May is the last-call month in New Zealand's temperate garden: every crop still open for sowing — garlic, beetroot, carrot and silverbeet — closes its window at the end of this month. Frost is now a regular feature (the temperate zone's frost period runs April through November), so this is also the month to get the last frost-tender harvests in and settle the garden into its winter shape.

The NZ Temperate May Growing Context

Soil is cooling fast and growth has slowed across the board. Anything sown now needs to establish before the coldest part of winter, which is why May is a hard cutoff rather than a soft one — sow late and seedlings spend winter struggling instead of building roots.

Typical May conditions in temperate gardens:

  • Regular frosts, with cold nights the norm rather than the exception
  • Cooling soil that slows germination compared with April
  • The last sowing window for all four crops still open this month
  • A shrinking harvest list as the last summer stragglers finish
  • Bare patches left by finished crops ready for winter mulch or cover

What to Sow This Month — Last Call for All Four

Garlic — last month to plant

Garlic's sowing window runs April through May, so this is the final month to get cloves in the ground. Depth and spacing don't change for a late planting — 5cm deep, 15cm between cloves — and the roughly seven-month run to harvest still lands in November–December. Miss May and the window doesn't reopen until next April.

Cultivar picks: the same two Koanga Institute varieties recommended in April hold for a May planting — Rocombole Early Red on 10–12.5cm diagonal spacings, and Elephant at 15cm on the diagonal where you want bigger cloves. Work compost or well-rotted manure into the bed first, and snap Elephant's flower heads off while they're young so the plant's energy goes into the bulb.

Beetroot — last month to sow

Beetroot's window runs August through May, so this is the final chance for an autumn sowing. Sow straight into the bed — beetroot resents being transplanted — and thin to roughly 10cm spacing. Light frost won't bother it, which matters now that cold nights are the norm.

Cultivar pick: Bulls Blood (Kings Seeds NZ) — copes well with the cooler end of the sowing window and adds deep red foliage to the bed.

Carrot — last month to sow

Carrot's window runs September through May. As always, sow in place rather than in trays — transplanted carrots fork — and hold seedbed moisture through a germination that runs slower than it did even a month ago.

Cultivar picks: Amsterdam Sprint (Kings Seeds NZ) is the safer bet this late in the window, fast enough to size up before the coldest weeks. Akaroa Long Red (Koanga Institute) remains an option where the soil is deep and loose enough to suit a long-rooted heritage variety.

Silverbeet — last month to sow

Silverbeet's window runs August through May, closing out alongside beetroot and carrot. Sow it directly, or start it in trays and slot the transplants into whatever spaces the finished summer crops have left behind. It's one of the few vegetables here that will keep producing right through winter once established.

Cultivar picks: Ford Hook Giant (Kings Seeds NZ), direct sown, is the heavy-cropping workhorse; Bright Yellow (Kings Seeds NZ) is worth raising in trays if you want some colour on the winter bed alongside the eating.

Not yet: Broccoli and Kale

Both remain off the list until August, when their sowing windows open in the temperate zone. Sowing now means seedlings face the coldest, shortest-day weeks of winter with no head start — wait rather than force it.

What to Harvest This Month

May's harvest list is thinner than April's, with several crops finishing alongside the last of the roots and greens:

  • Beans (climbing), lettuce and peas — all close out their harvest windows this month. Pick everything usable before they finish for the season.
  • Beetroot, carrot and silverbeet — well within their long harvest windows and unaffected by frost.
  • Pumpkin — still within its harvest window until June. Test the skin with a thumbnail: once it no longer dents, cut the fruit and give it a spell curing in the sun before it goes into storage.

Garden Jobs for May

Get the last sowings in before the cutoff

Garlic, beetroot, carrot and silverbeet all close their sowing windows at the end of May. Treat this as a deadline rather than a suggestion — nothing reopens until spring or, for garlic, next April.

Mulch beds as they empty out

As beans, lettuce and peas finish, clear the beds and mulch rather than leaving soil bare over winter. It protects soil structure and suppresses weeds until spring sowing resumes.

Check garlic and root crops after frost

Frost doesn't harm established garlic, beetroot, carrot or silverbeet, but it's worth checking beds after a hard frost for any heaving of newly planted cloves and firming them back in if needed.

Common May Mistakes

Missing the sowing deadline

Once May ends, garlic, beetroot, carrot and silverbeet are all off the table until spring or later. Waiting for "one more warm week" before sowing is the single easiest way to lose the window entirely.

Leaving finished crops in the ground

Spent beans, lettuce and pea plants left in place tie up bed space that could go to winter mulch or soil-building cover instead. Clear them as they finish rather than waiting for a full bed turnover.

Sowing broccoli or kale early to compensate for a missed window elsewhere

Neither crop's window opens until August regardless of what else has closed. Sowing now just means a harder winter for the seedlings, not a shortcut back into season.

Looking Ahead

June has no new sowing windows open in the temperate zone — it's a maintenance month, focused on protecting what's already growing and keeping beetroot, carrot and silverbeet ticking over until the next spring windows open.

Ready for next month? See *What to Plant in NZ Temperate in June*, or explore the full NZ Temperate Planting Calendar →.