GreenlyWhen to plant watermelon in Phoenix
In Phoenix, watermelon: sow seedlings around 1 January for the greenhouse and around 22 January for open ground; plant into a greenhouse around 2 February; plant out into open ground around 23 February.
Last spring frost around 4 February, first autumn frost around 29 December. Frost-free days: 328 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.