Popular in the southern states, almost anyone can learn how to grow sweet potatoes.
Despite often being called a yam (Dioscorea sp.), the two vegetables are actually unrelated. Similarly sweet potatoes are not related to potatoes (Solanum tuberosum). Instead this pleasing edible is closely related to vining sweet potatoes, a popular colorful ornamental, and the morning glory (lpomoea tricolor) flower.
A tropical plant, sweet potatoes are hardy in USDA Zones 9 to 11. As the plant grows edible root tubers, which are in fact enlarged storage organs, form on the root. To enjoy a bountiful tuber harvest you will need to know how to encourage lots of healthy roots to grow. Because the vines root wherever they touch the ground correctly learning how to grow just a few plants pretty much guarantees you a large harvest.
Learning how to grow sweet potatoes is straightforward and rewarding.
Full of flavor and nutrients, versatile sweet potatoes are increasingly growing in popularity. If you have a little space to spare you too can learn how to grow sweet potatoes.
Sourcing Your Sweet Potatoes
If you are embarking on your how to grow sweet potatoes journey you should purchase slips from a nursery or respectable seller. Slips are new growth that sprouts from the ends of the root tuber. These are more likely to be healthy and successful.
In the following years you can use your own tubers to start fresh slips. However, to keep your crops healthy I would recommend purchasing new slips every couple of years.
Propagation from slips is the easiest way to get new plants because they rarely flower outside their native or preferred conditions.
How to Start Your Own Slips
To grow your own slips you will need to learn how to chit a tuber.
In the spring place a healthy sweet potato tuber in a warm place for a day or two. You can also soak the tuber in warm water overnight. This should be done roughly a month before your last predicted frost date.
You will also need a container large enough to comfortably hold your tuber. If you are aiming to get slips from a number of tubers, you will need a larger container. A deep seed tray comfortably holds two to three tubers.
Learning how to grow sprouts, or chitting, enables you to propagate your own sweet potatoes.
Evenly mix potting soil and sand together. Place a layer of this material, roughly two inches thick, in your chosen container. Put your potatoes horizontally in the container and cover with soil. Don’t worry if the top of the tuber is visible through the soil.
Keep the soil warm and moist. In a few weeks slips, or green shoots, will emerge. On average each average sized tuber produces around 6 slips.
Allow the slips to grow to about 4 inches in length before carefully breaking them from the plant.
Each slip should have its own root system. If this isn’t the case root the slip in a glass of fresh, chlorine free water. Submerge the bottom few inches of the slip, allowing the leaves to sit well above the water level. Roots emerge within about a week.
The slips can be planted out once the last frost date has passed and the soil has warmed to at least 60 ℉.
How to Start Slips from Vine Cuttings
In areas with short winters learning how to start slips from vine cuttings can be useful.
Before the first frost, cut off a vine about 6 inches from the tip. Place the cutting in a glass of fresh water. Once roots have formed, plant in a pot filled with fresh potting soil.
Keep the plants in a light location until you are ready to plant out.
Selecting a Variety to Grow
If you are just embarking on your how to grow sweet potatoes journey, or want to try a new variety, here are some of the most reliable:
- Georgia Jet is a fast maturing variety, ideal for growers in cooler climates. Producing red skinned tubers with an attractive orange flesh, mature tubers are ready for harvest in about 90 days.
- Centennial is another fast maturing variety, again tubers are ready for harvest in around 90 days. It is also a pleasingly robust and disease resistant variety.
- Beauregard is a popular cultivar prized for its pale red tubers that have a dark orange flesh. The plants take about 100 days to mature fully.
- Patriot is a popular choice for organic gardeners because of its pest resistance.
- Murasaki is an unusual cultivar which is grown for its distinctive white flesh. These sweet potatoes also have a distinct nutty flavor.
- Bush Porto Rico is a compact plant, ideal for containers and smaller spaces. It is prized for its heavy yields. These sweet potatoes take about 110 days to mature and are copper in color with an orange flesh.
Identify a variety that not only appeals to you but is also able to grow in your climate.
