When to plant watermelons in Blenheim: 11 December – 19 February

In Blenheim, watermelon: sow for seedlings from 23 October to 22 January; plant into a greenhouse from 20 November to 19 February; plant out into open ground from 11 December to 19 February. For plants and seeds, the places nearby include Golden Mile Produce (farm shop, 6 km); addresses and opening hours are below.

Watermelon in Blenheim: soil, season and weather

In Blenheim the soil, not frost, sets the date: the last frost is over around 10 August, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 11 December, 123 days later.

Last spring frost	10 August
Top 7 cm of soil at 18 °C	11 December, 123 days after the last frost
Into an unheated greenhouse	20 November – 19 February; November outside: 11 °C at night, 19.9 °C by day; card 18–35 °C
First autumn frost	30 May, 171 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	8 February – 18 April
Days left for picking	112
Daylight	14:23 on 13 November, 15:07 on 11 December
Watering outdoors when fruiting (card)	every 5 days; the driest month, January, has 7 rainy days

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

Watermelon in Blenheim: care after planting

Planted on 11 December: in the first weeks water every 5 days.

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

11 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 Blenheim during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, January, averages 23.3 °C. Months that stay below 18 °C even by day on average: May (15.7 °C). Nights average below 18 °C in every month of the season, from 8.2 °C to 14 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
December	21.8	12.9	78	10	15:09
January	23.3	14	50	7	14:51
February	23	13.8	65	6	13:42
March	21.1	12.3	61	8	12:25
April	18.3	10.2	75	7	11:00
May	15.7	8.2	72	9	9:50

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Blenheim, Napier is 38 days earlier and Nelson 9 days later.

City	Distance	Date	Difference
Nelson	63 km	20 December – 11 March	9 days later
Wellington	73 km	from 17 December	6 days later
Palmerston North	189 km	4 December – 11 March	7 days earlier
Christchurch	249 km	1 December – 24 February	10 days earlier
Napier	336 km	from 3 November	38 days earlier
Timaru	389 km	19 December – 23 February	8 days later

Where to buy watermelon plants and seeds near Blenheim

Buy plants ready to set out from 11 December to 19 February (from 20 November to 19 February for an unheated greenhouse); seed for raising your own is sown from 23 October to 22 January. Within 15 km of Blenheim OpenStreetMap lists 1 market and 1 farm shop (collected 28 October 2026).

Marlborough Farmers' Market — market
Maxwell Road · Sun 09:00–12:00 · 2 km
Golden Mile Produce — farm shop
Sat 14:00–18:00 · 6 km

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.

Questions