When to plant watermelons in Harrisburg: 25 May – 2 August

In Harrisburg, watermelon: sow for seedlings from 6 April to 5 July; plant into a greenhouse from 4 May to 2 August; plant out into open ground from 25 May to 2 August. For plants and seeds, the places nearby include The Plant Witch (garden centre, 1 km) and Nature's Way Nursery (garden centre, 13 km); addresses and opening hours are below.

Watermelon in Harrisburg: soil, season and weather

In Harrisburg the soil, not frost, sets the date: the last frost is over around 10 April, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 25 May, 45 days later.

Last spring frost	10 April
Top 7 cm of soil at 18 °C	25 May, 45 days after the last frost
Into an unheated greenhouse	4 May – 2 August; May outside: 11.4 °C at night, 22.2 °C by day; card 18–35 °C
First autumn frost	11 November, 170 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	23 July – 30 September
Days left for picking	111
Daylight	13:45 on 27 April, 14:41 on 25 May
Watering outdoors when fruiting (card)	every 5 days; the driest month, November, has 7 rainy days

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

Watermelon in Harrisburg: care after planting

Planted on 25 May: in the first weeks water every 5 days.

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

25 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 Harrisburg during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, July, averages 31 °C. Months that stay below 18 °C even by day on average: November (11.8 °C). Nights average below 18 °C in May, June and September–November (2.9–16.5 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	22.2	11.4	121	15	14:24
June	27.6	16.5	97	13	15:02
July	31	20.1	126	13	14:47
August	29	19	110	12	13:48
September	25.4	15.7	111	10	12:30
October	19.3	9.7	79	9	11:11
November	11.8	2.9	70	7	9:58

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

All the nearest cities on our list plant watermelon earlier than Harrisburg; the closest date is in Hagerstown, 2 days earlier.

City	Distance	Date	Difference
Hagerstown	103 km	23 May – 2 August	2 days earlier
Baltimore	111 km	5 May – 13 August	20 days earlier
Allentown	124 km	23 May – 25 July	2 days earlier
Annapolis	148 km	8 May – 10 August	17 days earlier
Philadelphia	150 km	14 May – 2 August	11 days earlier
Washington, D.C.	152 km	4 May – 7 August	21 days earlier

Where to buy watermelon plants and seeds near Harrisburg

Buy plants ready to set out from 25 May to 2 August (from 4 May to 2 August for an unheated greenhouse); seed for raising your own is sown from 6 April to 5 July. Within 15 km of Harrisburg OpenStreetMap lists 4 garden centres, 4 markets and 3 farm shops (collected 28 October 2026).

Nature's Way Nursery — garden centre
Pleasant Hill Road 1451, 17112 Harrisburg · 13 km · natureswaybonsai.com
The Plant Witch — garden centre
North 3rd Street 11, 17101 Harrisburg · 1 km
Adams-Ricci Farmer's Market — market
Thu 15:00–19:00 · 5 km
Paulus Farm Market — farm shop
South York Street 1216, 17050 Mechanicsburg · 13 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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