When to plant watermelons in Cedar Rapids: 20 May – 16 July

In Cedar Rapids, watermelon: sow for seedlings from 1 April to 18 June; plant into a greenhouse from 29 April to 16 July; plant out into open ground from 20 May to 16 July. For plants and seeds, the places nearby include Earl May Garden Center (garden centre, 9 km) and MHM Ranch (farm shop, 14 km); addresses and opening hours are below.

Watermelon in Cedar Rapids: soil, season and weather

In Cedar Rapids the soil, not frost, sets the date: the last frost is over around 22 April, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 20 May, 28 days later.

Last spring frost	22 April
Top 7 cm of soil at 18 °C	20 May, 28 days after the last frost
Into an unheated greenhouse	29 April – 16 July; April outside: 4.4 °C at night, 15.4 °C by day; card 18–35 °C
First autumn frost	25 October, 158 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	18 July – 13 September
Days left for picking	99
Daylight	13:38 on 22 April, 14:42 on 20 May
Watering outdoors when fruiting (card)	every 5 days; the driest month, September, has 8 rainy days

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

Watermelon in Cedar Rapids: care after planting

Planted on 20 May: in the first weeks water every 5 days.

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

20 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 Cedar Rapids during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, July, averages 28.6 °C. Months that stay below 18 °C even by day on average: October (17.6 °C). Nights average below 18 °C in May, June and September, October (8.1–17.5 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	21.9	11.1	115	13	14:33
June	28	17.5	114	10	15:13
July	28.6	19.2	84	11	14:57
August	27.6	18.1	91	10	13:54
September	25.2	15.2	81	8	12:32
October	17.6	8.1	97	10	11:08

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Cedar Rapids, Springfield is 5 days earlier and Rockford 8 days later.

City	Distance	Date	Difference
Davenport	100 km	17 May – 21 July	3 days earlier
Des Moines	165 km	17 May – 18 July	3 days earlier
Rockford	219 km	28 May – 19 July	8 days later
Madison	224 km	28 May – 18 July	8 days later
Peoria	224 km	18 May – 22 July	2 days earlier
Springfield	295 km	15 May – 23 July	5 days earlier

Where to buy watermelon plants and seeds near Cedar Rapids

Buy plants ready to set out from 20 May to 16 July (from 29 April to 16 July for an unheated greenhouse); seed for raising your own is sown from 1 April to 18 June. Within 15 km of Cedar Rapids OpenStreetMap lists 5 garden centres, 3 markets and 1 farm shop (collected 28 October 2026).

Karibu Market — market
3rd Avenue Southeast 707, 52401 Cedar Rapids · 3 km · karibumarketcedarrapids.com
Cedar Rapids African and Oriental Market — market
Wiley Boulevard Southwest 2000, 52404 Cedar Rapids · 4 km
MHM Ranch — farm shop
East Bertram Road 1443, 52403 Cedar Rapids · 14 km
Earl May Garden Center — garden centre
Northland Avenue Northeast 5155, 52402 Cedar Rapids · Mon–Sat 09:00–18:00; Sun 12:00–17:00 · 9 km · earlmay.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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