When to plant watermelons in Fort Smith: 1 May – 9 August

In Fort Smith, watermelon: sow for seedlings from 13 March to 12 July; plant into a greenhouse from 10 April to 9 August; plant out into open ground from 1 May to 9 August.

Watermelon in Fort Smith: soil, season and weather

In Fort Smith the soil, not frost, sets the date: the last frost is over around 16 March, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 1 May, 46 days later.

Last spring frost	16 March
Top 7 cm of soil at 18 °C	1 May, 46 days after the last frost
Into an unheated greenhouse	10 April – 9 August; April outside: 10.7 °C at night, 22 °C by day; card 18–35 °C
First autumn frost	18 November, 201 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	29 June – 7 October
Days left for picking	142
Daylight	12:38 on 3 April, 13:36 on 1 May
Watering outdoors when fruiting (card)	every 5 days; the driest month, September, has 6 rainy days

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

Watermelon in Fort Smith: care after planting

Planted on 1 May: in the first weeks water every 5 days.

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

1 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 Fort Smith during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, July, averages 33.5 °C. Months that stay below 18 °C even by day on average: November (17.1 °C). Nights average below 18 °C in May (15.9 °C), October (13.2 °C) and November (6.5 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	26.3	15.9	151	13	14:01
June	31.5	20.8	95	11	14:32
July	33.5	23.2	91	10	14:20
August	32.6	22.4	88	9	13:31
September	30.3	19.4	73	6	12:26
October	24	13.2	113	8	11:20
November	17.1	6.5	91	8	10:19

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Fort Smith, Shreveport is 42 days earlier and Fayetteville 8 days later.

City	Distance	Date	Difference
Fayetteville	78 km	9 May – 1 August	8 days later
Tulsa	169 km	29 April – 8 August	2 days earlier
Joplin	189 km	5 May – 23 July	4 days later
Little Rock	203 km	22 April – 11 August	9 days earlier
Oklahoma City	285 km	15 April – 1 August	16 days earlier
Shreveport	329 km	20 March – 30 August	42 days earlier

Where to buy watermelon plants and seeds near Fort Smith

Buy plants ready to set out from 1 May to 9 August (from 10 April to 9 August for an unheated greenhouse); seed for raising your own is sown from 13 March to 12 July. Within 15 km of Fort Smith OpenStreetMap lists 1 garden centre and 1 plant nursery (collected 28 October 2026).

Home Depot Garden Center — garden centre
4 km
Lafoon's Greenhouse & Nursery — plant nursery
6 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.

Questions