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Growing Sweet Potatoes at Home

Publication Number: P2784
View as PDF: P2784.pdf

Growing Sweetpotatoes at Home

The sweetpotato is a tropical, warm-season crop originating from South America. It is a member of the morning glory family (Convolvulaceae) and is grown for its enlarged storage roots (Figure 1).

Photograph of sweetpotato storage roots. Sweetpotato storage roots are the part of sweetpotatoes that we eat. These sweetpotato storage roots are connected with one another and are buried below the ground.
Figure 1. Sweetpotato storage roots.

Sweetpotatoes are broadly divided into two categories: those with moist flesh and those with drier flesh. Moist-flesh varieties are often referred to as “yams,” but sweetpotatoes and true yams are botanically different. Yams are grown for their tubers, originate from West Africa, and are from an entirely different plant family than sweetpotatoes (Dioscoreaceae).

Sweetpotatoes make an excellent addition to Southern gardens and provide gardeners with a delicious source of fiber, vitamins, minerals, and complex carbohydrates. With some help, you can grow sweetpotatoes at home.

Site Selection

Sun Exposure

Sweetpotato plants require full sunlight to fully develop. Plants should receive at least 8 hours of full sun each day. Sweetpotato plants are vines, and they trail along the ground. In a mixed vegetable garden, avoid planting sweetpotatoes near taller vegetable plants with more upright growth habits. Taller plants typically block sunlight from the low-growing sweetpotato vines. If space is limited, plant sweetpotatoes on the south or west side of taller plants to allow for more direct sunlight.

Soil

Well-drained, sandy, or loamy soils provide the best environment for storage roots to develop. Planting sweetpotatoes in heavy clay or rocky soil will result in misshapen sweetpotato roots. Soil that does not drain well may result in lower yields and rotten sweetpotato roots. Sweetpotatoes are fairly tolerant of a wide range of soil pH but will grow best in soils with a pH of 5.5 to 6.5. Sweetpotatoes do not require large quantities of organic matter in the soil but do benefit from soil with organic matter. If you add animal manure to the soil, be sure to add it well before planting to allow for decomposition.

Photograph of a sweetpotato garden. This photograph is centered on the slips. Someone is cutting the slips, leaving 1 inch from the surface of the soil. The person is holding the bunches of slips that they have already cut.
Figure 2. Sweetpotato slips are cut 1 inch above the soil surface from slip production beds.

Production

Starting Material

The starting material for sweetpotatoes is different from most other home vegetable garden crops. Sweetpotatoes are produced from vegetative stem tip cuttings, or “slips.” Slips are produced from sprouted sweetpotato storage roots saved from the previous year’s crop. Slips may or may not have roots when they are cut. A good sweetpotato slip should be firm, green, and 8 to 12 inches long, preferably with one or two leaves (Figure 2).

You can produce slips at home or purchase them from a reputable vendor. Information about sources for sweetpotatoes and sweetpotato plants is available from the Mississippi Sweetpotato Council at www.mssweetpotato.org.

Growing Your Own Slips

Eight weeks before you plan to plant slips, place smaller sweetpotato roots (approximately 11/2 inch wide) from the previous year’s crop into hotbeds and cover with 1 to 2 inches of soil. You can also plant sweetpotato roots in raised beds, cover with 1 to 2 inches of soil, and cover the entire bed with black or clear plastic mulch. Plastic mulch should contain a 2-inch ventilation hole every 4 linear feet of plant bed. Plant beds should remain between 75 and 85°F. Remove the plastic mulch when shoots begin to emerge from the soil (approximately 2 to 4 weeks after bedding). Slips are ready to cut when the growing point of the shoot extends 9 to 13 inches above the soil surface.

Planting

Sweetpotatoes should be grown in ridged rows 12 inches wide and 8 to 10 inches tall. Plant after soils have warmed and all danger of spring frost has passed (Figure 3). In Mississippi, sweetpotato slips can be transplanted from early May through June. Plant slips with the cut end down 4 to 5 inches deep and 9 to 15 inches apart. Rows should be 3 to 4 feet apart. Planting slips farther apart in a row will often provide a gardener with an earlier harvest or larger sweetpotato roots.

Photograph of sweetpotatoes growing in rigid planting beds. These sweetpotatoes sit on a plant bed that is a foot in width. There are rows between each plant bed. These alternating rows are deeper into the ground than the surrounding plant beds.
Figure 3. Sweetpotato plants growing in ridged planting beds.

Fertilization

Proper nutrient management begins with a soil test. Test results will include recommendations for fertilizer application rates. In the absence of a soil test, apply 5-10-10 fertilizer at a rate of 15 to 30 pounds per 1,000 square feet. Incorporate prior to ridge formation and planting.

Water

Sweetpotatoes are tough plants and are generally considered to be drought tolerant; however, the best quality and greatest quantity of sweetpotato storage roots are produced when plants receive timely and sufficient watering. Plants should be watered immediately after they are transplanted in order to allow roots to form on slips. Maintain even soil moisture during the first two weeks after planting. After plants are established, sweetpotatoes should receive approximately 1 inch of rainfall or irrigation per week.

