When to plant watermelons in Ann Arbor: 29 May – 27 July

In Ann Arbor, watermelon: sow for seedlings from 10 April to 29 June; plant into a greenhouse from 8 May to 27 July; plant out into open ground from 29 May to 27 July. For plants and seeds, the places nearby include Diuble Equipment Inc. (farm supply, 14 km); addresses and opening hours are below.

Watermelon in Ann Arbor: soil, season and weather

In Ann Arbor the soil, not frost, sets the date: the last frost is over around 28 April, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 29 May, 31 days later.

Last spring frost	28 April
Top 7 cm of soil at 18 °C	29 May, 31 days after the last frost
Into an unheated greenhouse	8 May – 27 July; May outside: 9.7 °C at night, 20.6 °C by day; card 18–35 °C
First autumn frost	5 November, 160 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	27 July – 24 September
Days left for picking	101
Daylight	14:02 on 1 May, 14:59 on 29 May
Watering outdoors when fruiting (card)	every 5 days; the driest month, November, has 10 rainy days

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

Watermelon in Ann Arbor: care after planting

Planted on 29 May: in the first weeks water every 5 days.

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

29 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 Ann Arbor during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, July, averages 28.1 °C. Months that stay below 18 °C even by day on average: October (16.7 °C) and November (8.7 °C). Nights average below 18 °C in May, June and August–November (0.9–17.1 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	20.6	9.7	88	13	14:34
June	26.3	15.5	87	12	15:15
July	28.1	18	92	13	14:59
August	26.9	17.1	87	11	13:56
September	23.7	14.1	73	9	12:32
October	16.7	8	86	12	11:07
November	8.7	0.9	56	10	9:49

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

All the nearest cities on our list plant watermelon earlier than Ann Arbor; the closest date is in Lansing, 1 day earlier.

City	Distance	Date	Difference
Detroit	58 km	27 May – 29 July	2 days earlier
Windsor	60 km	27 May – 29 July	2 days earlier
Toledo (United States)	72 km	24 May – 29 July	5 days earlier
Lansing	82 km	28 May – 24 July	1 day earlier
Grand Rapids	174 km	28 May – 25 July	1 day earlier
Fort Wayne	176 km	21 May – 24 July	8 days earlier

Where to buy watermelon plants and seeds near Ann Arbor

Buy plants ready to set out from 29 May to 27 July (from 8 May to 27 July for an unheated greenhouse); seed for raising your own is sown from 10 April to 29 June. Within 15 km of Ann Arbor OpenStreetMap lists 4 garden centres, 1 farm-supply shop, 2 plant nurseries, 10 markets and 5 farm shops (collected 28 October 2026).

Diuble Equipment Inc. — farm supply
South Parker Road 4365 · 14 km · diubleequipment.com
Ann Arbor Farmers Market — market
Detroit Street 315, 48104 Ann Arbor · Jan–Apr Sat 08:00–15:00; May–Dec Sat, Wed 07:00–15:00 · 1 km · a2farmersmarket.org
Dixboro Farmers' Market — market
Church Road 5221, 48105 Ann Arbor · May–Oct Fri 15:00–18:00 · 9 km · dixborofarmersmarket.org
Dexter Winter Farmers Market — market
Huron River Drive 7643, 48130 Dexter · Nov–Apr Sat[–1], Sat[1] 09:00–13:00 · 13 km · dextermarket.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.

Questions