Sweet potatoes are traditionally grown in warmer places than Ireland but don’t be put off. New, hardier varieties mean that now you can grow sweet potatoes in places like Ireland and the UK. Follow the Snapshot and Snippets guide to growing sweet potatoes for bumper crops in a cooler climate.
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What are sweet potatoes?
Despite its name, the sweet potato is not a potato at all! This tasty root vegetable is related to the ‘Morning Glory’. You will certainly notice the family resemblance from their pretty trumpet-shaped flowers and vigorous spreading growth habit. Sweet potatoes come in a range of colours from orange to purple, and it’s not just the skins that are coloured – the flesh is too, so they look spectacular on the plate!
Better still they’re low fat, containing only 90 kcal per 100g, and loaded with vitamin C, vitamin A potassium, and fibre. The leaves and tips of young shoots can even be cooked as a spinach substitute and are delicious.
In fact, Sweet Potatoes are the healthy-eating superstars of the root vegetable world! Up there with Kale as a superfood
Which sweet potato to grow in your garden?
For Ireland/UK, which is zone 8 – I would recommend
- ‘Beauregard‘ is a bestselling variety, producing smaller tubers with a lovely salmon-orange flesh.
- “Bonita” Tan-skinned tubers with a purple cast, and unbeatably sweet, bright white flesh. Perfect for traditional potato dishes. Not available from supermarkets.
- “Burgundy” Uniform plants producing well-shaped, red-skinned tubers with sweet, burgundy-orange flesh. Not available from supermarkets.
Traditionally sweet potatoes have been grown from ‘slips’, but Sutton Seeds supply Super Plugs, which are well-rooted and actively growing, which give far better results! And I used them this year and got my first crop of Sweet potatoes.
Growing Sweet potatoes from slips
Unlike normal potatoes, sweet potatoes are normally grown from ‘slips’. These are the long shoots that have been removed from ‘chitted’ sweet potato tubers.
How to chit Sweet Potatoes
Place the sweet potato in a jar of water. You want to submerge most of the sweet potato while allowing a couple inches above the water. One of my sweet potatoes was so large it couldn’t fit well in the jar. Change the water occasionally to keep them from going mouldy. Place in sunlight. Soon the sweet potato will send out sprouts, or slips.
‘Slips’ don’t have roots, although sometimes there are signs of small roots beginning to appear. The roots will grow once the ‘slip’ has been planted. Whilst it is possible to grow your own ‘slips’ from supermarket sweet potatoes, most supermarket varieties are not sufficiently hardy to grow well in zone 8 – so crops are likely to be disappointing.
If you order slips when they arrive they will look withered, but place them in a glass of water overnight and they will quickly recover. The next day you can plant them up individually into small pots of organic multi-purpose compost. When planting sweet potato slips, it’s important to cover the whole length of the stem, so that it is covered right up to the base of the leaves.
Sweet potato plants are not hardy so you will need to grow them on in warm, frost-free conditions for 3 weeks or more until they are established. We put ours in the greenhouse. Warm, humid conditions will quickly encourage the slips to produce roots. Once they are well grown, and all risk of frost has passed, gradually acclimatise sweet potato plants to outdoor conditions prior to transplanting them.
Planting sweet potatoes
Sweet potatoes require high temperatures of 21-26°C (70-78°F), and their long stems need plenty of space as they have a vigorous growth habit. When growing sweet potatoes in zone 8, they are best planted in greenhouse borders, poly-tunnels or under cloches if you live in a cold area. In milder areas, they are well worth trying outdoors, planted through a sheet of black polythene to warm the soil and suppress weed growth. Cover them with frost fleece or plastic cloches – you’ll be amazed the difference that this will make to the temperature.
Grow sweet potatoes in full sun on fertile, well-drained soil. They are not particularly fussy but do prefer an acid or neutral soil. Plant sweet potatoes 30cm (12″) apart, leaving 75cm (30″) between each row. Where space is limited you can even grow sweet potatoes in containers or patio bags.
Growing sweet potatoes
Water sweet potato plants regularly. If growing your crop undercover, remember to open doors and windows during the day to keep your greenhouse or poly-tunnel well ventilated. Greenhouse and container crops will also appreciate a feed of general purpose organic fertilizer every two or three weeks.
Sweet potatoes have a vigorous growth habit and long sprawling stems. In the greenhouse, it may be useful to train the stems onto strings or trellis to keep them tidier. Outdoors you can simply spread the stems out around the plant. Pinch out the growing points of stems that extend beyond 60cm to encourage more lateral stems to develop. Don’t forget you can eat these leaves too which is a bonus.
Harvesting sweet potatoes
In late summer or Autumn, approximately 12 to 16 weeks after planting them, you will notice that the foliage and stems begin to turn yellow and die back. Now is the time to start harvesting your sweet potatoes, although they can be left in the ground longer if you prefer larger tubers. Make sure that you lift them before the first frosts though, to avoid the tubers being damaged by the cold. Lift them with a fork taking care not to bruise them.
We harvested our this week which is late but honestly they were still looking healthy so not until the threat of frost did I pull them out.
I love cooking with Sweet potatoes and love sweet potato fries here are some recipes you can try with sweet potatoes
- Awesome Leek and Sweet potato Soup
- Cheap and Cheerful Chilli Sausage, Potato, Bean Casserole
- Cottage pie with Sweet potato mash
- Slow-cooker vegetarian chilli
So why not try these tasty vegetables in your garden next year , with pretty flower , tasty leaves and delicious sweet potatoes , why wouldn’t you try them in a pot? Sign up for the Snapshot and Snippets newsletter and you can get a Free Gardener set with printables to help you grow your own vegetables and Quick grow guides. This weeks will be for Sweet Potatoes to add to your collection
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