When to plant watermelons in Dover: 11 May – 17 August

In Dover, watermelon: sow for seedlings from 23 March to 20 July; plant into a greenhouse from 20 April to 17 August; plant out into open ground from 11 May to 17 August. For plants and seeds, the places nearby include Lancaster County Farmers Market (farm shop, 1 km) and Tractor Supply Co (farm shop, 7 km); addresses and opening hours are below.

Watermelon in Dover: soil, season and weather

In Dover the soil, not frost, sets the date: the last frost is over around 28 March, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 11 May, 44 days later.

Last spring frost	28 March
Top 7 cm of soil at 18 °C	11 May, 44 days after the last frost
Into an unheated greenhouse	20 April – 17 August; April outside: 8.6 °C at night, 17.7 °C by day; card 18–35 °C
First autumn frost	26 November, 199 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	9 July – 15 October
Days left for picking	140
Daylight	13:08 on 13 April, 14:11 on 11 May
Watering outdoors when fruiting (card)	every 5 days; the driest month, November, has 7 rainy days

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

Watermelon in Dover: care after planting

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

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

11 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 Dover during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, July, averages 29.9 °C. Months that stay below 18 °C even by day on average: November (13.6 °C). Nights average below 18 °C in May (13.7 °C), October (12.6 °C) and November (5.9 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	22	13.7	133	13	14:18
June	27.2	19	101	11	14:54
July	29.9	22.5	167	14	14:40
August	28.5	21.4	134	13	13:44
September	25.5	18.5	127	11	12:29
October	20.3	12.6	96	8	11:13
November	13.6	5.9	72	7	10:03

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Dover, Washington, D.C. is 7 days earlier and Trenton 10 days later.

City	Distance	Date	Difference
Annapolis	87 km	8 May – 10 August	3 days earlier
Philadelphia	93 km	14 May – 2 August	3 days later
Baltimore	95 km	5 May – 13 August	6 days earlier
Atlantic City	97 km	5 May – 13 August	6 days earlier
Washington, D.C.	134 km	4 May – 7 August	7 days earlier
Trenton	134 km	21 May – 3 August	10 days later

Where to buy watermelon plants and seeds near Dover

Buy plants ready to set out from 11 May to 17 August (from 20 April to 17 August for an unheated greenhouse); seed for raising your own is sown from 23 March to 20 July. Within 15 km of Dover OpenStreetMap lists 1 market and 2 farm shops (collected 28 October 2026).

Spence's Bazaar — market
South New Street 550, 19904 · Tue, Fri 07:30–17:00; Sat 07:30–15:00 · 1 km
Lancaster County Farmers Market — farm shop
South New Street 544, 19904 · Tue, Fri 07:00–17:00; Sat 07:00–15:00 · 1 km
Tractor Supply Co — farm shop
South Dupont Highway 4089, 19901 · Mon–Sat 08:00–20:00; Sun 09:00–19:00 · 7 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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