GreenlyWhen to plant watermelon in Johannesburg
In Johannesburg, watermelon: sow seedlings around 15 July for the greenhouse and around 5 August for open ground; plant into a greenhouse around 16 August; plant out into open ground around 6 September.
Last spring frost around 4 August, first autumn frost around 5 June. Frost-free days: 305 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.