USDA Hardiness Zone 9a
Frost Dates for 78665 — Round Rock, Texas
Averages from Johnson City 2n, Tx US, the nearest reporting station, 6.3 miles away.
Plant tender crops after March 22, and expect the first autumn freeze around November 9. That leaves about 235 frost-free days.
- Last spring frost
- March 22
- First fall frost
- November 9
- Growing season
- 235 days
- Hardiness zone
- 9a
50% probability
50% probability
frost-free
20 to 25°F annual low
Planting calendar for 78665
| When | What to do |
|---|---|
| January 11 – January 25 | Start peppers and aubergines indoors They need eight to ten weeks under lights before they can go out. |
| January 25 – February 8 | Start tomatoes indoors Six to eight weeks gives a transplant big enough to set fruit early. |
| February 22 – March 8 | Sow peas, spinach, lettuce, radish outdoors These tolerate light frost and prefer to germinate in cool soil. |
| March 22 onward | Transplant tomatoes, peppers, basil, squash, cucumbers The average last freeze has passed — still watch the actual forecast. |
| by August 17 | Sow the autumn crop of carrots, beets and brassicas They need about twelve weeks to size up before growth stops. |
| by October 26 | Harvest tender crops, or be ready to cover them A first freeze two weeks early is well within normal variation. |
| November 9 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 March 22 to put tender plants — tomatoes, peppers, basil, squash — in the ground. That is the date by which half of years in Round Rock, Texas are past their last freeze. Harvest before November 9, which leaves roughly 235 frost-free days.
ZIP 78665 sits in USDA hardiness zone 9a, meaning the average coldest night of the year falls between 20 to 25°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.