How to Grow Sweet Potato

Sweet potatoes are in fact not a potato at all! Our American friends call them yams but they are a member of the morning glory family rather than the potato family.

Nutritionists love sweet potato because it is high in vitamins A, B6, C, manganese, magnesium, potassium, fibre and antioxidants whilst also being low in fat and calories with a low glycemic index. They have been associated with reduced risk of cancer, good digestive health, eye health, immune function support, managing type 2 diabetes, heart health, liver protection, brain and nervous system support and more.

They are relatively easy to grow so if you love sweet potatoes, you definitely want to have a go at growing them.

When to grow sweet potatoes

Sweet potatoes like warmth. In warmer tropical or subtropical areas, you may be able to grow it most of the year. If you are in a cooler climate, you are best to plant it in spring as the weather is starting to warm up, and that way you’ll have the full length of your warmer weather for it to grow and thrive.

Sweet potato varieties

Would you believe there are over 7000 different sweet potato varieties around the world? You could eat a new one every day and still take more than 19 years to try them all! Some of the most popular varieties include:

· Beauregard – large tubers with orange flesh and red/orange skin. This is a disease resistant variety that is firm and sweet

· Northern Star – a double-skinned variety with tubers that have white flesh and red skin and a sweet, nutty flavour

· Eclipse – another disease resistant variety, these tubers have a purple flesh with a white skin and are slightly sweeter than other varieties

· Bayou Belle – this variety has purple/red skin and orange flesh and will remain firm after cooking unlike other varieties that can become mushy

How to grow sweet potatoes

Like many tubers, sweet potatoes can be grown by simply taking a tuber (that you’ve got from a friend or even the shop) and planting it in the soil. Eventually the tuber will sprout and grow like crazy. You can also put the tuber in a container with some water and around a month later, it will sprout. These sprouts are called slips. Alternatively, you can take existing slips from a friend’s plant and put them into a pot with some soil or straight into a garden bed you’d like to grow them in.

No matter how you decide to propagate, sweet potato loves to be in loose, crumbly soil rich in organic matter. Planting them in hard or clay heavy soil will mean a stunted crop with small tubers. They also hate to be water logged so you need to ensure you have good drainage in the soil.

Raised garden beds are perfect for growing sweet potatoes in – it ensures good drainage, will contain them from spreading too far, and you can fill them with quality soil. Birdies garden beds [use code SSMEbird for a 5% discount. (If you’re in the USA, click here and use code SSME2020 for 5% off)] are Mark’s raised beds of choice. Sweet potatoes enjoy full sun but will do just fine in partial shade. Be sure to water them regularly for big plump tubers.

How long does sweet potato take to grow?

Most varieties reach maturity in around 85-120 days. You can start to check your tubers periodically from around the 85 day mark to see how they are progressing, and you may like to harvest a few as you go.

When and how to harvest sweet potatoes

When you start to see foliage yellow and die back, that’s a good sign that they are ready to harvest. You want to start by ripping out all of the top foliage so you can see what you are working with underneath. Then carefully dig out the tubers doing your best to avoid damaging the tubers. You may like to leave the tubers out in the sun for a day or two to dry off any areas where fresh flesh has been exposed, as this will help the tubers to last a little longer.

Sweet potato pests and diseases and how to control them organically

Root Knot Nematode

A microscopic organism that loves to eat roots, root knot nematodes are common on carrots, tomatoes, potatoes, sweet potatoes, grapevines, and beans. You won’t know you’ve got a problem with this until you go to harvest your sweet potatoes and you find a tuber that looks like a string of knots. The worst thing is there’s not much you can do to treat the problem – the best plan of attack is to salvage what you can and burn the remainder of the plants to ensure you don’t spread it any further. You definitely don’t want to be composting these nasties! Ensure you rotate your crops and don’t plant any plants susceptible to nematodes in that bed for at least 3 years. Companion planting marigolds or asparagus may help prevent this problem as the roots of these plants secrete exudates that can help eradicate them.

Sweet Potato Weevil

Small weevils lay eggs on the vine of your sweet potatoes and when they hatch, the larvae bore down into the sweet potatoes causing damage to the tuber which can then rot. As with many

pests, prevention is better than any cure. Ensuring you use a good organic mulch can reduce weevil movement and stop them being a problem. Alternatively, there are pheromone bait traps you can buy to reduce numbers. Ants, spiders and earwigs are natural predators of weevils too.

Spider Mites

Spider mites are tiny insects that live in on the undersides of leaves where they feed off plant cells and spin fine protective silk webs. They can be very difficult to see as they are so small, and you will likely spot the damage they are doing to your plant before you see the insects themselves. Look for yellowing foliage or leaves with yellow spotting. Controlling your infestation could be as simple as using a high-pressure hose nozzle and spraying them off the plant and keep spraying the leaves regularly as spider mites like hot, dry environments. There are a number of different home remedies that you can try too including soapy water with cooking oil (called white oil-here’s our recipe), lemon juice and water, alcohol and water, or pepper spray with garlic and onion. A quick google search will give you the ratios you’ll need for each one. Alternatively, neem oil is another option to help rid your plants of spider mites.

Mark’s top tips for growing sweet potatoes

Before you plant your sweet potato tubers or slips, use a garden fork to loosen the top 30 cm or 12 inches of soil and fertilise with good quality compost initially. Don’t fertilise regularly, as over-fertilising can result in low tuber numbers and lots of green growth above the soil. You may also want to check out Mark’s video “5 Top Tips How to Grow a Ton of sweet potato in one container or garden bed” for more tips.

Do you have any tips or questions about growing sweet potatoes?

Mark and the Self Sufficient Me team love hearing about your growing success so why not join our forum to let us know how you went growing sweet potatoes?

If you had some trouble growing sweet potatoes or simply want to pick Mark’s brain about your self-sufficiency goals or projects, you may want to consider becoming a patreon for exclusive content and email access for less than a restaurant meal each month!