Gardening in Austin-Round Rock-San Marcos, TX
This metro spans USDA zones 8b to 9a, so there is no single zone for Austin-Round Rock-San Marcos, TX and anyone who gives you one is rounding. 88% of its ZIP codes are zone 9a; the rest are not.
Which zone you are in depends where you are
Austin-Round Rock-San Marcos, TX covers 2 hardiness zones. A guide that gives the metro one zone has picked whichever is largest and rounded everyone else into it — which is fine for the 88% in zone 9a and wrong for the other 12%. Here is the actual split.
| Zone | ZIP codes | Share | |
|---|---|---|---|
| 9a | 78 | 88% | |
| 8b | 11 | 12% |
Zones are published per ZIP code, so yours is exact even though the metro's is not. The hardiness tool will tell you which one you are in.
Your freeze dates
Those are the earliest and latest medians among the 15 stations serving this metro — not an average, and not one station standing in for the rest. Half of years freeze later than a station's own median.
The spread is the point. Even in a metro that is one hardiness zone throughout, its stations disagree about the last spring freeze. Hardiness zone and frost date measure different things — a zone is the average annual coldest night, a freeze date is when the season turns — and a place can be uniform in one and varied in the other. Use the tools below with your own ZIP rather than the ends of this range.
Your growing season
NOAA publishes a growing-season length for each station, and across the 15 stations serving Austin-Round Rock-San Marcos, TX it runs 242–291 days . That figure is published, not computed from the two freeze dates — subtracting one from the other gives the wrong answer wherever a season crosses New Year. Mean summer high (June–August) runs 93–96 °F , at or above the 90 °F point where cool-season crops bolt and tomato and pepper pollen fails — so midsummer sowings of lettuce and its relatives are worth holding here.
When to start seeds in Austin-Round Rock-San Marcos, TX
Every spring job for 63 crop dates, counted from this metro's own last spring freeze. Each is a range across all 15 stations — the earliest and latest that job falls anywhere in the metro — because no one station speaks for the whole area.
| Crop | Job | When | Offset |
|---|---|---|---|
| Green Onions | Start indoors | January 3 – December 26 | 8 weeks before |
| Peppers | Start indoors | January 3 – December 26 | 8 weeks before |
| Broccoli | Start indoors | January 9 – February 3 | 6 weeks before |
| Cabbage | Start indoors | January 9 – February 3 | 6 weeks before |
| Collards | Start indoors | January 9 – February 3 | 6 weeks before |
| Kale | Start indoors | January 9 – February 3 | 6 weeks before |
| Leaf Lettuce | Start indoors | January 9 – February 3 | 6 weeks before |
| Peas | Direct sow | January 9 – February 3 | 6 weeks before |
| Spinach | Direct sow | January 9 – February 3 | 6 weeks before |
| Sweet Potato | Start indoors | January 9 – February 3 | 6 weeks before |
| Tomatoes | Start indoors | January 9 – February 3 | 6 weeks before |
| Bok Choy | Start indoors | January 16 – February 10 | 5 weeks before |
| Kohlrabi | Start indoors | January 16 – February 10 | 5 weeks before |
| Swiss Chard | Start indoors | January 16 – February 10 | 5 weeks before |
| Arugula | Direct sow | January 23 – February 17 | 4 weeks before |
| Baby Salad Greens | Direct sow | January 23 – February 17 | 4 weeks before |
| Beets | Direct sow | January 23 – February 17 | 4 weeks before |
| Green Onions | Direct sow | January 23 – February 17 | 4 weeks before |
| Mustard Greens | Direct sow | January 23 – February 17 | 4 weeks before |
| Okra | Start indoors | January 23 – February 17 | 4 weeks before |
| Radishes | Direct sow | January 23 – February 17 | 4 weeks before |
| Turnips | Direct sow | January 23 – February 17 | 4 weeks before |
| Cabbage | Set out | January 30 – February 24 | 3 weeks before |
| Carrots | Direct sow | January 30 – February 24 | 3 weeks before |
| Collards | Direct sow | January 30 – February 24 | 3 weeks before |
| Collards | Set out | January 30 – February 24 | 3 weeks before |
| Cucumbers | Start indoors | January 30 – February 24 | 3 weeks before |
| Green Onions | Set out | January 30 – February 24 | 3 weeks before |
| Kale | Direct sow | January 30 – February 24 | 3 weeks before |
| Kale | Set out | January 30 – February 24 | 3 weeks before |
| Kohlrabi | Direct sow | January 30 – February 24 | 3 weeks before |
| Kohlrabi | Set out | January 30 – February 24 | 3 weeks before |
| Leaf Lettuce | Direct sow | January 30 – February 24 | 3 weeks before |
| Pumpkins | Start indoors | January 30 – February 24 | 3 weeks before |
| Summer Squash | Start indoors | January 30 – February 24 | 3 weeks before |
| Winter Squash | Start indoors | January 30 – February 24 | 3 weeks before |
| Zucchini | Start indoors | January 30 – February 24 | 3 weeks before |
| Bok Choy | Direct sow | February 6 – March 3 | 2 weeks before |
| Bok Choy | Set out | February 6 – March 3 | 2 weeks before |
| Broccoli | Set out | February 6 – March 3 | 2 weeks before |
| Cilantro | Direct sow | February 6 – March 3 | 2 weeks before |
| Leaf Lettuce | Set out | February 6 – March 3 | 2 weeks before |
