USDA Hardiness Zone 9b
Frost Dates for 78582 — Rio Grande City, Texas
Averages from Rio Grande City, Tx US, the nearest reporting station, 8.7 miles away.
Plant tender crops after January 31, and expect the first autumn freeze around December 17. That leaves about 321 frost-free days.
- Last spring frost
- January 31
- First fall frost
- December 17
- Growing season
- 321 days
- Hardiness zone
- 9b
50% probability
50% probability
frost-free
25 to 30°F annual low
Planting calendar for 78582
| When | What to do |
|---|---|
| November 22 – December 6 | Start peppers and aubergines indoors They need eight to ten weeks under lights before they can go out. |
| December 6 – December 20 | Start tomatoes indoors Six to eight weeks gives a transplant big enough to set fruit early. |
| January 3 – January 17 | Sow peas, spinach, lettuce, radish outdoors These tolerate light frost and prefer to germinate in cool soil. |
| January 31 onward | Transplant tomatoes, peppers, basil, squash, cucumbers The average last freeze has passed — still watch the actual forecast. |
| by September 24 | Sow the autumn crop of carrots, beets and brassicas They need about twelve weeks to size up before growth stops. |
| by December 3 | Harvest tender crops, or be ready to cover them A first freeze two weeks early is well within normal variation. |
| December 17 onward | Plant garlic, mulch beds, lift tender bulbs Garlic wants a cold spell; bare soil loses structure over winter. |
What these dates mean
Wait until after January 31 to put tender plants — tomatoes, peppers, basil, squash — in the ground. That is the date by which half of years in Rio Grande City, Texas are past their last freeze. Harvest before December 17, which leaves roughly 321 frost-free days.
ZIP 78582 sits in USDA hardiness zone 9b, meaning the average coldest night of the year falls between 25 to 30°F. Zone decides what survives the winter; frost dates decide when to plant each spring. They are different questions, and a plant can pass one and fail the other.
These are thirty-year NOAA averages for 1991–2020, not a forecast. Any individual year can frost two to three weeks either side of these dates, so check the actual forecast before planting out.