Plant sweet potato slips in Texas after the last freeze has passed and the soil has warmed, which usually means weeks after the frost date. Around Houston, on the mild Gulf end of the state, that puts planting in spring with a long summer left for the roots to size up. Farther north and west the calendar slides later and the window narrows.
When the soil is warm enough in Texas
The question most gardeners bring is the earliest safe day to set slips outside. For Houston, NOAA’s 1991-2020 climate normals at Houston Intercontinental (station IAH) put the last spring 32°F freeze between February 4 and March 1, using the 30 to 70 percent probability band. A normal is an average of many springs, so a late freeze can still land after the later date in any given year.
Sweet potatoes are tropical vines, and they respond to soil temperature. Soil lags behind the air, so it warms after the freeze risk ends. Slips set into cool ground grow slowly and are more likely to rot. Waiting a few extra weeks costs very little, because a slip planted into warm soil catches up fast.
How do you know the soil is warm enough for sweet potato slips?
Use a soil thermometer and read it when the ground is at its coolest. Look for several days in a row of mild nights as well. Okra makes a handy yardstick: if the bed is warm enough for okra seed to come up quickly, it is ready for slips. Your county office at Texas A&M AgriLife Extension can give you the soil temperature to aim for in your area. Black plastic laid over the bed ahead of time helps in cooler parts of the state.
Does the Houston date apply to the rest of Texas?
No. Texas runs from zone 6a to 10a on the USDA Plant Hardiness Zone Map, a system built on the average annual extreme minimum temperature. The Houston dates describe the mild Gulf end. The Panhandle freezes later in spring and earlier in fall. The Hill Country and North Texas follow their own calendars. Even inside Houston, Hobby airport runs about two weeks milder than IAH. Treat the Houston dates as one reference point, then adjust for your own county and your own yard.
How long the season lasts here
The reference station at IAH has roughly nine to ten and a half months between the mean last spring frost (February 4 to March 1) and the mean first fall frost (December 1 to December 19). That is a long runway for a crop that needs a warm stretch to finish. Sweet potato vines are tender, and a frost blackens them.
Can you plant sweet potatoes twice in one season in Texas?
On the Gulf end, yes, within limits. A second planting of slips in early summer can follow an early crop of something else, or you can stagger two plantings a few weeks apart so the harvest does not all arrive at once. The later planting still needs enough warm weeks to bulk up before the first fall frost, so do not push it too late. Farther north and west, where the window is shorter, the first planting is usually the only one. There, set slips as soon as the soil is truly warm and look to the earliest types. For the mechanics of slips and heat, see Growing Sweet Potatoes: Slips, Heat, and a Careful Cure. A shorter-season state such as Maryland is covered in Growing Sweet Potatoes in Maryland.
How do you harvest and cure sweet potatoes safely?
Dig before a hard freeze, or promptly if frost blackens the vines. Handle the roots gently, because skin scrapes invite rot. Curing means holding the roots in a warm, humid place for a period so the skin toughens and small wounds heal. After that, store them in a dry, moderately cool spot such as an interior closet. Never put sweet potatoes in a refrigerator or a cold cellar. Cold injury is permanent and is one of the most common ways a good harvest is ruined.
Inspect every root before it goes into storage and again from time to time:
- Firm skin with no sunken or dark patches.
- No weeping or wet spots.
- No sour or off smell.
A soft patch or a weeping spot settles the question: discard that root. A root that looks sound is not guaranteed safe, so I never treat appearance as a promise about keeping.
Heat and water in Texas
At the Houston reference station, 102.4 days a year reach 90°F or more (NOAA 1991-2020 normals). That count is for one station, not the whole state. It does describe the Gulf end well: a place where sweet potatoes are a routine summer crop rather than a project. Where summers run cooler, as in much of the northern part of the country, gardeners resort to plastic, ridges and early types to get the same result.
Do warm days or warm nights matter more?
Sweet potatoes want accumulated warmth, and warm nights count as much as hot afternoons. Houston’s humid summer nights keep growing through the dark hours, and the roots keep swelling. Hot, dry air can still stress vines in the western parts of Texas, where mulch and steady irrigation matter more.
How much water do sweet potatoes need in a Texas summer?
Houston’s reference station averages about 14.6 inches of rain across June, July and August, out of 51.8 inches for the year. By month, June brings 6.0 inches, July 3.77 and August 4.84. July is the driest, and it lands right when the roots are bulking up. Those are normals for one station over 1991-2020, so a rain gauge on your own plot tells you what actually falls.
Soil changes what that rain means. Sand lets an inch drain away within the day, so a wet summer on sandy ground can still need watering every second day. Clay holds an inch of rain for a week. Heat speeds evaporation, and a single summer thunderstorm often runs off instead of soaking in. Water deeply but not constantly during dry stretches, and avoid soaking the bed after a long dry spell. Big swings between dry and wet are what split roots near the end of the season.
Humidity brings disease pressure. Ridges or raised rows let heavy rain drain away from the roots, and spacing plants for airflow keeps the foliage drier. Gardeners in Louisiana deal with the same Gulf humidity, and Growing Sweet Potatoes in Louisiana covers that side of the work.
Which sweet potatoes suit Texas
Choose by type, and let climate pick the type. In a humid summer, disease resistance comes first. Look for types bred for resistance to soil rot and nematodes, and buy certified disease-free slips from a reputable source. Where summers are hot, favor vigorous vining types that shade their own roots, and give them airflow through ridges and sensible spacing. Where the season is short, as in the Panhandle, the earliest-maturing types are the better bet. Flesh color, whether orange, white or purple, is a matter of taste and texture and has little to do with climate.
I have left out named varieties on purpose. Texas stretches across zones 6a to 10a, and a type that thrives on the Gulf coast may do poorly on the High Plains. The only recommendation worth following is the one from varieties trialled near you. Texas A&M AgriLife Extension and your county office can tell you which ones have been tested locally. When you call, ask three things:
- Which types have been trialled in your county.
- How they handle local soil diseases and nematodes.
- When local growers set slips and when they dig.
One more correction for the bed plan. Sweet potato belongs to the morning glory family, which makes it unrelated to potatoes, tomatoes and other nightshades. The supermarket label “yam” is wrong as well, since true yams are a different plant. Rotation with potatoes is therefore irrelevant. Rotating away from sweet potatoes in the same bed from year to year still helps limit soilborne disease.
Common questions
Can I plant sweet potatoes in Texas in summer?
On the Gulf end, a planting in early summer can work if enough warm weeks remain before the first fall frost, which falls between December 1 and December 19 at the IAH station. Farther north the first fall freeze arrives sooner, so a late planting runs out of time. Ask your county extension office how late local growers still plant.
Do I rotate sweet potatoes with potatoes?
Potatoes belong to the nightshade family, while sweet potatoes belong to the morning glory family. They do not share the same relatives, so the two do not compete in a rotation. Even so, avoid planting sweet potatoes in the same spot year after year.
Why do my sweet potatoes crack?
Splitting usually follows a swing from dry soil to heavy rain or heavy watering. Even moisture through the hottest stretch helps, particularly on sandy ground that dries quickly. Ridges also let excess rain drain away.
Can I keep sweet potatoes in the refrigerator?
No. Refrigerators and cold cellars cause cold injury, and the damage cannot be reversed. After curing, keep them in a dry, moderately cool spot and check them regularly. A soft patch or weeping spot means that root goes in the trash.