Growing Sweet Potatoes

Planting, Growing, and Harvesting Sweet Potatoes

Sweet Potatoes
Bonnie Taylor Barry/Shutterstock

Are you growing sweet potatoes? With their deep orange flesh, these edible roots have a naturally-sweet flavor and are a top source of beta-carotene. Thriving in warm soil, unlike regular potatoes, sweet potatoes will be ready to harvest just as the ends of the vines begin to turn yellow, or just before frost. Perfect timing for autumn foods and the holiday table!

The sweet potato is a large, sweet-tasting root of the morning glory family. (Regular potatoes belong to the nightshade family). This is a very undemanding crop to grow; sweet potatoes are drought- and heat-tolerant and have few pests or diseases. The sweet potato is also very nutritious and relatively low in calories. In addition, we think that the sweet potatoes’ lush vines make a lovely ground cover for beds.

The only major requirement for sweet potatoes is sun and warm soil; this is a tropical plant.

Though traditionally more of a Southern crop, there are many short-season varieties of sweet potato today which will grow in the North (even Canada!) as long as they have several months of warm weather. Mulching planting beds with black plastic warms soil in northern regions. 

Sweet potatoes aren’t started by seed like most other vegetables, they’re started from slips—small rooted pieces of tuber which are sliced right off the sweet potato. 

Sweet Potatoes vs. Yams

Sweet potatoes are sometimes confused with yams. 

  • “True yams” are rarely found in U.S. grocery stores and are starchy, dry tubers from Africa. They are related to lilies and have a cylindrical shape with blackish or brown, bark-like skin and white, purple, or reddish flesh. You can often find them in specialty stores.
  • In U.S. grocery stores, you’ll often find two different type of sweet potatoes: “firm” and “soft.” Groceries stores will often call the “firm” type a “sweet potato” and the “soft” type a “yam” to differentiate the two, even though neither is a true yam. To add to the confusion, it’s the “soft” sweet potato with the deep orange flesh and copper skin that we usually plant and eat. Even if stores call it a yam! Just look carefully at the flesh and skin to confirm which is which.

Sweet potatoes. Photo Credit: Brent Hofacker/Shutterstock
Photo Credit: Brent Hofacker/Shutterstock


When to Plant Sweet Potatoes

  • Sweet potatoes need 3 to 4 months of warm temperatures in order to produce a worthwhile harvest, so the key is to plant them early enough for them to mature properly, but not early enough for them to get killed by a late spring frost.
  • Slips should be planted in warm soil 3 to 4 weeks after the last spring frost, once nighttime temperatures have reached at least 55°F (13°C). (See local frost dates.)

Choosing and Preparing a Planting Site

  • Ensure you have a location in a sunny spot with loamy, well-drained soil. Sweet potatoes aren’t too picky, but they do prefer soil on the sandier side, and need plenty of air space in the soil for roots to reach down. If your soil is clay, rocky, or compacted, consider raised beds.
  • Pick a location with plenty of room for those vines to run (3 feet between rows so the vines).
  • If you live in the nothern US or Canada, consider covering the growing area with fabric mulch about 3 weeks before planting. This helps to warm the soil.
  • Till the area of the garden you will be using to a depth of 8 to 10 inches. Create raised mounds 6 to 8 inches tall and about 12 inches wide. Use fertile, well-drained soil.
  • If a soil test indicates poor soil, amend appropriately. Consider natural fertilizers such as compost or manure, as sweet potatoes are extremely sensitive to aluminum toxicity. 

How to Plant Sweet Potatoes

  • Sweet potatoes are typically grown from slips, which are sprouts that are grown from stored sweet potatoes. You can buy slips from garden centers, nurseries, or local farmers.
  • You can also create your own slips to plant in the spring. In November (this is when the best of the new harvest will be out), go to your supermarket and look for unblemished and uncracked medium-size sweet potatoes. One sweet potato should yield about 12 plants.
    • Store sweet potato slips in a well-lit room with a temperature between 65° and 70°F. Keep them there until about 90 days before the last spring frost date. They will then need to be embedded in soil for 90 days and kept continuously warm and moist.
      • Use a 1 to ½ gallon pot for every two slips. Remember to poke drainage holes in the bottom of the pot and fill it with 3 inches of mulch, followed by garden or potting soil. Plant the slips in the pot at a 45° angle so that the sprouts will grow above the soil. When the slips are 6 to 12 inches tall, you can plant them outdoors, as long as all danger of frost has passed.
  • Plant the slips 12 to 18 inches apart in the bed. Plant the slips deep enough to cover the roots and about ½ inch of the stem.
  • Water the slips with a starter solution (a liquid fertilizer) that is high in phosphorous, then water generously for a few days to make sure that the plants root well.
  • See more tips for growing sweet potatoes.


