When to plant watermelons in St. John's: 14 July – 1 August

In St. John's, watermelon: sow for seedlings from 26 May to 4 July; plant into a greenhouse from 23 June to 1 August; plant out into open ground from 14 July to 1 August. For plants and seeds, the places nearby include The Seed Company (garden centre, 1 km); addresses and opening hours are below.

Watermelon in St. John's: soil, season and weather

In St. John's the soil, not frost, sets the date: the last frost is over around 19 May, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 14 July, 56 days later.

Last spring frost	19 May
Top 7 cm of soil at 18 °C	14 July, 56 days after the last frost
Into an unheated greenhouse	23 June – 1 August; June outside: 7.8 °C at night, 15 °C by day; card 18–35 °C
First autumn frost	10 November, 119 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	11 September – 29 September
Days left for picking	60
Daylight	15:58 on 16 June, 15:39 on 14 July
Watering outdoors when fruiting (card)	every 5 days; the driest month, August, has 12 rainy days

The same dates in St. John's hold for Cucumber, Bell Pepper, Eggplant, Zucchini and Pumpkin.

Watermelon in St. John's: care after planting

Planted on 14 July: in the first weeks water every 5 days.

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

14 July — 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 St. John's during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, August, averages 20.3 °C. Months that stay below 18 °C even by day on average: September (16.6 °C), October (11.6 °C) and November (7.2 °C). Nights average below 18 °C in every month of the season, from 1.8 °C to 13.9 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
July	19.7	12.9	98	12	15:37
August	20.3	13.9	93	12	14:19
September	16.6	10.8	111	11	12:38
October	11.6	6.3	97	12	10:56
November	7.2	1.8	179	15	9:20

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

All the nearest cities on our list plant watermelon earlier than St. John's; the closest date is in Halifax, 11 days earlier.

City	Distance	Date	Difference
Charlottetown	805 km	27 June – 24 July	17 days earlier
Halifax	897 km	3 July – 31 July	11 days earlier
Moncton	933 km	26 June – 26 July	18 days earlier
Fredericton	1,077 km	28 June – 19 July	16 days earlier
Bangor	1,268 km	25 June – 25 July	19 days earlier
Augusta	1,365 km	22 June – 25 July	22 days earlier

Where to buy watermelon plants and seeds near St. John's

Buy plants ready to set out from 14 July to 1 August (from 23 June to 1 August for an unheated greenhouse); seed for raising your own is sown from 26 May to 4 July. Within 15 km of St. John's OpenStreetMap lists 3 garden centres and 2 markets (collected 20 October 2026).

Traverse Gardens — garden centre
13 km
The Seed Company — garden centre
King's Road 88, A1C 6L7 St. John's · 1 km · theseedcompany.ca
St. John's Farmer's Market — market
Freshwater Road 245, St. John's · 2 km
Lester's Farm Market — market
"seasonal" · 7 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.

Questions