Pests

Like most garden plants, sweetpotatoes have their share of pests. The best way to control weeds in the home garden is by shallow hoeing, hand removal, and mulch. A layer of mulch 1 to 2 inches thick should suppress most weed species and help maintain even soil moisture during the growing season. Using herbicides on sweetpotato plants in a home garden is generally not recommended as many broad-spectrum herbicides can injure sweetpotato plants.

In south Mississippi, sweetpotato weevils can be problematic. Throughout the state, beetle larvae that burrow into the developing sweetpotato roots and caterpillars that eat sweetpotato foliage can also threaten sweetpotatoes. In addition, deer find sweetpotato leaves to be very palatable and will graze on sweetpotato plantings if there is no barrier. Deer repellents and fences can deter deer but may not eliminate feeding completely.

Diseases in sweetpotatoes are not common in home gardens. You can minimize disease by cutting sweetpotato slips instead of pulling them, acquiring plant material from reputable vendors, and rotating crops to avoid planting sweetpotatoes where they have been grown within the last two years. For more information on weed, insect, and disease control in sweetpotatoes, consult your county Extension office.

Harvest

Unlike most crops, sweetpotatoes never truly ripen or reach a stage of maturity. Young sweetpotato storage roots are formed within the first two weeks of planting and continue growing larger. Sweetpotato varieties vary in days to maturity, but most range between 90 and 120 days. Sweetpotatoes should be harvested in the late summer to early fall before soil temperatures drop below 60°F. Carefully place a shovel or garden fork into the ground far enough away from where the vine enters the ground to avoid cutting through the sweetpotato storage roots. Use the shovel or fork to lift up each individual hill. Exercise care not to damage the sweetpotato skin excessively while digging and handling them. Excessive skinning or abrasion will shorten the time roots can be stored and may cause roots to spoil or shrivel (Figure 4). Harvesting sweetpotatoes when the soil is dry will result in increased skinning and should be avoided if possible.

The sweetpotato has a skinning effect, where parts of the skin are removed. Where the skin once was, there is a dark brown effect.
Figure 4. Skinning injury can occur during harvest.

Curing

Cure sweetpotatoes immediately after harvesting them. To cure them, place them in an environment with temperatures of 80 to 85°F and 85 to 90 percent relative humidity for 7 to 10 days. Curing helps to heal wounds that occur during harvest, preventing shriveling and reducing the risk of rot during storage. Curing also makes the sweetpotato more palatable by converting starches to sugars and improving aroma and texture.

Storage

Under the right conditions, properly cured sweetpotatoes can be stored for months. Sweetpotatoes should be stored in a dark, cool place. Temperatures should remain between 55 and 60°F. Remember that sweetpotatoes have tropical origins, and a raw sweetpotato should never be stored in the refrigerator. When stored below 55°F for extended periods of time, roots can experience chilling injury, resulting in hard cores and altered taste when they are cooked. If roots are stored above 60°F for extended periods, sprouts may begin to appear from the top of the root.

Table 1. Sweetpotato varieties

Variety

Days to Maturity

Skin Color

Flesh Color

Yield

Notes

Beauregard

90–100 days

light rose

moderately deep orange

high-yielding

leading commercially grown variety in Mississippi

Centennial

90–100 days

orange

deep orange

variable depending on soil-borne disease pressure

susceptible to soil pox disease; avoid soils that have resulted in little or no storage root formation in the past

Covington

110–120 days

rose

orange

high-yielding

root shapes tend to be round to blocky when grown in heavier soils

Okinawan

110–130 days

dark purple

bright purple

lower yielding than newer varieties

unique and vibrant flesh color

Jewel

110–120 days

copper

orange

variable depending on soil-borne disease pressure

avoid soil with a history of soil-borne diseases

Murasaki-29

100–110 days

dark purple

cream-white

yields in north Mississippi have been below expectations

flesh has a drier texture than typical sweet potato varieties and a mildly sweet, nutty flavor

Nancy Hall

100–110 days

light orange

creamy orange

lower yielding than newer varieties

an old favorite

O’Henry

90–100 days

cream

white

acceptable yield

a mutation of Beauregard

Evangeline

90-100 days

rose

deep orange

high-yielding

high sugar content

Photos courtesy of Mark A. Hall, Research Associate, Pontotoc Ridge-Flatwoods Branch Experiment Station, Plant and Soil Sciences.


Publication 2784 (POD-01-22)

Revised by Lorin M. Harvey, PhD, Assistant Professor, North Mississippi Research and Extension Center, Plant and Soil Sciences, and Mark W. Shankle, PhD, Research Professor, Pontotoc Ridge-Flatwoods Branch Experiment Station, Plant and Soil Sciences, from a previous edition by Stephen L. Meyers, PhD, former Associate Extension/Research Professor, and Mark W. Shankle.

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Sweet Potatoes

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