Courgette is frost-tender, and that costs this zone a real month of harvest: cool/mountain's first autumn frost typically lands in March, a full month ahead of a milder garden's April, so the picking season closes correspondingly sooner even though sowing starts on the same November calendar everywhere. Nine varieties are sourced for this zone across Kings Seeds NZ and Koanga Institute — worth choosing with that shorter finish in mind rather than assuming any variety here behaves the same as it would further north.
The Comparison
| Variety | Supplier | Fruit | Notable for |
|---|---|---|---|
| Black Coral F1 | Kings Seeds NZ | Almost-black, glossy, cylindrical | Open bush habit improves airflow, which reduces powdery mildew risk |
| Gold Rush F1 | Kings Seeds NZ | Golden-yellow, cylindrical | Long harvest window, upright habit for easy picking |
| Black Beauty | Kings Seeds NZ | Dark-green, cylindrical | Highly uniform fruit, open habit for easy harvest |
| Summer Gold | Kings Seeds NZ | Bright yellow, slender | Best picked young; regular picking encourages more fruit to set |
| Cocozelle | Kings Seeds NZ | Pale-green with dark stripes | Classic striped Italian type, best harvested young |
| Cocozelle Bush | Koanga Institute | Green, striped, bush form | Open-pollinated striped type; male flowers also edible |
| Costata Romanesco | Kings Seeds NZ | Grey-green, ribbed | Lower yield than hybrids but stronger flavour; good male-flower producer |
| Long Green Bush Marrow | Koanga Institute | Long, green | Dual-purpose — good picked young as courgette or left to full marrow size |
| Squash Crookneck | Koanga Institute | Yellow, warty when mature | Not a true courgette — a related summer squash, compact bush, very heavy cropper |
Picking for a Shorter Season
With roughly a month less on the vine than a milder zone gets, Gold Rush F1's long harvest window earns extra weight here — it's the one variety in this set whose own description specifically calls out an extended cropping period, which helps offset the earlier close rather than compounding it. Summer Gold's advice to pick young and pick often is worth leaning into as well: the more consistently a plant is harvested, the more fruit it sets in the time it has, and that trade-off matters more against a firm autumn cutoff than it does where the season simply tapers.
The Hybrids
Kings Seeds NZ's Black Coral F1 and Gold Rush F1 are the two hybrids on this list, and both are bred for an open bush shape that's easier to pick into. Black Coral F1's open growth also gets airflow credit for cutting the risk of powdery mildew — genuinely useful in a crop that's often grown densely; see Powdery Mildew on NZ Courgettes and Pumpkins if you've already had it show up. Black Beauty and Summer Gold carry the same open-habit, uniform-fruit traits without being named as F1s specifically.
The Heirloom, Open-Pollinated Types
Koanga Institute's three entries — Cocozelle Bush, Long Green Bush Marrow, and Squash Crookneck — are all heirloom, open-pollinated seed. Koanga sources their garlic range the same way, though that crop goes into the ground here for a completely different, cold-driven reason than courgette does. Open-pollinated seed is worth saving from your own strongest plants season to season, something none of the F1 hybrids above can offer reliably.
Cocozelle Bush is close kin to Kings Seeds NZ's plain Cocozelle — same striped fruit, a different breeding line — but Koanga's notes add that its male flowers are edible too, a detail the Kings Seeds listing skips. Costata Romanesco gives up some yield for flavour: its own description says plainly that it crops less than the hybrids here but tastes better, on a larger, leafier plant that also throws unusually many male blossoms for cooking. Long Green Bush Marrow is the genuine dual-purpose pick — good pulled young as a courgette, and one of the few here that stays worth eating if you let it run on to full marrow size instead.
Strictly Speaking, Not a Courgette
Squash Crookneck stands apart from the other eight for a reason the supplier's own copy spells out — it rates its flavour against "all other courgettes," language that treats it as a separate category rather than one more variety in the line-up. It's a swan-necked yellow summer squash, best sautéed young; left longer, the skin colours golden-orange, toughens, and turns warty. The plant stays compact and crops hard, and picking it regularly keeps it going for the length of the season.
Planting for This Zone
Sowing itself doesn't shift for this zone — November to February, after the last frost, the same as anywhere else in NZ — but harvest runs January to March here rather than into April, a direct result of that earlier autumn frost closing things out sooner. Space plants a full metre apart, and always grow at least two: courgette needs separate male and female flowers pollinated across plants, and a single specimen is more prone to flowering without setting fruit. Two dedicated troubleshooting guides cover that gap in more depth than fits here — poor fruit set and flowers dropping before they open, both written for this zone specifically.
For the Koanga varieties specifically, don't transplant on the calendar alone — their notes are consistent that seedlings should go out once soil temperature reaches 15–16°C, pricked out at 6cm spacing in the tray first. In a zone that's slower to warm in spring, that soil-temperature check matters more than in a garden where the ground's already reliably warm by the time the sowing window opens.
Slotting courgette into the rest of your summer beds? See the full NZ Cool/Mountain Planting Calendar →.