Sweet Potatoes for the Home Garden: Grow Your Own Slips and Feed Your Family All Winter

You pick up a sweet potato at the store and think it would be nice to grow some. The problem is that unlike tomatoes or peppers, you cannot plant a piece of sweet potato in the ground and expect something to grow. Sweet potatoes grow from slips, which are sprouted shoots that come from a whole tuber.

Most beginners either order slips online or give up. Neither option has to be the case. A grocery store sweet potato, a jar of water, and a few weeks of patience will give you enough slips to plant a garden bed that produces enough food to last through winter.

Understanding What You Are Growing

A sweet potato is not the same thing as a regular potato. They are different species with different growing habits. Regular potatoes form tubers underground and grow from cut pieces of the tuber. Sweet potatoes form their storage roots along runners that spread across the soil surface.

You start a sweet potato garden from a slip, which is a shoot that sprouts from a whole sweet potato. The slip has roots at its base and a stem with leaves at the top. That slip becomes the plant. The plant sends runners along the ground and develops new tubers along those runners.

One good slip produces several tubers. A modest garden of ten to twelve plants can easily feed a family of four through the colder months.

Sprouting Your Own Slips

You can start slips about eight to twelve weeks before you plan to plant them outdoors. For Zone 7a, that means starting in late March or early April so the slips are ready by late May.

Here is the method that works:

• Choose a healthy, firm sweet potato from the grocery store. It does not have to be organic. Conventional tubers work fine for slip production.
• Push three or four toothpicks into the sides of the potato, spaced evenly around it. These will hold the potato in place above the water line.
• Set the potato in a jar or glass so the toothpicks rest on the rim. The bottom third of the potato should be submerged in water.
• Place the jar in a warm, bright spot. A windowsill works. A shelf near a heater works too. The temperature should stay above 70 degrees Fahrenheit.
• Add water as needed to keep the bottom third of the potato covered. Do not let the entire potato sit in water. It will rot.

Within two to three weeks, you should see sprouts breaking through the skin. Some sections of the potato will sprout more vigorously than others. That is normal.

When the slips reach about four to five inches tall and develop small roots at the base, they are ready to separate from the parent tuber. Gently twist or cut them off as close to the potato as possible. If a slip already has roots, that is a bonus. Transplant it directly. If it has no roots yet, set the base in a shallow dish of water and roots will form within a few days.

One sweet potato can produce ten to fifteen slips over a period of six to eight weeks. You can keep sprouting from the same potato as long as it stays firm. If it begins to shrivel or rot, start a fresh one.

Planting the Slips

Plant sweet potato slips after the soil has warmed to 65 degrees Fahrenheit and all danger of frost has passed. In Zone 7a, that is usually mid to late May. Planting too early in cold soil is the single most common reason sweet potato gardens fail. The slips will sit in the ground and rot before they can establish.

Choose a location that gets full sun. At least eight hours of direct light per day is ideal. Sweet potatoes are heat lovers and they grow slowly until the soil is genuinely warm.

Sweet potatoes grow best on raised ridges or mounds. This gives the roots room to expand, improves drainage, and allows the soil to warm faster than flat ground. Build ridges about eight inches high and twelve inches wide. Space the ridges about three to four feet apart.

Plant each slip by burying it two to three inches deep, angled into the mound. Remove the bottom leaves so they do not touch the soil and rot. Space slips about twelve to eighteen inches apart along the ridge.

Water well after planting. Sweet potatoes need consistent moisture during their first few weeks while the roots establish. After that, they are surprisingly drought tolerant once established.

Tending the Garden

Sweet potatoes are low maintenance once they are going. The main things to watch for are weeds, water, and vine length.

Keep the area around the slips free of weeds for the first month while they establish. Once the vines spread and cover the ground, they will shade out most weeds on their own. This is one of the real advantages of growing sweet potatoes. A well-covered garden needs very little weeding later in the season.

Water during dry periods, especially in the first six weeks. After that, the deep root system handles most drought on its own. If you get heavy rain, make sure water drains away. Sweet potatoes will not tolerate sitting in water.

The vines will spread across the ridges and can reach several feet long. Do not trim the vines. They are producing the energy that fills the tubers. If a section of vine touches bare soil, it may root at the nodes. This is normal and does not harm the plant.

Avoid high nitrogen fertilizer. Too much nitrogen pushes vine growth at the expense of tuber development. Sweet potatoes grown in the home garden rarely need fertilizer if the soil is decent. A light side dressing of compost early in the season is enough for most beds.

Harvesting and Storing

Sweet potatoes need a long growing season, typically ninety to one hundred twenty days from planting to harvest. Start counting from the day you planted the slips, not from the day the sprouts appeared.

In Zone 7a, plan to harvest in September or early October, well before the first frost. Exposure to even a light freeze will damage the tubers and they will not store well after that.

Here is how to harvest:

• Choose a dry day for digging. Wet soil sticks to the tubers and is harder to work with.
• Use a garden fork to loosen the soil around each plant. Start six to eight inches away from the vine crown and work outward. Pull the vine gently and lift the tubers from the soil.
• Handle the tubers carefully. Do not drop them. Do not use a knife to cut them free. Bruises and cuts will shorten their storage life.

Curing is essential for sweet potatoes. This is the process that heals surface wounds and converts starches into sugars, which improves both flavor and storage life.

Lay the harvested tubers in a single layer in a warm, humid place for ten to fourteen days. The ideal curing temperature is 80 to 85 degrees Fahrenheit with high humidity. A sunny porch, an unused bathroom with a humidifier, or a small room with a space heater and bowl of water will work. The goal is to get the skin to heal without drying out the tuber.

After curing, store the sweet potatoes at 55 to 60 degrees Fahrenheit in a dark, dry place. A basement or root cellar works well. Do not refrigerate them. Cold temperatures below 50 degrees will damage the tubers and cause them to harden and develop off flavors.

Stored properly, sweet potatoes will keep for four to six months. That means a garden planted in May can feed a family through the following spring.

Common Mistakes to Avoid

Planting in cold soil. This is the number one reason sweet potato gardens fail. Wait until the soil is warm. If you cannot wait, use black plastic mulch to warm the soil ahead of time and plant through holes in the plastic.

Starting slips too late. If you start slips in June and plant them in August, you are cutting your growing season in half and you may not get a usable harvest before frost.

Too much fertilizer. Sweet potatoes are tuber crops, not leaf crops. High nitrogen pushes vine growth and produces lots of leaves but few tubers.

Harvesting too late. A single frost ruins the storage quality. It is better to harvest a week early than to risk a light freeze.

A Crop Worth the Effort

Sweet potatoes are one of those crops that look intimidating at first because the growing method is unusual, but once you sprout your first batch of slips and watch the vines spread across a raised bed, it makes perfect sense. They produce a lot of food per square foot, they store without refrigeration, and they are genuinely easy to grow once you get past the slip-sprouting stage.

A single jar of water and a grocery store sweet potato in March will give you a full garden by June. That is a small ask for a crop that can feed you through the longest months of the year.

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— C. Steward 🍠