When to plant watermelons in San Antonio: 28 February – 26 August

In San Antonio, watermelon: sow for seedlings from 10 January to 29 July; plant into a greenhouse from 7 February to 26 August; plant out into open ground from 28 February to 26 August. For plants and seeds, the places nearby include San Antonio Garden Center (garden centre, 5 km) and Walmart Garden Center (garden centre, 8 km); addresses and opening hours are below.

Watermelon in San Antonio: soil, season and weather

In San Antonio the soil, not frost, sets the date: the last frost is over around 10 February, but the top 7 cm of soil reaches 18 °C — the minimum on the watermelon card — only around 28 February, 18 days later.

Last spring frost	10 February
Top 7 cm of soil at 18 °C	28 February, 18 days after the last frost
Into an unheated greenhouse	7 February – 26 August; February outside: 8.8 °C at night, 20.4 °C by day; card 18–35 °C
First autumn frost	5 December, 280 days after the start
Days in the bed to the first harvest (card)	59
First harvest, if planted in this window	28 April – 24 October
Days left for picking	221
Daylight	10:46 on 31 January, 11:31 on 28 February
Watering outdoors when fruiting (card)	every 5 days; the driest month, December, has 8 rainy days

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

Watermelon in San Antonio: care after planting

Planted on 28 February: in the first weeks water every 5 days.

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

28 February — 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 San Antonio during the watermelon season

Days average above the watermelon card's 18–35 °C in July (35.1 °C) and August (35.5 °C). Nights average below 18 °C in February–April and October–December (8.8–17.7 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
February	20.4	8.8	59	8	11:09
March	25.2	13.5	65	11	11:58
April	27.8	16.3	94	12	12:52
May	30.7	20.1	167	16	13:37
June	34	23.2	80	12	14:01
July	35.1	24.3	85	8	13:52
August	35.5	24.7	88	9	13:13
September	32.4	22.4	107	9	12:22
October	28.5	17.7	80	8	11:30
November	22.4	12.5	67	9	10:42
December	19.3	9.3	57	8	10:16

ERA5 2016–2025, Open-Meteo

Watermelon in nearby cities

Around San Antonio, Reynosa is 30 days earlier and Fort Worth 22 days later.

City	Distance	Date	Difference
Austin	119 km	3 March – 3 September	3 days later
Corpus Christi	215 km	5 February – 13 September	23 days earlier
Nuevo Laredo	238 km	3 February – 13 September	25 days earlier
Houston	304 km	24 February – 18 August	4 days earlier
Reynosa	371 km	29 January – 13 September	30 days earlier
Fort Worth	385 km	22 March – 21 August	22 days later

Where to buy watermelon plants and seeds near San Antonio

Buy plants ready to set out from 28 February to 26 August (from 7 February to 26 August for an unheated greenhouse); seed for raising your own is sown from 10 January to 29 July. Within 15 km of San Antonio OpenStreetMap lists 3 garden centres, 4 markets and 1 farm shop (collected 20 October 2026).

San Antonio Garden Center — garden centre
North New Braunfels Avenue 3310, 78209 San Antonio · Mon–Fri 09:00–15:00 · 5 km · sanantoniogardencenter.org
Walmart Garden Center — garden centre
Southeast Military Drive 1200, 78214 San Antonio · 8 km · walmart.com
Walmart Garden Center — garden centre
Southeast Military Drive 3302, 78223 San Antonio · 06:00–23:00 · 10 km
Chicho Boys Fruit Market — market
South Laredo Street 1631, 78207 · Sun 10:00–18:00, Mon–Sat 09:00–19:00 · 2 km · chichoboys.com

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