Whether you are ordering slips or chitting your own, aim to get the slips into the ground as soon as possible. Most varieties require 90 to 120 days to mature. If you are growing in a cooler climate, select from amongst the quick growing varieties.
How to Create the Ideal Growing Conditions
Once you have selected your tuber the next step on your how to grow sweet potatoes journey is creating the ideal growing conditions.
Luckily, for the home gardener, these are surprisingly resilient little tubers. They handle the heat and drought conditions surprisingly well. However the plants struggle, and can even fail completely, if exposed to even the lightest frost.
Gardeners in cooler climates are advised to grow quick maturing varieties. You can also try to extend the growing season for a little longer by using floating row covers. Agfabric Floating Row Covers trap heat close to the soil, keeping your plants warm while temperatures begin to fall. The covers are also permeable, meaning that while heat is trapped moisture and sunlight can still filter down to the roots.
Remember that sweet potatoes are a root crop. This means that you should pay close attention to the condition of your soil. Use a soil test kit if you don’t already know your soils makeup. The pH level should be between 6.0 and 6.5. Soil slightly outside this range is okay, but avoid planting in extremes.
A sandy or loamy soil that is well draining is ideal. It should also be rich in nutrients. Try to avoid soil that is too rich in nitrogen, or amend it before planting. Nitrogen rich soil encourages lots of vigorous vine growth but at the expense of a large harvest.
Clay soils can be improved. However if the soil is particularly problematic, try growing in a container or raised bed. Raised beds are often filled with loamy, loose soil. This makes them the ideal container for sweet potatoes.
Work in organic matter, such as fresh compost about two weeks before planting to further enrich the soil.
The soil temperature must be between 60 and 85 ℉ for healthy growth to begin. The air temperature should be between 65 and 90 ℉.
Take the time to properly prepare the soil before planting. This helps the plants to grow strong and healthy.
These are light and warmth loving plants. While full sun positions are often preferred if you are growing in a particularly warm climate try to plant somewhere with a little afternoon shade. This helps to shield the growing plants from the extreme heat of the sun.
If space is really at a premium you can try to train the growing vines up a trellis. This frees up more soil space for other plants.
How to Plant Your Sweet Potatoes
Dig a hole in the prepared soil large enough to hold the slip. When positioned in the hole, the leaves should sit above the soil level.
Plant the slip in the center of the hole and gently firm down the soil, being careful not to compact it. Water well.
Space the plants 12 to 18 inches apart. Large sprawling varieties may require at least 24 inches of growing space. Rows should be spaced 3 to 4 ft apart. This gives the vines lots of room to spread without danger of overcrowding.
Mulch around the plants to help improve moisture retention. Organic mulches such as grass clippings or bark are ideal.
Keep the soil moist until the roots have established themselves. New growth is a clear sign that the slips have settled and the roots are established.
In cooler climates, to encourage the plants to grow, mound the soil about 8 inches high and plant in the mounds. This helps the soil to warm more quickly. Soil in raised beds or containers is often quicker to warm that garden soil.
Planting in Containers
If you want to learn how to grow sweet potatoes in containers, the process is largely the same as growing in raised beds or the ground. Just don’t plant too many slips in one pot. Overcrowding the plants decreases the number of tubers they produce. Allowing the plants lots of room to spread increases the yield significantly.
Use large containers with lots of drainage holes. The containers should be filled with well draining potting soil. Before planting mix a slow release fertilizer into the soil so that it is spread evenly throughout the pot. Plant as described above.
If you are learning how to grow sweet potatoes in a cooler climate, try planting in large pots indoors in early spring. The pots can then be moved outside in the spring as temperatures warm up. Placing the pots on a Plant Caddy enables you to easily move them around your home and garden. This is a great way to extend short growing seasons. You can also grow sweet potatoes in pots in a greenhouse or cold frame.
How to Care for Sweet Potatoes
Once planted care is pleasingly straightforward. When the slips are newly planted, keep the soil weed free. As the vines grow weeds will struggle to emerge. Try not to cut the vines back unless it is absolutely necessary. If space is an issue, try growing compact or bush varieties.
