GreenlyWhen to plant watermelon in Oslo
In Oslo, watermelon: sow seedlings around 13 May for the greenhouse and around 3 June for open ground; plant into a greenhouse around 14 June; plant out into open ground around 5 July.
Last spring frost around 6 May, first autumn frost around 19 October. Frost-free days: 166 days.
The dates follow the Greenly calendar: open ground a week after the last frost once the soil is warm enough for the crop, frost-hardy crops three weeks before it, an unheated greenhouse three weeks earlier, seedlings sown so they are ready on the day. In a cold year allow a week or two more.