How Do Sweet Potatoes Grow?

How Do Sweet Potatoes Grow

Last Updated on August 15, 2023 By Emma W. Thomas

Sweet potatoes grow from slips, which are sprouts obtained from mature sweet potatoes. Plant slips in well-drained soil, spacing them 12-18 inches apart. They require warm temperatures (75-95°F) and take around 90-170 days to mature. Harvest when leaves turn yellow, usually in fall.

How to Plant, Grow and Harvest Sweet Potatoes

Sweet potatoes are not only a delicious staple in many cuisines, but they are also packed with nutrients. If you’ve ever wanted to try your hand at growing your own supply of this versatile root vegetable, look no further! In this article, we will guide you through the step-by-step process of planting, growing, and harvesting sweet potatoes. Let’s get started!

  1. Choosing and Preparing the Site:
  • Select a sunny location in your garden that receives at least 6-8 hours of direct sunlight daily.
  • Ensure the soil is well-draining and loose, with a pH level between 5.0 and 6.5.
  • Remove any rocks, weeds, or grass from the designated area to reduce competition for nutrients.
  1. Preparing Sweet Potato Slips:
  • Purchase disease-free sweet potato slips from a reputable nursery or produce store.
  • Trim each slip to about 6-10 inches in length, ensuring it has at least four healthy leaves.
  • Place the slips in a container with water, ensuring that the lower ends are submerged. Leave them indoors for about two weeks until roots develop.
  1. Planting:
  • Dig furrows around 8-12 inches deep and 3-4 feet apart.
  • Add compost or well-rotted organic matter to enrich the soil before planting.
  • Place the sweet potato slips into the furrows, spacing them around 12-18 inches apart.
  • Cover the slips with soil, leaving around 2 inches of the stem above the ground.
  1. Care and Maintenance:
  • Water your sweet potatoes consistently, providing about an inch of water per week. Increase the frequency during dry spells.
  • Mulch around the plants to retain soil moisture and suppress weed growth.
  • Avoid using nitrogen-rich fertilizers as they can promote excessive vine growth, resulting in smaller tubers.
  • Regularly inspect your plants for pests like sweet potato weevils or beetles. Remove any affected plants promptly.
  1. Harvesting:
  • Sweet potatoes are usually ready to harvest around three to four months after planting.
  • Before digging, cut back the foliage a week prior to harvest to allow the skin to harden and improve flavor.
  • Gently dig around the plants using a garden fork, being careful not to puncture or bruise the tubers.
  • Lift the sweet potatoes out of the soil, brush off excess dirt, and store them in a cool, dry place for about two weeks to cure. This process improves their flavor and allows the skin to toughen.

Benefits of Sweet Potatoes

Sweet potatoes are beautiful, whether you place them in a garden, a trellis, or even a simple container. The starchy, sweet-tasting tuberous roots have several health benefits that make them a good part of your diet. They are loaded with various minerals, fiber, vitamins, and phytonutrients that boost your body and mind. They can also function as trailing houseplants or as temporary groundcover.

You can boil, bake, or use them raw in desserts, soups, casseroles, stir-fries, or bread. You can also try them in sweet potato fries at home.

How to Plant Sweet Potatoes in Your Backyard

Sweet potatoes do well in a sunlit vegetable garden, but they can as well flourish in other outdoor space areas. The warm-weather crops can grow under different conditions, from temperate climates to tropical regions. 

These crops can thrive in poor soil, but they may develop malformed roots in clay or become long and stringy in sandy soil. Follow these steps;

Step 1

Create broad, long 10-inch high ridges that are 3 1/2 –feet apart to achieve a suitable environment. ( Each 10-foot row should produce eight to ten pounds of potatoes.)

Step 2

Use a lot of manure and avoid nitrogen-rich fertilizers that can produce stunted tubes and lush vines. Cover the lifted rows using black plastic to retain the soil’s heat and enhance strong growth.

Step 3

Get slips (plant root sprouts) from mail-order suppliers or nurseries. Sweet potatoes bought from stores are usually waxed to avoid sprouting, so spare a few tubers from your crops to plant in the next season.

Step 4

If you are planting sweet potatoes outdoors in your place, put the roots in a container of moist sand, chopped leaves, and sawdust in a warm area. It would be best if you did this about six weeks before planting time.

After your shoots sprout and reach a length of 6 to 9 inches, cut them from the root. Cut the bottom inch and discard it as this portion may harbor disease-causing organisms. Plant the crops in bright sun about 3 to 4 weeks after the last frost.

Make holes six inches and twelve-inches apart and cover the slips up to the top leaves, compress the soil gently down but tightly, and water them well.

Step 5

Mulch the vines a fortnight after planting if you are not using black plastic. Mulching helps to conserve moisture, smother weeds, and keep the soil loose for roots to develop. Lift the longer vines occasionally to prevent them from forming roots at the joint and also undersized tubers.

Avoid touching the plants as this may cause wounds that make them vulnerable to disease spores.

Step 6

If the weather is dry, give your plants an inch of water once per week until it is two weeks to harvesting. Allow the soils to dry a bit and avoid overwatering, which can cause the plants to rot.

