When to plant watermelons in Tucson: 7 March – 8 September

In Tucson, watermelon: sow for seedlings from 17 January to 11 August; plant into a greenhouse from 14 February to 8 September; plant out into open ground from 7 March to 8 September.

Watermelon in Tucson: soil, season and weather

In Tucson the soil, not frost, sets the date: the last frost is over around 6 February, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 7 March, 29 days later.

Last spring frost	6 February
Top 7 cm of soil at 18 °C	7 March, 29 days after the last frost
Into an unheated greenhouse	14 February – 8 September; February outside: 6 °C at night, 20.9 °C by day; card 18–35 °C
First autumn frost	18 December, 286 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	5 May – 6 November
Days left for picking	227
Daylight	10:48 on 7 February, 11:41 on 7 March
Watering outdoors when fruiting (card)	every 5 days; the driest month, May, has 1 rainy day

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

Watermelon in Tucson: care after planting

Planted on 7 March: in the first weeks water every 5 days.

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

7 March — 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 Tucson during the watermelon season

Days average above the watermelon card's 18–35 °C in June (38.5 °C), July (38 °C) and August (36.9 °C). Nights average below 18 °C in March–May and October–December (6.3–17.2 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
March	24.3	8.9	22	4	11:57
April	29.4	13	5	1	12:57
May	33.1	17.2	3	1	13:48
June	38.5	23.2	10	1	14:15
July	38	25.7	59	8	14:04
August	36.9	24.6	46	7	13:21
September	35	21.8	53	6	12:24
October	30.7	15.9	28	3	11:25
November	24.4	10	23	3	10:31
December	19.6	6.3	35	4	10:03

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around Tucson, Phoenix is 12 days earlier and Flagstaff 66 days later.

City	Distance	Date	Difference
Phoenix	173 km	23 February – 19 September	12 days earlier
Flagstaff	335 km	12 May – 12 July	66 days later
Las Cruces	390 km	5 April – 15 August	29 days later
El Paso	422 km	23 March – 26 August	16 days later
Ciudad Juárez	430 km	23 March – 26 August	16 days later
Albuquerque	508 km	18 April – 31 July	42 days later

Where to buy watermelon plants and seeds near Tucson

Buy plants ready to set out from 7 March to 8 September (from 14 February to 8 September for an unheated greenhouse); seed for raising your own is sown from 17 January to 11 August. Within 15 km of Tucson OpenStreetMap lists 10 garden centres, 1 farm-supply shop and 5 markets (collected 20 October 2026).

Home Depot — garden centre
2 km
Green Things — garden centre
6 km
Walmart Garden Center — garden centre
9 km
The Home Depot — garden centre
10 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