When to plant watermelons in Hamilton: 1 June – 29 July

In Hamilton, watermelon: sow for seedlings from 13 April to 1 July; plant into a greenhouse from 11 May to 29 July; plant out into open ground from 1 June to 29 July. For plants and seeds, the places nearby include Northland Nurseries (garden centre, 15 km); addresses and opening hours are below.

Watermelon in Hamilton: soil, season and weather

In Hamilton 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 1 June, 43 days later.

Last spring frost	19 April
Top 7 cm of soil at 18 °C	1 June, 43 days after the last frost
Into an unheated greenhouse	11 May – 29 July; May outside: 9.4 °C at night, 18.8 °C by day; card 18–35 °C
First autumn frost	7 November, 159 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	30 July – 26 September
Days left for picking	100
Daylight	14:14 on 4 May, 15:10 on 1 June
Watering outdoors when fruiting (card)	every 5 days; the driest month, September, has 9 rainy days

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

Watermelon in Hamilton: care after planting

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

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

1 June — 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 Hamilton 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 °C. Months that stay below 18 °C even by day on average: October (16.6 °C) and November (9.1 °C). Nights average below 18 °C in June and September–November (2.4–15.6 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
June	24.8	15.6	71	10	15:22
July	28	18.8	86	11	15:05
August	26.6	18.5	69	11	13:59
September	23.2	15.3	59	9	12:33
October	16.6	9.4	85	11	11:05
November	9.1	2.4	61	10	9:44

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Hamilton, Toronto is 3 days earlier and Rochester 1 day later.

City	Distance	Date	Difference
Kitchener	57 km	31 May – 17 July	1 day earlier
Toronto	58 km	29 May – 21 July	3 days earlier
Buffalo	88 km	29 May – 1 August	3 days earlier
London (Canada)	116 km	29 May – 29 July	3 days earlier
Erie	126 km	30 May – 10 August	2 days earlier
Rochester	181 km	2 June – 3 August	1 day later

Where to buy watermelon plants and seeds near Hamilton

Buy plants ready to set out from 1 June to 29 July (from 11 May to 29 July for an unheated greenhouse); seed for raising your own is sown from 13 April to 1 July. Within 15 km of Hamilton OpenStreetMap lists 10 garden centres, 5 markets and 4 farm shops (collected 20 October 2026).

Northland Nurseries — garden centre
Mon–Sun, public holidays 09:00–17:00 · 15 km
Ottawa Street Farmers' Market — market
Britannia Avenue 3, L8H 3Z5 Hamilton · Sat 08:00–14:00 · 3 km · ottawastreetfarmers.com
Hamilton Farmer's Market — market
York Boulevard 35 · Tue–Fri 09:00–16:00; Wed closed; Sat 08:00–16:00 · 2 km · hamiltonfarmersmarket.ca
M&M Food Market — market
Upper Wentworth Street 970 · Mon–Fri 09:00–20:00; Sat 09:00–19:00; Sun 10:00–18:00 · 4 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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