| Swiss Chard | Direct sow | February 6 – March 3 | 2 weeks before |
| Swiss Chard | Set out | February 6 – March 3 | 2 weeks before |
| Dill | Direct sow | February 13 – March 10 | 1 week before |
| Bush Beans | Direct sow | February 27 – March 24 | 1 week after |
| Cucumbers | Set out | February 27 – March 24 | 1 week after |
| Pumpkins | Direct sow | February 27 – March 24 | 1 week after |
| Pumpkins | Set out | February 27 – March 24 | 1 week after |
| Summer Squash | Direct sow | February 27 – March 24 | 1 week after |
| Summer Squash | Set out | February 27 – March 24 | 1 week after |
| Sweet Corn | Direct sow | February 27 – March 24 | 1 week after |
| Tomatoes | Set out | February 27 – March 24 | 1 week after |
| Winter Squash | Direct sow | February 27 – March 24 | 1 week after |
| Winter Squash | Set out | February 27 – March 24 | 1 week after |
| Zucchini | Direct sow | February 27 – March 24 | 1 week after |
| Zucchini | Set out | February 27 – March 24 | 1 week after |
| Cucumbers | Direct sow | March 6 – March 31 | 2 weeks after |
| Okra | Direct sow | March 6 – March 31 | 2 weeks after |
| Okra | Set out | March 6 – March 31 | 2 weeks after |
| Peppers | Set out | March 6 – March 31 | 2 weeks after |
| Southern Peas | Direct sow | March 6 – March 31 | 2 weeks after |
| Sweet Potato | Set out | March 6 – March 31 | 2 weeks after |
The week offsets are conventional extension guidance and vary by variety; the freeze dates they are counted from are measured. For a single date rather than a range, run when do I start my seeds? with your own ZIP code.
What survives the winter changes across Austin-Round Rock-San Marcos, TX
Of 74 perennial fruits, nuts, berries, vegetables and herbs, 54 come through the winter in zone 8b and only 46 in zone 9a. That is a different garden at each end of the same metro.
| Zone | ZIPs | Survive | Fail for being too warm |
|---|---|---|---|
| 8b | 11 | 54 of 74 | 11 |
| 9a | 78 | 46 of 74 | 25 |
The last column is the counterintuitive one, and it is why the totals do not simply rise as the winters get milder. Most temperate fruit needs a documented number of hours below about 45 °F to break dormancy and set a crop, so an apple fails in a winter that is too warm; currants and rhubarb cook in the summer heat that comes with it. See the full list with reasons.
The 15 stations behind these numbers
Every figure above comes from these, and each is named so you can check it. Distances vary by ZIP code, so the tools report yours rather than this page guessing.
| Station | NOAA ID | Last spring freeze | First fall freeze | Season |
|---|---|---|---|---|
| Austin 33 NW, TX | USW00023907 | March 2 | November 29 | 274 days |
| Austin 6S, TX | USC00410431 | March 10 | November 17 | 252 days |
| Austin Bergstrom AP, TX | USW00013904 | March 12 | November 16 | 252 days |
| Austin Great Hills, TX | USC00410433 | March 11 | November 20 | 254 days |
| Austin-Camp Mabry, TX | USW00013958 | February 20 | December 3 | 291 days |
| Canyon Dam, TX | USC00411429 | March 1 | December 1 | 276 days |
| Cedar Creek 5 S, TX | USC00411541 | March 14 | November 19 | 250 days |
| Dripping Springs 6 E, TX | USC00412585 | March 17 | November 13 | 242 days |
| Elgin 1 N, TX | USC00412820 | March 4 | November 24 | 264 days |
| Georgetown Lake, TX | USC00413507 | March 6 | November 24 | 259 days |
| Granger Dam, TX | USC00413686 | March 5 | November 22 | 261 days |
| Luling, TX | USC00415429 | March 5 | November 23 | 263 days |
| San Marcos, TX | USC00417983 | February 28 | November 29 | 273 days |
| Smithville, TX | USC00418415 | March 12 | November 19 | 251 days |
| Taylor 1Nw, TX | USC00418862 | March 8 | November 21 | 257 days |
These are medians, not averages — NOAA publishes freeze dates as a probability distribution, and half of years freeze later than the date shown.
Work out your own dates
Each of these takes a ZIP code and answers for that ZIP alone, citing the station it used and how far away it is. There is a ZIP box in the header of every page.
- What survives my winter?
Runs on the hardiness zone, so it answers for all of Austin-Round Rock-San Marcos, TX at once — zone across 74 perennial fruits, berries, vegetables and herbs.
- When do I start my seeds?
Dates every spring job from your own last freeze — sow indoors, set out, direct sow.
- When do I sow the next round?
How often each crop is worth re-sowing, and when the next sowing is due.
- What can I still plant?
Counts the growing days left before your first fall freeze, crop by crop.
Where these numbers come from
The hardiness zone is the USDA 2023 Plant Hardiness Zone Map, published per ZIP code by PRISM at Oregon State. The freeze dates are NOAA's 1991–2020 Climate Normals, read from every station whose normals cover a ZIP code in this metro. Nothing here is estimated, and no station stands in for another.
This page names no single station on purpose. Picking one to represent a metro sounds reasonable and is not: the station serving the most ZIP codes is an artifact of where ZIP centroids happen to fall, and it selects a lock on the Monongahela for Pittsburgh and a far southern suburb for Chicago. A range across every station is true; a single cited date for a whole metro is not.