When to plant watermelons in Joplin: 5 May – 23 July

In Joplin, watermelon: sow for seedlings from 17 March to 25 June; plant into a greenhouse from 14 April to 23 July; plant out into open ground from 5 May to 23 July.

Watermelon in Joplin: soil, season and weather

In Joplin the soil, not frost, sets the date: the last frost is over around 30 March, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 5 May, 36 days later.

Last spring frost	30 March
Top 7 cm of soil at 18 °C	5 May, 36 days after the last frost
Into an unheated greenhouse	14 April – 23 July; April outside: 9.3 °C at night, 20.5 °C by day; card 18–35 °C
First autumn frost	1 November, 180 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	3 July – 20 September
Days left for picking	121
Daylight	12:49 on 7 April, 13:50 on 5 May
Watering outdoors when fruiting (card)	every 5 days; the driest month, November, has 8 rainy days

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

Watermelon in Joplin: care after planting

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

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

5 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 Joplin during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, July, averages 32.4 °C. Months that stay below 18 °C even by day on average: November (15.2 °C). Nights average below 18 °C in May (14.5 °C), October (11.8 °C) and November (5.3 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	24.7	14.5	178	14	14:08
June	30.6	19.8	96	9	14:42
July	32.4	22	84	10	14:29
August	31.4	21.1	97	11	13:37
September	28.9	18.2	69	7	12:27
October	22.2	11.8	106	9	11:17
November	15.2	5.3	61	8	10:12

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Joplin, Tulsa is 6 days earlier and Fayetteville 4 days later.

City	Distance	Date	Difference
Fayetteville	118 km	9 May – 1 August	4 days later
Tulsa	168 km	29 April – 8 August	6 days earlier
Fort Smith	189 km	1 May – 9 August	4 days earlier
Kansas City	225 km	7 May – 23 July	2 days later
Topeka	241 km	6 May – 20 July	1 day later
Wichita	259 km	2 May – 21 July	3 days earlier

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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