When to plant watermelons in New Haven: 26 May – 3 August

In New Haven, watermelon: sow for seedlings from 7 April to 6 July; plant into a greenhouse from 5 May to 3 August; plant out into open ground from 26 May to 3 August.

Watermelon in New Haven: soil, season and weather

In New Haven the soil, not frost, sets the date: the last frost is over around 6 April, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 26 May, 50 days later.

Last spring frost	6 April
Top 7 cm of soil at 18 °C	26 May, 50 days after the last frost
Into an unheated greenhouse	5 May – 3 August; May outside: 10.5 °C at night, 19.4 °C by day; card 18–35 °C
First autumn frost	12 November, 170 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	24 July – 1 October
Days left for picking	111
Daylight	13:51 on 28 April, 14:49 on 26 May
Watering outdoors when fruiting (card)	every 5 days; the driest month, June, has 10 rainy days

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

Watermelon in New Haven: care after planting

Planted on 26 May: in the first weeks water every 5 days.

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

26 May — 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 New Haven during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, July, averages 28.2 °C. Months that stay below 18 °C even by day on average: November (11.5 °C). Nights average below 18 °C in May, June and September–November (3.5–15.9 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	19.4	10.5	117	13	14:29
June	24.9	15.9	81	10	15:08
July	28.2	20.1	121	12	14:53
August	27.1	19.2	103	12	13:52
September	23.6	15.8	118	10	12:31
October	18.2	10.4	125	11	11:09
November	11.5	3.5	87	8	9:53

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around New Haven, New York is 5 days earlier and Hartford 5 days later.

City	Distance	Date	Difference
Hartford	54 km	31 May – 30 July	5 days later
New York	113 km	21 May – 11 August	5 days earlier
Providence	138 km	31 May – 30 July	5 days later
Worcester (United States)	141 km	31 May – 30 July	5 days later
Albany	164 km	30 May – 28 July	4 days later
Boston	193 km	29 May – 4 August	3 days later

Where to buy watermelon plants and seeds near New Haven

Buy plants ready to set out from 26 May to 3 August (from 5 May to 3 August for an unheated greenhouse); seed for raising your own is sown from 7 April to 6 July. Within 15 km of New Haven OpenStreetMap lists 5 garden centres, 1 plant nursery, 1 market and 3 farm shops (collected 28 October 2026).

HTG Supply — garden centre
9 km
Simon’ Greenhouse — garden centre
11 km
Urbanscapes Native Plant Nursery — plant nursery
2 km
Clover Nook Farm — farm shop
15 km · clovernookfarm.com

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