Nelson gets more sunshine hours than almost anywhere else in New Zealand, and a spring garden here tends to move faster than the rest of the South Island as a result. Frost risk lingers a little longer than the region's sunny reputation suggests though: ground frost averages nearly twenty days in July, and the season doesn't properly clear until November, closer to Waikato's timeline than most people expect from a place known for its climate.
Lettuce, spinach, silverbeet, peas, beetroot, carrots and dwarf beans go in safely from September regardless of frost risk. Tomatoes, capsicums, courgette and sweetcorn are worth holding until November, in line with the region's actual last-frost timing rather than its reputation. Basil in particular is worth starting undercover until then: a late frost is uncommon in Nelson but not impossible, and it's exactly the kind of tender herb that a single cold night wipes out completely.
The real risk once plants are in isn't cold, it's dryness. Nelson's exceptional sunshine hours dry soil out fast, and a new planting can go from healthy to visibly stressed within days if watering doesn't keep pace, especially in the sandier soils common around the Waimea Plains. Mulch beds as soon as they're planted and check soil moisture by hand rather than trusting the weather to keep up.
The real risk once plants are in isn't cold, it's dryness.