Sweet potatoes (Ipomoea batatas) are easy and rewarding to grow with a little garden space. The plant also produces an attractive vine while the sweet potatoes are developing underground. Sweet potatoes can be successfully grown in a home garden when planted in-ground or in containers, just provide them with plenty of sunshine and room to grow. Read on to learn all about growing sweet potato in your garden.
Differences between Sweet Potato and Potatoes
You might wonder what the differences between sweet potato and normal potatoes are. Sweet potatoes (Ipomoea batatas) are only distantly related to normal potatoes (Solanum tuberosum) by being in the same taxonomic order, but as you can see from their scientific names, they are practically different plants (different families). Sweet potatoes are from the same family as the morning glory flower, while potatoes are in the nightshade family, which includes tomatoes and peppers. These are plants that produce a compound called solanine, which some people can be allergic to. Sweet potatoes are described as tuberous roots, while potatoes are just tubers. Both have a long history of cultivation by man.
Planting Location and Soil Preparation
Select a planting location that receives at least 6 hours of direct sun each day. Though the actual sweet potato grows underground in the dark, the above-ground vine needs sunshine to create energy to send down into the developing potatoes.
Sweet potatoes need loose, sandy soil for the best production. The loose soil will allow the potatoes to develop without restriction and promote good air and water circulation. Avoid clayey soil as it restricts the size of the potatoes. The soil pH should neither be too acidic nor too alkaline. Generally, a soil pH of 5-6.5 (slightly alkaline) will be adequate for good growth.
Test your soil prior to planting. If you are applying NPK fertilizer, apply some phosphorus and potassium initially, while nitrogen can be added a few weeks after planting when the slips spread outside of the bed. Refrain from adding excessive nitrogen to sweet potatoes. Generally, a concentration of 11-12 ounces per 1000 square feet of soil should suffice.
Prepare the soil of your home garden by digging it out to the depth of 12 inches in the location where the sweet potatoes will be planted. Mix the removed soil with sand at a 50-50 ratio. You can also use compost for organic growing in place of standard NPK fertilizers. Mix in 1 gallon of compost per wheel barrel load of the soil/sand mixture, along with sand. Return soil mixture to garden and smooth it out with a hoe.
Sweet potatoes can also be grown in containers that are at least 12 inches deep. Create a 50-50 mixture of potting soil and sand, and mix in a cup full of compost per container. Place container in full sun location. The number of sweet potatoes you can get from growing them in containers would be somewhat limited though.
How to Plant
Plants are started from “slips” (not seeds) but don’t be in a rush to plant them. Slips are sprouts that are grown from a mature sweet potato. If you have a sweet potato, you can also grow such slips. To get ready slips, simply cut a sweet potato in half and submerge it in a bowl of water (half below and half above the water level). In a few weeks, the sweet potato will develop numerous leafy slips or sprouts which can then be detached (pull them out carefully from their bases) and in turn soaked in shallow water (bottom half) to induce them to root. Roots should develop from the slips within a week or so. Your slips can then be planted in the garden.
Bear in mind, sweet potatoes need warm soil and warm air temperature to grow, so wait until late spring before planting the slips. Sweet potatoes need some space to grow, so leave enough space between the slips, about 1.5 feet or 18 inches apart in a row, and 3-4 feet between each planted row. Bury them in the soil up to the top set of leaves.
Water the newly planted slip well and apply a layer of organic mulch, like straw. Keep soil moist during the first two weeks until plants become established, then water less frequently.
Keeping an Eye on Pests
Sweet potato is generally hardy with few pests, but there are a number of pests that feed on the roots or the plant itself. Some of these include the sweet potato weevil, banded cucumber beetle, and silverleaf whitefly. Among these, the sweet potato weevil is considered the most serious pest of sweet potato. Insecticides whether organic or not, are normally applied to the soil or the plant during mid-season, but these should be used sparingly.
Other biological control methods include crop rotation and the use of predatory ant colonies that feed on these pests being released into the planting beds. You may also consider planting companion plants nearby your sweet potato. Suitable companion plants include dill, oregano, thyme, summer savory, beets and parsnips.
Harvesting Sweet Potatoes
Harvest just before the first frost in autumn. Use a hand-held trowel to work around the plant to free the sweet potatoes from the soil. Brush off loose soil and lay in a single layer to dry overnight. After they are dry, you can proceed to “cure” them.
Curing and Storing
Sweet potatoes get their sweetness from being cured and stored properly. After the initial 24 hours drying time, place the potatoes in a single layer in a warm room for around 10 days to toughen the skins. Curing sweet potatoes is needed to heal the tubers from any damage during harvesting, but mainly it is to induce them to convert their starchy content into sugary content.
The ideal recommended temperature is 80-85 degrees Fahrenheit (27-29°C) with a humidity of around 80-90%, but for home growers, you can simply cure the potatoes by placing them in plastic bags with some holes and leaving them on a sunny window sill.
After the curing period, wrap each sweet potato in newspaper and store in a dry, cool location that will remain around 60 degrees Fahrenheit (15.5°C). Normally, they are stored like this for up to 6 weeks, during which time they should further increase in sweetness.
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