Almost always, the plant is simply young and still throwing male flowers only. Courgettes carry separate male and female blooms, and every plant runs all-male for its first week or two before the females — each with a tiny courgette already swelling behind the petals — start opening alongside them. Fruit needs both kinds open together, with pollen actually moving between them. If female flowers have shown up and the little fruit behind them is shrivelling instead of swelling, over-feeding or a genuine pollination miss is the more likely story.

Work Out Which Flowers You've Got

  • Male flowers sit on a bare, thin stalk — nothing behind the bloom.
  • Female flowers carry a miniature courgette right behind the petals already.

An entirely bare-stalked plant just hasn't reached the female stage yet. That's normal, not a fault — give it another week or two rather than assuming the plant is doing something wrong.

The Most Common Reasons

Bees are reliably active through this zone's warm season, which puts sub-tropical in the same picture as temperate rather than the cooler zones further south, where cold snaps regularly ground pollinators outright:

  1. Only male flowers so far. The default explanation, and nothing to act on.
  2. Too much nitrogen. A dark, leafy, vigorous plant throwing plenty of foliage but few flowers or fruit has usually had too rich a feed — energy is going into leaves instead of setting fruit.
  3. A genuine pollination miss. Rarer here than the two above, but it happens during a run of wet or overcast days: a female flower is only receptive for a few hours the morning it opens, and needs several visits in that window to set properly.
  4. Shade or overcrowding. Plants packed too close or without full sun flower poorly and are harder for a bee to reach in the first place.

Timing Gives You More Slack Here Than Most Zones

Courgette sows September through December in this zone — a full two months earlier than temperate's November–February start — and the harvest window it feeds into runs November through May, noticeably longer than temperate's January–April. A slow start on fruit matters less here simply because there's more season on either side of it to make up the difference. If your plant went in on the later end of the window, give it time before assuming something's actually wrong.

What to Do Now

  • All male flowers? Wait — the females are close behind.
  • Females dropping unset? Hand-pollinate: take a male flower, peel its petals back, and dab the exposed centre into each open female on a sunny morning before around 10am. One male covers several females; a small dry paintbrush works just as well.
  • Ease off nitrogen once flowering starts, switching to a balanced or potassium-leaning feed so the plant channels energy into fruit rather than leaf.

What to Change Next Season

  • Plant at least two courgettes together for a reliable pollen supply — this zone's own growing notes recommend it for exactly this reason.
  • Space plants a full metre apart in full sun.
  • Keep watering even, and hold back on rich nitrogen feeds once flowers appear.

Black Beauty, Cocozelle, Cocozelle Bush and the Black Coral F1 hybrid are all reliable croppers sourced for this zone — variety choice is rarely the actual cause of a fruitless plant, so work through flowering and feeding first.

Explore the full NZ Sub-Tropical Planting Calendar → for this crop's complete sow-to-harvest timing.