In Houston, the safest outdoor sowing of winter squash begins after March 1 and needs to finish before the first fall freeze arrives, as early as December 1. Those dates come from NOAA’s Houston figures, which sit at the mild Gulf end of Texas. The rest of the state shifts them, sometimes by months, and this page shows how.
The short answer for Texas
Sow winter squash outdoors after the last spring freeze has passed, and plan to harvest before the first fall freeze. For Houston’s airport station (IAH), NOAA’s 1991-2020 normals put the last spring freeze between February 4 and March 1, and the first fall freeze between December 1 and December 19.
Both ranges are probabilities of a 32°F freeze. Each covers the middle of the odds, the stretch where the chance sits between 30 and 70 percent. They are not forecasts, and they do not promise a freeze on any given date. The figures come from NOAA NCEI station USW00012960.
Reading the spring band
Sowing on February 4 is a bet, because a freeze at that point is still a live possibility. Winter squash seedlings have no frost tolerance, so one cold night can end the planting. Waiting until after March 1 is the conservative choice. Soil temperature is a separate question from the freeze date, since squash seed sulks in cold, wet ground even when no freeze is coming (the last section covers how to check by hand).
Reading the fall band
Count forward from March 1 to December 1 and you get roughly nine months. That sounds generous, and for Houston it is. Winter squash needs several months to take a seed to mature, cured fruit, so the real planning runs backward from the fall band. Fruit that ripens before December 1 never meets the freeze risk at all.
One caution about these numbers: they describe Houston, not Texas. Even inside Houston, Hobby airport runs about two weeks milder than IAH. For the broader picture of growing squash across the state, see Growing Winter Squash in Texas.
What will not work here
A short season is not Houston’s problem. Heat and humidity are, and they defeat different habits.
Planting into the worst of the heat
The reference station averages 102.4 days a year at or above 90°F. That is the measure of summer heat load, and it drives water demand and heat stress. A spring sowing that falls behind schedule grows into that heat before it has set fruit. Vines that should be ripening in cool weather end up flowering through the hottest stretch of the year, when stressed plants tend to drop blossoms and stall.
The fix is to sow at the front of the window, after the March 1 end of the spring band and not weeks later. Squash planted in the second half of the window carries the cost of its lateness through every hot week that follows.
Close spacing in a wet summer
Houston is not a dry-summer place. About 14.6 inches of rain fall across June, July and August, out of 51.8 inches for the whole year. June is the wettest of the three at 6.0 inches, August follows at 4.84, and July is the driest at 3.77. Add warm nights and heavy humidity, and crowded vines stay damp for hours after every storm. Damp foliage invites mildew and rot, and a dense canopy gives them somewhere to start. Give each plant room to dry, and train vines so air can move through them.
Watering by the calendar
A fixed weekly watering day fails in both directions. Rain here often arrives as a single thunderstorm, and much of that runs off rather than soaking in, especially when the ground is baked from the heat. Soil then decides the rest. A sandy bed lets an inch of rain through within the day and may need water every second day, even in a wet month. A clay bed can hold the same inch for a week and drown roots if you water on schedule anyway.
These are normals for one station over 1991-2020, so they describe what the region can usually expect, not what your yard received last week. A rain gauge on your own plot settles it better than any average. And a Houston calendar will not work in Amarillo or Lubbock, which brings us to how much Texas varies.
What changes across Texas
On the USDA Plant Hardiness Zone Map 2023 (built on 1991-2020 normals), Texas runs from zone 6a to 10a. That is not one garden, and there is no single answer for the state. The zone is built on one variable only, the average annual extreme minimum temperature, so it tells you how cold the worst night gets, not the date of the last spring freeze. It is still a reliable sign of how far a place sits from Houston’s mild end.
The Houston dates here are the Gulf end of that spread. The Panhandle freezes months earlier in fall and months later in spring, so its frost-free stretch is far shorter than the roughly nine months Houston enjoys. Hill Country and North Texas differ again, each with its own pattern of late freezes and early ones.
A reader in the north or at altitude should shift three things. Start later, because the spring freeze band lies later. Finish earlier, because the fall band arrives sooner. And lean toward faster-maturing types, since the slowest winter squash can run out of season where Houston’s would not. The best winter squash to grow in Texas sorts varieties by exactly that trade-off.
To find your own zone, use the USDA Plant Hardiness Zone Map and look up your location. Do not guess from a neighbor’s tag at the nursery. A zone is a starting point, and your county’s frost dates are the better guide.
Where to check this for your own county
Your state extension service is the next stop. Texas A&M AgriLife Extension is the land-grant university’s outreach arm for Texas, and its county offices work from local conditions rather than a single station.
Look for two things there:
- The local planting calendar for warm-season vegetables, which should name sowing windows for your area.
- The winter squash varieties trialled in your county, meaning ones actually grown and evaluated near you.
A county recommendation beats a state one, every time. This page is the state one, and its dates come from a single Houston station. Extension staff know which parts of your county run colder, which soils are heavy, and which pests arrive first. If their calendar and this page disagree, follow theirs.
Checking this against your own garden
Your own observations outrank every date above. Three are worth watching, and none needs an instrument.
First, soil warmth by feel. Push your hand into the bed in the morning, about as deep as your fingers reach. If the soil feels cool and damp, seed will sit and may rot. If it feels comfortably warm, the seed is likely to come up fast. A bed that warms early tells you that spot is a mild pocket, perhaps near a south-facing wall or on a raised bed.
Second, the first flush of male flowers. On squash they open before the female ones. When they show, the plant has settled in. If they appear and then vanish in a heat wave, you are learning how hot your microclimate runs.
Third, the first true leaves. The seed leaves come up first, and the true leaves follow. Seedlings that stall at that stage point to cold soil or poor drainage. Ones that scorch or wilt by afternoon point to a spot that bakes. Note the date you see them, and next year you will have your own calendar.
Common questions
Can I sow winter squash in Houston in early February?
It is a gamble. The last spring freeze at IAH falls between February 4 and March 1 in the 30-70% probability band, so a freeze after early February is still plausible. Sowing after March 1 is the safer choice.
Do these dates work for Dallas, Lubbock or Amarillo?
No. They come from one Houston station at the mild Gulf end of Texas. The Panhandle freezes months earlier and later, and North Texas and Hill Country differ again. Use your county extension office for local dates.
Can I sow a second crop in summer for fall harvest?
The fall freeze band (December 1 to December 19 at IAH) leaves room to try it in Houston. But seedlings would establish during the hottest weeks, with 102.4 days a year at or above 90°F at the reference station. Check which varieties and sowing dates your county extension recommends before committing.
Does a wet summer mean I can skip watering?
Not necessarily. Houston gets about 14.6 inches across June, July and August, with July the driest at 3.77 inches. But storm rain runs off hot ground, and sand and clay hold it very differently. A rain gauge in your own plot shows what actually reached your squash.