When to plant watermelons in Cincinnati: 13 May – 31 July

In Cincinnati, watermelon: sow for seedlings from 25 March to 3 July; plant into a greenhouse from 22 April to 31 July; plant out into open ground from 13 May to 31 July. For plants and seeds, the places nearby include Tewes Farm (farm shop, 12 km) and McGlasson Farms (farm shop, 15 km); addresses and opening hours are below.

Watermelon in Cincinnati: soil, season and weather

In Cincinnati the soil, not frost, sets the date: the last frost is over around 11 April, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 13 May, 32 days later.

Last spring frost	11 April
Top 7 cm of soil at 18 °C	13 May, 32 days after the last frost
Into an unheated greenhouse	22 April – 31 July; April outside: 7 °C at night, 18.1 °C by day; card 18–35 °C
First autumn frost	9 November, 180 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	11 July – 28 September
Days left for picking	121
Daylight	13:12 on 15 April, 14:14 on 13 May
Watering outdoors when fruiting (card)	every 5 days; the driest month, September, has 7 rainy days

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

Watermelon in Cincinnati: care after planting

Planted on 13 May: in the first weeks water every 5 days.

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

13 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 Cincinnati during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, July, averages 30.1 °C. Months that stay below 18 °C even by day on average: November (12 °C). Nights average below 18 °C in May, June and September–November (3–17.8 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	23.3	13	125	15	14:18
June	28.3	17.8	99	12	14:54
July	30.1	20.2	109	13	14:40
August	28.9	19.1	83	12	13:44
September	26.6	16.4	75	7	12:29
October	20.1	10.1	76	10	11:14
November	12	3	76	9	10:04

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Cincinnati, Louisville is 6 days earlier and Columbus 7 days later.

City	Distance	Date	Difference
Dayton	75 km	16 May – 31 July	3 days later
Frankfort	108 km	13 May – 25 July	same day
Lexington	127 km	15 May – 29 July	2 days later
Louisville	146 km	7 May – 2 August	6 days earlier
Indianapolis	159 km	16 May – 28 July	3 days later
Columbus	159 km	20 May – 24 July	7 days later

Where to buy watermelon plants and seeds near Cincinnati

Buy plants ready to set out from 13 May to 31 July (from 22 April to 31 July for an unheated greenhouse); seed for raising your own is sown from 25 March to 3 July. Within 15 km of Cincinnati OpenStreetMap lists 10 garden centres, 6 markets and 2 farm shops (collected 20 October 2026).

Findlay Market — market
Sun 10:00–16:00; Tue–Fri 09:00–18:00; Sat 08:00–18:00 · 2 km · findlaymarket.org
B&D Asian Nepali Market — market
Winton Road 9172, 45231 Cincinnati · 12 km
Tewes Farm — farm shop
Crescent Springs Pike 2801, 41018 · Mon–Tue, Thu–Fri 10:00–18:00; Sat 11:00–15:00 · 12 km · tewesfarm.com
McGlasson Farms — farm shop
River Road 5832 · Mon–Fri 09:00–18:00; Sat–Sun 09:00–17:00 · 15 km · mcglassonfarms.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.

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