When to plant watermelons in Cambridge: 17 June – 15 August

In Cambridge, watermelon: sow for seedlings from 29 April to 18 July; plant into a greenhouse from 27 May to 15 August; plant out into open ground from 17 June to 15 August. For plants and seeds, the places nearby include Coton Orchard Garden Centre (garden centre, 4 km) and Darwin Nurseries & Farm Shop (garden centre, 5 km); addresses and opening hours are below.

Watermelon in Cambridge: soil, season and weather

In Cambridge the soil, not frost, sets the date: the last frost is over around 3 April, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 17 June, 75 days later.

Last spring frost	3 April
Top 7 cm of soil at 18 °C	17 June, 75 days after the last frost
Into an unheated greenhouse	27 May – 15 August; May outside: 8.2 °C at night, 17.1 °C by day; card 18–35 °C
First autumn frost	24 November, 160 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	15 August – 13 October
Days left for picking	101
Daylight	15:56 on 20 May, 16:45 on 17 June
Watering outdoors when fruiting (card)	every 5 days; the driest month, August, has 10 rainy days

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

Watermelon in Cambridge: care after planting

Planted on 17 June: in the first weeks water every 5 days.

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

17 June — 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 Cambridge during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, July, averages 22.5 °C. Months that stay below 18 °C even by day on average: October (15.3 °C) and November (10.6 °C). Nights average below 18 °C in every month of the season, from 4.9 °C to 13.8 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
June	20.6	11.7	57	10	16:44
July	22.5	13.8	66	12	16:19
August	22.5	13.6	50	10	14:44
September	19.8	11.4	62	10	12:43
October	15.3	8.6	71	11	10:43
November	10.6	4.9	60	11	8:49

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Cambridge, London is 5 days earlier and Norwich 10 days later.

City	Distance	Date	Difference
Ipswich	73 km	14 June – 20 August	3 days earlier
London	79 km	12 June – 14 August	5 days earlier
Norwich	93 km	27 June – 19 August	10 days later
Leicester	98 km	21 June – 10 August	4 days later
Oxford	107 km	23 June – 14 August	6 days later
Coventry	113 km	21 June – 8 August	4 days later

Where to buy watermelon plants and seeds near Cambridge

Buy plants ready to set out from 17 June to 15 August (from 27 May to 15 August for an unheated greenhouse); seed for raising your own is sown from 29 April to 18 July. Within 15 km of Cambridge OpenStreetMap lists 11 garden centres, 1 farm-supply shop, 2 markets and 7 farm shops (collected 20 October 2026).

Phillimore Garden Centre — garden centre
Cambridge Road, SG8 6EY Royston · Mon–Sat 09:00–17:00; Sun 10:00–16:00; public holidays 10:00–16:00 · 13 km
Arrington Garden Centre & Cafe — garden centre
Ermine Wat, SG8 0AG Royston · 15 km · arringtongardencentre.co.uk
Coton Orchard Garden Centre — garden centre
Cambridge Road, CB23 7PJ · 4 km · bluediamond.gg
Darwin Nurseries & Farm Shop — garden centre
Newmarket Road, CB1 9AT · 5 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.

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