Nothing makes a holiday dinner more special than a beautiful casserole dish filled with delicious baked sweet potatoes. While regular potatoes are grown from planting sections of the potato in the ground, sweet potatoes are grown from slips, or the sprouts of the sweet potatoes.
Getting started is easy, but timing is very important. You can’t plant the slips in the garden until the soil warms up to at least 65 degrees F., and all danger of frost has passed. A rule of thumb is to get the slips started 30 to 40 days before your last frost date.
Start slips by purchasing large firm sweet potatoes at the store. Sweet potatoes are not usually treated with chemicals to prevent eye formation like regular potatoes, but buy organic if available. Be very careful when handling sweet potatoes as they bruise easily. Push three of four toothpicks into the side of the sweet potatoes and submerge half of the potato into a jar of water or other container. Place the jar in a bright area, but out of direct sunlight, and keep the water level constant. After a few days, the potato will begin to sprout roots, then green sprouts. If the sweet potato begins to rot and smell, throw it away and start over with a new potato.
When the sprouts get 4 inches long, gently twist them off the potato. Pull with a downward motion so you will get the “heel.” These are your slips. Set the slips in another jar of clean water so the bottom halves are submerged. When the roots are 2 inches long, the slips are ready to plant. If you started too early, and there is going to be more than 2 weeks before you can get them in the ground, plant them in damp potting soil to hold them over until planting time.
If you are buying sweet potato slips already started, buy from a supplier that guarantees the roots are certified disease-free. The roots will probably arrive in sad shape, so immediately upon arrival place them in water and allow roots to begin growing before planting them in the garden. Some tried and true sweet potato varieties are Beauregard, Georgia jet, Jewell, Vardaman and Centennial.
Sweet potatoes do not need lots of fertilizer, just average garden soil amended with lots of compost. The compost or manure must be well decomposed or it makes scabby spots on the sweet potatoes. They must be grown in a well-drained location in full sun for best sweet potato production. Bury the slips 4 inches deep and 18 inches apart. Because the vines get so large, rows should be at least 4 feet apart. Gently tamp down the soil around the slips and water to settle the soil around the roots. Water the sweet potato plants while they are young as often as once a week by deeply soaking the area where they are growing. Once the vines cover the ground, add water only if the vines are wilted before noon. They will naturally wilt in the heat of the afternoon, but should recover by sunset. Sweet potatoes like it hot and dry. Withhold water completely the last 3 weeks before harvest. If you give the plants too much water, especially in the last few weeks before harvest, the potatoes will split and the harvest will be disappointing.
Sweet potatoes are ready to harvest in 100 to 150 days. Test a few by gently digging into the soil with your hands to see if they are ready. Sweet potatoes are ready when you think they are the right size, but don’t wait past the first frost date to harvest because frost can ruin the crop. Gently dig them from the ground after cutting back the vines. The storage period is drastically shortened if the tubers are bruised, so handle them gently. Allow the freshly harvested sweet potatoes to cure by setting them in the sun for 3 hours then moving them to a dry warm location with a temperature of 80-85 degrees F. Gently place them in a single layer on a dry surface and let them cure for 10 days. They can be stored in a root cellar where the humidity is high and the temperature is 55-60 degrees F.
FYI: Sweet potatoes are not the same as yams. Yams grow in the tropics and are not related to sweet potatoes that come from the morning glory family. Sweet potatoes plants make attractive vines for container and hanging baskets.
ABOUT THE AUTHOR
Jim Gober is a gardening writer, farmer, florist and landscaper from Central Texas. His gardening articles appear across the Internet and in numerous periodicals. He is a Certified Texas Nursery and Landscape Professional and Master Gardener. His website is www.biglump.com