When to plant watermelons in Olsztyn: 9 June – 7 August

In Olsztyn, watermelon: sow for seedlings from 21 April to 10 July; plant into a greenhouse from 19 May to 7 August; plant out into open ground from 9 June to 7 August.

Watermelon in Olsztyn: soil, season and weather

In Olsztyn 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 9 June, 42 days later.

Last spring frost	28 April
Top 7 cm of soil at 18 °C	9 June, 42 days after the last frost
Into an unheated greenhouse	19 May – 7 August; May outside: 7.2 °C at night, 17.7 °C by day; card 18–35 °C
First autumn frost	16 November, 160 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	7 August – 5 October
Days left for picking	101
Daylight	15:45 on 12 May, 16:57 on 9 June
Watering outdoors when fruiting (card)	every 5 days; the driest month, November, has 10 rainy days

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

Watermelon in Olsztyn: care after planting

Planted on 9 June: in the first weeks water every 5 days.

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

9 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 Olsztyn during the watermelon season

No month of the season averages above the watermelon card's 18–35 °C by day; the warmest, August, averages 23.4 °C. Months that stay below 18 °C even by day on average: October (12.7 °C) and November (6.2 °C). Nights average below 18 °C in every month of the season, from 1.9 °C to 13.9 °C.

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
June	22.8	12.5	64	11	17:04
July	22.9	13.9	97	16	16:36
August	23.4	13.9	68	11	14:53
September	19.2	10.6	54	10	12:46
October	12.7	6	64	13	10:39
November	6.2	1.9	43	10	8:37

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Olsztyn, Toruń is 6 days earlier and Gdańsk 6 days later.

City	Distance	Date	Difference
Kaliningrad	103 km	14 June – 5 August	5 days later
Gdańsk	135 km	15 June – 10 August	6 days later
Toruń	151 km	3 June – 3 August	6 days earlier
Gdynia	151 km	7 June – 10 August	2 days earlier
Warsaw	176 km	6 June – 8 August	3 days earlier
Bydgoszcz	179 km	6 June – 3 August	3 days earlier

Where to buy watermelon plants and seeds near Olsztyn

Buy plants ready to set out from 9 June to 7 August (from 19 May to 7 August for an unheated greenhouse); seed for raising your own is sown from 21 April to 10 July. Within 15 km of Olsztyn OpenStreetMap lists 2 garden centres, 1 plant nursery, 5 markets and 2 farm shops (collected 28 October 2026).

Pchli targ "Flumark" — market
Aleja Sybiraków, Olsztyn · Sun 9:00–15:00 · 2 km
Targowisko przy ul. Żurawskiego — market
Mon–Sat 06:00–16:00 · 5 km · zdzit.olsztyn.eu
Targowisko przy ul. Kolejowej — market
Mon–Sat 06:00–16:00 · 1 km · zdzit.olsztyn.eu
Stodoła "Mój Rynek" — market
Sat 09:00–14:00 · 6 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