When to plant watermelons in Nelson: 20 December – 11 March

In Nelson, watermelon: sow for seedlings from 1 November to 12 February; plant into a greenhouse from 29 November to 11 March; plant out into open ground from 20 December to 11 March. For plants and seeds, the places nearby include The Eyebright Wool Shop (farm supply, 12 km) and Enhance with Plants (garden centre, 13 km); addresses and opening hours are below.

Watermelon in Nelson: soil, season and weather

In Nelson the soil, not frost, sets the date: the last frost is over around 4 August, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 20 December, 138 days later.

Last spring frost	4 August
Top 7 cm of soil at 18 °C	20 December, 138 days after the last frost
Into an unheated greenhouse	29 November – 11 March; November outside: 11.1 °C at night, 19.2 °C by day; card 18–35 °C
First autumn frost	20 June, 183 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	17 February – 9 May
Days left for picking	124
Daylight	14:40 on 22 November, 15:09 on 20 December
Watering outdoors when fruiting (card)	every 5 days; the driest month, January, has 9 rainy days

The same dates in Nelson hold for Cucumber, Bell Pepper, Eggplant, Zucchini and Pumpkin.

Watermelon in Nelson: care after planting

Planted on 20 December: in the first weeks water every 5 days.

Feeding, by the card’s schedule from that day:

20 December — feed: balanced (NPK)

Pests and diseases of watermelon to watch for:

Dates count from the first planting day of the window above; a later planting moves them by as many days.

Weather in Nelson during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, January, averages 22.8 °C. Months that stay below 18 °C even by day on average: May (15.6 °C) and June (13.4 °C). Nights average below 18 °C in every month of the season, from 6.2 °C to 14.4 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
December	21.4	13.2	101	11	15:08
January	22.8	14.4	84	9	14:49
February	22.3	14.1	94	7	13:41
March	20.7	12.6	88	9	12:25
April	18	10.2	96	9	11:00
May	15.6	8.3	127	10	9:51
June	13.4	6.2	110	11	9:13

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

All the nearest cities on our list plant watermelon earlier than Nelson; the closest date is in Timaru, 1 day earlier.

City	Distance	Date	Difference
Blenheim	63 km	11 December – 19 February	9 days earlier
Wellington	125 km	from 17 December	3 days earlier
Palmerston North	221 km	4 December – 11 March	16 days earlier
Christchurch	257 km	1 December – 24 February	19 days earlier
Napier	366 km	from 3 November	47 days earlier
Timaru	384 km	19 December – 23 February	1 day earlier

Where to buy watermelon plants and seeds near Nelson

Buy plants ready to set out from 20 December to 11 March (from 29 November to 11 March for an unheated greenhouse); seed for raising your own is sown from 1 November to 12 February. Within 15 km of Nelson OpenStreetMap lists 1 garden centre, 1 farm-supply shop, 1 plant nursery and 2 markets (collected 20 October 2026).

Kūmānu — plant nursery
2 km · kumanu.co.nz
Enhance with Plants — garden centre
McShane Road 147 · 13 km · facebook.com
The Eyebright Wool Shop — farm supply
McShane Road 40 · Wed–Thu 09:00–05:00 · 12 km · eyebright.co.nz
Nelson Farmers Market — market
Halifax Street 23 · Wed 08:00–13:00 · 0 km · nelsonfarmersmarket.org.nz

Each window starts on the Greenly calendar date and ends on the last day that still leaves the crop’s days to harvest (from its card) before the average first autumn frost, plus six weeks of picking for crops harvested over weeks (tomatoes, peppers, aubergines, cucumbers, courgettes, pumpkins, watermelons, beans) — our rule; earlier in the window is safer.

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