Sweet potatoes are grown more often in southern regions because they require at least four months of warm temperatures, though there are varieties that will grow in northern gardens, too. They are surprisingly easy to grow and just a few plants can produce a generous harvest. Here’s how to plant, grow, and harvest delicious sweet potatoes in your garden.
In warm climates, many gardeners plant sweet potatoes about a month after the last spring frost, when both the air and soil are dependably warm. There are bush types and vining types.
Sweet potatoes aren’t started by seed like most other vegetables, they’re started from slips—small rooted pieces of tuber which are sliced right off the sweet potato.
How To Grow Sweet Potatoes
Sweet potato plants are fast-growing vines that cover the ground.
Originally they come from Central and South America, which means they are a warm-weather vegetable. You need a long warm season to grow good sweet potatoes.
There are sweet potato varieties with red, yellow, and white tubers. The red ones have the highest carotenoid content and have become the most popular variety. But all sweet potatoes are very nutritious in general, especially if you use the leaves and shoots, too.
You’ll be hard-pressed to find a plant that produces more nutrition per square metre than the humble sweet potato!
Planting
Sweet potatoes will grow in poor soil, but deformed roots may develop in heavy clay or long and stringy in sandy dirt. To create the perfect environment, create long, wide, 10-inch-high ridges spaced 3½ feet apart.
Work in plenty of compost, avoiding nitrogen-rich fertilizers that produce lush vines and stunted tubes. In the North, cover the raised rows with black plastic to keep the soil warm and promote strong growth.
It’s best to plant root sprouts, called slips, available from nurseries and mail-order suppliers. (Store-bought sweet potatoes are often waxed to prevent sprouting). Save a few roots from your crop for planting next year.
About six weeks before it’s time to plant sweet potatoes outdoors in your area, place the roots in a box of moist sand, sawdust, or chopped leaves in a warm spot (75 to 80 degrees). Shoots will sprout, and when they reach 6 to 9 inches long, cut them off the root. Remove and dispose of the bottom inch from each slip, as that portion sometimes harbors disease organisms.
Sweet potatoes mature in 90 to 170 days and they’re extremely frost-sensitive. Plant in the full sun three to four weeks after the last frost when the soil has warmed. Make holes 6 inches deep and 12 inches apart. Bury slips up to the top leaves, press the soil down gently but firmly, and water well.
Soil
Plant in a soil high in organic matter and then leave them alone. To give them a head start, sweet potatoes are often planted in raised rows, about 8 inches high. This helps the soil warm faster and keeps them well-drained. If you are gardening in a cooler climate, spreading black plastic on the soil will also help it warm faster.
Water
Once established, sweet potatoes will tolerate growing in dry soil. It’s best to keep it evenly moist with an inch of water once a week. Don’t water your sweet potatoes during the final 3 to 4 weeks prior to harvest in order to keep the mature tubers from splitting.
Fertilizer
Feeding sweet potatoes tend to produce just foliage. You can add compost to the beds before planting the sweet potatoes.
Pests/Diseases
- Flea beetles
- Sweet potato scurf
- White blister
- Fungal leaf diseases (Alternaria leaf spot and blight, Botrytis)
- Stem rot