Learning how to correctly care for your plants helps to maximize your yield of sweet potatoes.
How Often Should I Water?
Even though the plants tolerate drought well your harvest will be larger if they are watered regularly and not allowed to suffer from stress. Allowing foliage to wilt impacts negatively on root development.
Water regularly if it doesn’t rain. While the amount of water the plant requires varies depending on the growing conditions, on average as the plants grow they require about 1 inch of water a week. Use a watering can to water evenly around the entire plant.
About 3 weeks before harvesting cease watering. Overwatering this close to harvest may cause tubers to split.
Do I Need to Fertilize?
These are not heavy feeding plants. In fact over feeding can lead to an excess of foliage and underdeveloped tubers.
Composting the soil before planting should give the plants all the balanced nutrition that they need. You can also apply organic liquid fertilizer to the soil before planting.
Common Pests and Problems
An important part of knowing how to grow sweet potatoes is learning how to identify and deal with common problems.
Underground pests are the most frustrating. Root knot nematodes and wireworms can happily eat their way through your tubers without you realizing it. Regularly inspect your plants to make sure that they are healthy. Stunted growth and yellowing foliage are signs that there may be a below ground infestation. Planting cover crops or adopting a simple form of crop rotation can help to keep the soil healthy.
Flea beetles can target the foliage creating scores of tiny holes. While unsightly, healthy vines are able to withstand attacks from this irritating little pest.
Regularly check the foliage for signs of disease or infestation.
Sweet potato weevils like to puncture the stems and tubers, filling the plants with their eggs. After hatching the eggs grow into destructive larvae that feed on the roots, causing them to rot. A difficult pest to combat crop rotation can help to keep soil healthy. Affected plants should be destroyed.
These crops can also suffer from scurf. This is a common problem that causes black spots to emerge on tubers. It doesn’t affect the crop, simply peel away the affected skin.
While these are a low maintenance, generally problem free crop, if you are embarking on your how to grow sweet potatoes journey and want to minimize potential problems grow disease resistant varieties. This coupled with planting healthy slips in favorable conditions will help to ensure a healthy, problem free yield.
How to Harvest
The foliage can be lightly harvested throughout the season for nutritious green. However you shouldn’t harvest too heavily, this can have a detrimental effect on the size of the yield and may stop the plant from growing.
Sweet potatoes are ready for harvest around 3 to 4 months after planting. The exact time frame depends on the cultivar and the growing conditions.
Dig up the tubers just as the foliage starts to yellow. If an unexpected frost hits, the foliage may suffer but the tubers should still be fine. Don’t allow them to sit in the ground for too long after the foliage, or tops, begin to die back otherwise they may start to rot.
To prevent crops from becoming damp, harvest on a dry, sunny day. Carefully dig down until you reach your tubers. Be careful, the tubers grow close to the surface and their tender skin is easily bruised or damaged.
Save a couple of the healthiest tubers for chitting in late winter or early spring. These tubers should be lifted before the first frost. They can be stored in peat or vermiculite in a cool, dry dark place such as a garage or basement.
How to Cure Tubers
If you want to keep or store the tubers you will need to cure them. To do this dry the tubers in the sun for a few hours before moving them to a dry, well ventilated place, the temperature should average between 85 and 90 ℉.
After 10 to 15 days the tubers will have dried sufficiently. They can now be stored for several months in a suitable place, the temperature should be around 55 ℉ and the humidity 75 to 80%.
Take care when harvesting not to damage the tubers.
Learning how to grow sweet potatoes is a satisfying and refreshingly straightforward process. Easy to grow and care for, these tubers are great to eat and packed full of nutrients. With a little time and care, once you know how to grow sweet potatoes you will be able to grow them every year as part of your annual vegetable harvest.
Jen is a master gardener, interior designer and home improvement expert. She has completed many home improvement, decor and remodeling projects with her family over the past 10 years on their 4,500 sf Victorian house. She is also a passionate farmer who keeps goats, chickens, turkeys cows and pigs on her farm, and an instructor for her community’s Organic and Sustainable Farming project.