How to Grow Sweet Potatoes

  • Side-dress the sweet potato plants 3 to 4 weeks after transplanting with 3 pounds of 5-10-10 fertilizer per 100 feet of row. If you have sandy soil, use 5 pounds.
  • Weed the sweet potato beds starting 2 weeks after planting to keep weeds down. Remember to reshape the beds with soil or mulch.
  • Avoid deep digging with a hoe or other tool that disturbs the feeder roots.
  • Remember to keep the plants watered weekly, especially during mid-summer. Deep watering in hot, dry periods will help to increase yields, although if you are planning to store some of the potatoes, do not give the plants extra water late in the season, as it could cause cracking of the tuber’s skin.
  • For good harvests, do not prune the vines, because they should be vigorous.


  • Flea beetles
  • Sweet potato scurf
  • White blister
  • Fungal leaf diseases (Alternaria leaf spot and blight, Botrytis)
  • Stem rot


How to Harvest Sweet Potatoes

  • You can start digging up the potatoes as soon as they are big enough for a meal. Often, this is 3 to 4 months from when you planted the slips (most varieties take at least 100 days to reach maturity).
  • Usually, sweet potatoes are ready to harvest when the leaves and ends of the vines have started turning yellow, but you can leave them in the ground up until the fall frost.
  • Since the roots spread 4 to 6 inches deep in the soil, a spade fork is useful when digging up the potatoes. Loosen the soil around the plant (18-inch diameter) so you do not injure the tubers. It’s fine to cut some of the vines away.
  • Pull up the primary crown of the plant and use your hands to dig up the tubers. Handle the sweet potatoes carefully, as they bruise easily. 
  • After digging up the tubers, shake off any excess dirt, but do not wash the roots.


  • You must cure sweet potatoes or they will not have that delicious, sweet taste. Curing the potatoes allows a second skin to form over scratches and bruises that occur when digging up the potatoes. To cure, keep the roots in a warm place (about 80°F/27°C) at high humidity (about 90%) for 10 to 14 days. A table outside in a shady spot works well. For best curing, make sure that the potatoes are not touching one another.
  • After curing, throw out any bruised potatoes, and then wrap each one in newspaper and pack them carefully in a wooden box or basket. Store the sweet potatoes in a root cellar, basement, or other place with a temperature of at least 55°F/13°C.  
  • If stored at a temperature range of 55–60°F (13–15.5°C) with high humidity, the tubers should last for about 6 months. When removing the potatoes from storage, remember to be gentle; do not dig around or else you will bruise the potatoes.

Recommended Varieties

Wit & Wisdom


Cooking Notes

Check out our ten best sweet potato recipes!

To the cook, sweet potatoes are easier than pie (or sweet potato pie!).

  • They can simply be scrubbed, poked with a fork in a few places, and baked at 400°F for 35 minutes to one hour, until they give a bit when you squeeze them in your pot-holder-protected hand.
  • In the microwave, a whole sweet potato baked on high should be ready in 4 to 6 minutes. It may still feel firm when done; let it stand about 5 minutes to soften.
  • Sweet potatoes can also be steamed whole (cleaned and unpeeled) for about 40 minutes or until tender, or cooked whole (cleaned and unpeeled) in boiling salted water for about 35 minutes. (Boiling reduces the flavor considerably.)
  • Immerse cut raw sweet potatoes in water until you’re ready to cook them; they will darken otherwise.

As a general rule, don’t substitute sweet potatoes for regular potatoes in recipes; the two aren’t related. Sweet potatoes don’t hold together the way potatoes do, and their strong flavor can overwhelm a dish meant for a milder potato taste. Sweet potatoes are also not related to yams. But they make a fine substitute for pumpkin, especially in desserts.


Growing Sweet Potatoes

Botanical Name Ipomoea batatas
Plant Type Vegetable
Sun Exposure Full Sun
Soil Type Loamy, Sandy
Soil pH Neutral
Bloom Time Summer
Flower Color Purple
Hardiness Zones 3, 4, 5, 6, 7, 8, 9, 10, 11
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