Knowing when frost happens in your region is one half of planning around it; knowing which crops can actually take a frost and which can't is the other. This article is about that second half, the which, rather than the when and why, which this site's frost-dates guide covers separately.
Brassicas are the most reliably frost-hardy vegetable group in a New Zealand garden. Kale is the standout example: it survives frost well, and cold weather is often said to improve the flavour of its leaves, which is exactly why it's one of the few vegetables still giving pickings right through winter once established. Broccoli, cauliflower and cabbage are all cool-season crops from the same family, planted through autumn and winter in most regions and generally coping with cold conditions that would finish off a summer crop outright.
Alliums are the other genuinely frost-hardy group. Garlic actually needs a real cold spell over winter to bulb up well, which is why it's traditionally planted on the shortest day, around 21 June, rather than avoiding the coldest part of the year. Leek is similarly hardy and slow-growing, generally planted from late winter into spring and left in the ground for months without frost being a concern.
Garlic actually needs a real cold spell over winter to bulb up well, which is why it's traditionally planted on the shortest day, around 21 June
Peas handle cold well too, sown through the cooler months in most regions as a genuine cool-season crop rather than something that needs frost protection. Broad beans are much the same: a winter-adjacent crop typically sown in autumn that copes with cold conditions through winter while also fixing nitrogen in the soil ahead of spring plantings.
At the other end of the scale, a specific group of summer vegetables are genuinely tender and will die outright at the first frost rather than merely slowing down. Tomatoes, capsicums, cucumbers, zucchini and pumpkin are all frost-tender and are only ever planted once frost risk has passed for the season. Sweetcorn needs the same frost-free conditions to get started. Kumara is the most demanding of the lot, needing around five frost-free months above roughly 17°C to bulk up properly, and it's lifted before the first autumn frosts specifically because the tubers won't survive one.
The practical takeaway is straightforward: brassicas, alliums, peas and broad beans are the crops worth leaving in a winter garden without worry, while tomatoes, capsicums, cucumber, zucchini, pumpkin, sweetcorn and kumara are the ones that need to be fully harvested, or not yet planted, before the cold arrives.