When to plant watermelons in Dayton: 16 May – 31 July

In Dayton, watermelon: sow for seedlings from 28 March to 3 July; plant into a greenhouse from 25 April to 31 July; plant out into open ground from 16 May to 31 July. For plants and seeds, the places nearby include Mission of Mary Roadside Market (farm shop, 2 km) and Gardening Haven (garden centre, 6 km); addresses and opening hours are below.

Watermelon in Dayton: soil, season and weather

In Dayton the soil, not frost, sets the date: the last frost is over around 17 April, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 16 May, 29 days later.

Last spring frost	17 April
Top 7 cm of soil at 18 °C	16 May, 29 days after the last frost
Into an unheated greenhouse	25 April – 31 July; April outside: 6.2 °C at night, 17.2 °C by day; card 18–35 °C
First autumn frost	9 November, 177 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	14 July – 28 September
Days left for picking	118
Daylight	13:21 on 18 April, 14:23 on 16 May
Watering outdoors when fruiting (card)	every 5 days; the driest month, September, has 8 rainy days

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

Watermelon in Dayton: care after planting

Planted on 16 May: in the first weeks water every 5 days.

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

16 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 Dayton during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, July, averages 29.3 °C. Months that stay below 18 °C even by day on average: November (11.2 °C). Nights average below 18 °C in May, June and September–November (2.5–17.3 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	22.6	12.4	125	16	14:21
June	27.6	17.3	102	12	14:58
July	29.3	19.7	104	14	14:44
August	28.1	18.5	84	11	13:46
September	26	15.7	74	8	12:30
October	19.3	9.6	77	9	11:12
November	11.2	2.5	75	8	10:01

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Dayton, Cincinnati is 3 days earlier and Fort Wayne 5 days later.

City	Distance	Date	Difference
Cincinnati	75 km	13 May – 31 July	3 days earlier
Columbus	104 km	20 May – 24 July	4 days later
Fort Wayne	167 km	21 May – 24 July	5 days later
Indianapolis	168 km	16 May – 28 July	same day
Frankfort	183 km	13 May – 25 July	3 days earlier
Lexington	198 km	15 May – 29 July	1 day earlier

Where to buy watermelon plants and seeds near Dayton

Buy plants ready to set out from 16 May to 31 July (from 25 April to 31 July for an unheated greenhouse); seed for raising your own is sown from 28 March to 3 July. Within 15 km of Dayton OpenStreetMap lists 9 garden centres, 1 market and 2 farm shops (collected 29 October 2026).

Gardening Haven — garden centre
Woodman Drive 465, 45431 Dayton · Mon–Sat 10:00–19:00 · 6 km · gardeninghaven.com
Siebenthaler's — garden centre
beaver valley rd 2074, 45434 Beavercreek · Mon–Sat 09:00–17:00; Sun 11:00–17:00 · 15 km · share.google
Mission of Mary Roadside Market — farm shop
Xenia Avenue, 45410 Dayton · Jun–Oct Fri 10:00–13:00 · 2 km
Rural king — farm shop
Old Troy Pike, 45424 · 12 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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