays of bought seedlings into prepared beds.
• Lettuce, radish, rocket — outdoor sowing starts in warm regions; use cloches elsewhere.
• Spinach — direct sow. It germinates at low temperatures; most other greens don’t.

Fruit trees — the last bare-root window

Garden centres still have bare-root fruit trees into August, but stock is dwindling and the best varieties are gone. If you’ve been dithering, decide this week. After the end of the month, anything you plant will be in a pot and more expensive.

Spring bulbs are flowering

Daffodils are the signal. Their appearance in your garden or on nature strips means the soil is warming enough to plant out seedlings of cool-weather flowers — pansies, violas, primulas and cyclamen. Crocus and snowdrops have been and gone; tulips are still ahead.

Warm north — spring starts early

Auckland, Whangārei and Bay of Plenty gardeners can plant their first potatoes this month, sow the first outdoor salads and start transplanting winter-sown brassicas. Check soil temperature — when it’s consistently above 10°C overnight, carrots and beetroot go in too.

Cold south — keep the lid on

Central Otago, Southland and inland Canterbury are still deep in winter. Frost is still a nightly occurrence. The big jobs this month are finishing pruning, getting the last bare-root trees in, and preparing beds for September planting. Indoor seed-starting can begin but nothing goes outside yet.

What NOT to plant this month

Anywhere in NZ: tomatoes, capsicum, chilli and cucumber outdoors. Even in the warmest regions, the soil is not warm enough to avoid stunting or losing them. Keep them on the windowsill until late October.

Use the tool

The hardest part of gardening in Aotearoa is that generic planting advice — the kind you’ll find on the back of seed packets imported from the UK or California — is almost always wrong for our conditions. Even advice written for New Zealand is often written for Auckland and quietly fails gardeners south of Christchurch.

That’s why we built the Newswire NZ Gardener’s Planting Calendar. Pick your region once, and it shows you exactly what to sow, transplant, and harvest this month — plus a reverse lookup where you can type in any plant (tomato, feijoa, dahlia, pōhutukawa) and see the ideal window for your patch. It’s free, it works on your phone, and it’ll save you a lot of guesswork.

What are you planting this month? Drop a comment below and tell us what’s going in the ground in your garden — and which region you’re in, so other readers can compare notes.

This article was written by AI, briefed to report the facts, hopefully without some of the bias people bring to the job 🙂