When to plant watermelons in Des Moines: 17 May – 18 July

In Des Moines, watermelon: sow for seedlings from 29 March to 20 June; plant into a greenhouse from 26 April to 18 July; plant out into open ground from 17 May to 18 July. For plants and seeds, the places nearby include Earl May Garden Center (garden centre, 10 km) and Iowa Outdoor Products (garden centre, 11 km); addresses and opening hours are below.

Watermelon in Des Moines: soil, season and weather

In Des Moines the soil, not frost, sets the date: the last frost is over around 19 April, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 17 May, 28 days later.

Last spring frost	19 April
Top 7 cm of soil at 18 °C	17 May, 28 days after the last frost
Into an unheated greenhouse	26 April – 18 July; April outside: 5.2 °C at night, 16.6 °C by day; card 18–35 °C
First autumn frost	27 October, 163 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	15 July – 15 September
Days left for picking	104
Daylight	13:29 on 19 April, 14:35 on 17 May
Watering outdoors when fruiting (card)	every 5 days; the driest month, September, has 8 rainy days

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

Watermelon in Des Moines: care after planting

Planted on 17 May: in the first weeks water every 5 days.

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

17 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 Des Moines 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 °C. Nights average below 18 °C in May (11.8 °C), September (16.1 °C) and October (8.6 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	22.6	11.8	125	13	14:31
June	29	18.3	122	11	15:10
July	30	20	92	10	14:55
August	28.9	18.9	86	10	13:53
September	26.4	16.1	84	8	12:31
October	18.5	8.6	94	9	11:09

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Des Moines, Kansas City is 10 days earlier and Sioux Falls 7 days later.

City	Distance	Date	Difference
Cedar Rapids	165 km	20 May – 16 July	3 days later
Omaha	198 km	17 May – 17 July	same day
Davenport	250 km	17 May – 21 July	same day
Lincoln	271 km	11 May – 19 July	6 days earlier
Kansas City	290 km	7 May – 23 July	10 days earlier
Sioux Falls	334 km	24 May – 12 July	7 days later

Where to buy watermelon plants and seeds near Des Moines

Buy plants ready to set out from 17 May to 18 July (from 26 April to 18 July for an unheated greenhouse); seed for raising your own is sown from 29 March to 20 June. Within 15 km of Des Moines OpenStreetMap lists 7 garden centres (collected 20 October 2026).

Earl May Garden Center — garden centre
University Avenue 1845, 50266 · 10 km
Iowa Outdoor Products — garden centre
Whitson Drive 8616, 50322 · 11 km
Canoyer Garden Center — garden centre
Gateway Drive 3355, 50111 Grimes · 15 km
Walmart Garden Center — garden centre
10 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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