Requirements for sweet potatoes to grow

Sweet potatoes require specific conditions for them to thrive well which include;

  1. Soil

Ensure that you plant your sweet potatoes in well-drained soil with high organic matter content. You can choose sandier ground instead of using dense clay.

2. Light

Sweet potatoes should be planted in full sun to partial shade. These crops do well in full sun and appreciate a little afternoon shade in dry, hot regions.

3. Water

Sweet potatoes endure growing in dry soil once they are established. Ensure that you keep the soil consistently moist with one inch of water once every week. You don’t have to water the crops during the last three to four weeks before harvesting to prevent the mature tubers from splitting.

4. Fertilizer

Sweet potatoes do not require fertilizer at the time of planting. But you can fertilize the crops about two weeks after transplant with potassium and phosphate fertilizers. You can also add compost to the beds before transplanting.

5. Humidity and temperature

You should not plant sweet potatoes outdoors until the soil is warm enough. They need a temperature range between 60-85 degrees Fahrenheit and air temperature range between 65-95 degrees.

How to grow sweet potatoes in pots

There are two main types of sweet potatoes i.e., edible roots bred for vegetables and inedible ones produced for their ornamental trailing foliage. The two types are easy to grow in pots and are technically edible, though the ornamental ones are described as ‘barely edible’ as their roots are smaller and less sweet.

Both ornamental and edible sweet potatoes grow well in large pots and sunny conditions. They are available for sale as small container crops in the spring. You can also grow them by sprouting slips from tubers.

Tools and supplies needed

To propagate your sweet potatoes in a pot, you will need;

  1. Sweet potato tubers
  2. Toothpicks
  3. Knife
  4. A shallow dish
  5. Glass container
  6. Planting containers
  7. Good-quality potting soil

Look for sweet potato tubers that are firm, with no bad spots, and which have not been refrigerated. Follow the steps below;

  1. Prepare the tubers

If you have large tubers, you will need to cut them into large pieces to place them in water for sprouting.

  • Use a sharp knit to cut the tubers into small pieces, the size of the opening on the jar.
  • Locate the center of each tuber piece and insert about three or more toothpicks into it. Let the toothpicks go into the tuber about 1/2-1 inch and space them evenly along the circumference. If the tuber is hardened, use a thin hole to drive the toothpicks.

2. Place the tubers in water.

Position the tubers in water to sprout into slips, which will be used to produce new sweet potato plants. 

  • Place the tuber on top of the glass and let the ends of the toothpicks rest on the edge with the tuber’s end facing down.
  • Fill a glass or jar with enough water to cover the bottom part of the tuber.
  • Place the container on a windowsill where there is sunlight. Make sure you change the water occasionally and allow the bottom of the tuber to remain submerged in water.
  • Wait until green growth sprouts from the bottom of the tuber.

Avoid tap water as it may contain chlorine and other minerals that prevent the tuber from sprouting. You can use distilled water in place of tap water.

3.  Separate the slips    

After the tubers have sprouted, separate them into slips that can be planted individually.

  • Take each sprout and separate it carefully from the tuber. Twist the slip gently as there may be a rudimentary root joined to it.
  • Place every slip into a shallow bowl and let the stem submerge in water and the leaves hang over the edge of the container. Within a few days, new roots will start to grow from the bottom of the slip.       
  • You can plant the slips in potting soil when the roots are about an inch long. Discard any wilting slip or any that has no roots as they are not viable.          

4. Plant the slips in containers

If you are planting your sweet potato vines for decoration, look for a small seedling pot with good drainage. Once the plants thrive indoors, you can transfer them to large containers with other plants. If you want to grow edible tubers for vegetables, you can use a bucket or a large container to give them adequate room to grow.

You can also use the seedlings from the pot to plant the edible sweet potatoes on the ground.

  • Fill up the container with excellent-quality potting soil up to one inch below the rim. Ensure you use loose soil for the tubers to grow large.
  • Fill the bottom of the container with slow-release fertilizer and mix it with the soil.
  • Using a stick, make a hole at the center of the soil and let it be deep enough to cover the roots of the slip. Put one or two slips into the hole gently and pat the soil firmly around them and ensure there are air pockets close to the roots.
  • Water thoroughly and add more soil if it settles.
  • Put your pot indoors in a sunny spot and keep the soil moist and not wet.

Your plants may grow fast, depending on the size of the container. You may need to prune the roots or change the pots if they become root-bound within the container.

5. Moving your sweet potatoes outdoor

Before moving your sweet potatoes outdoors, ensure that the soil is at least 60 degrees Fahrenheit. You can wait for around one month after the last frost date and take time to prepare your planting site to get loose soil.

6. Harvesting

For vegetable varieties, you can harvest them at any stage, and they will be edible. Depending on which type you have, sweet potatoes usually take 100-140 days to mature fully. For best edibility, make sure you harvest before the first frost in the fall.

Cure the sweet potatoes in warm water and dry them for ten days to two weeks before eating. Treating them this way will give the best flavor and extend the shelf life.