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Sweet Potato Tips & Advice

Who would have thought you could grow them in your own garden? Well this unusual vegetable, considered by many as tropical has been successfully grown here at Kings Seeds in Essex outdoors.
This may be due to the long hotter summers we appear to be having, or down to the way we recommend growing this special crop.
Sweet Potatoes have a number of uses in the kitchen. The Sweetest of the flesh can be eaten raw, but is usually eaten boiled, steamed, baked, fried, mashed or even batter fried. The dried roots are also excellent chopped up then mixed with wheat flour and made into interesting bread and cakes. You can even eat the leaves and tips of the young shoots as a substitute for spinach. Making this probably one of the most Versatile Vegetables you could grow.  

Sweet Potato facts

Sweet potatoes are from the Ipomoea batatas family, and belongs to the same family as convolvulus (bindweed) but do not be alarmed, as the plant is non-invasive and is killed off by winter frosts.
Sweet potato roots are forced to form 'slips' (a rooted cutting) and these are what you plant up. These 'slips' we have potted and grown on in our nurseries ready for planting on arrival.

How to Grow

Your Sweet potato Collection will be delivered in May. When you receive your plants provided the weather is not frosty, they can be planted straight away.
It is possible to grow sweet potatoes outside in the warmer parts of the country down South. If growing in the cooler Northern Regions you will need to grow them under cover in Polytunnels or the greenhouse border in Growbags or large pots.

Because Sweet potatoes are related to the annual Ipomoea, they are very vigorous plants. Once they get going they can produce trailing stems up to 3 meters (10ft) long or tall if grown up a framework of canes which can look attractive.     
Sweet Potatoes can be grown in most soil types provided they have had plenty of well-rotted manure or compost added to them in the autumn, and the soil is reasonably free draining.
A few days before planting, the ground should be well cultivated, using a rotovator if possible so the soil is nice and light to produce good tubers in. Then rake in a base fertiliser like Growmore at 60gm (2oz) per square meter.
 Now the soil is prepared, cover the soil with black polythene as this warms up the soil prior to planting. This black polythene is secured and left in place, as the sweet Potato plants will perform better if planted into their final positions through the black polythene. This is done so the soil is kept warm throughout the growing season, which could be a bonus in our unpredictable UK summers.
If the weather turns cold in May prior to planting wait until it is more favourable. If the weather turns cold after planting with biting easterly winds or late ground frosts (which are still possible until June), protect the Sweet Potato plants with some Fleece until the weather improves.
Sweet potatoes are best planted 1meter (3ft) apart between each plant. Simply cut a hole in the polythene at each planting station and plant each Sweet Potato through the plastic. You will find they will soon grow and make a lot of trailing foliage and eventually some decorative small Ipomoea like flowers.
Once planted water in well and keep plants watered during very dry weather. Because of the black polythene there will be no need to weed so growing this crop is easy from now on.
Once the plants are established, you may need to occasionally keep turning the long trailing foliage back onto the polythene area. This will stop them rooting into surrounding soil and wasting valuable energy that is better used in producing those precious tubers.   

Pests and Diseases

Fortunately unlike normal potatoes, Sweet potatoes do not suffer from many Pests. The Only pests they are troubled with occasionally are Aphids. These usually attack the fresh young succulent tips of the foliage as the Sweet potato slips start to grow. Aphids can be controlled using a suitable insecticide or organic soft soap.  
Also during wet weather the foliage may get a slight attack by Slugs or snails, which can easily be controlled, using one of the various Slug controls available.
Luckily Sweet Potato foliage and tubers rarely succumb to any disease problems.  


Sweet potatoes should be ready to harvest approximately sixteen weeks after planting, Which is usually in October or November. If you live in one of the cooler areas, and you are growing in a polytunnel or greenhouse, then you can usually harvest tubers sooner than those grown outside.
Tubers are usually ready to harvest when the stems and leaves have turned yellow, or the early autumn frosts have blackened the foliage, as Sweet potato plants are not hardy.
Once the foliage has changed colour you can cut the stems at the planting hole then clean away the excess foliage. You are now left with a small piece of stem poking through a hole in the black plastic.
The yield per plant will depend on the growing season; in 2017 outside in Essex we averaged 4-5kg of sweet potato tubers per plant.
Now you can see where your tubers are likely to be, so you can carefully remove the black plastic and start to lift the tubers. As the Soil you planted them into was well cultivated this should be quite an easy task using a fork.
Once lifted lay the tubers on some sacking or sheeting for a few days in the Sun to `Cure` the tubers before storing. If a cold or frosty night is forecast move the tubers indoors at night. If the weather is bad after lifting, you can `Cure` them indoors in a warm room at a temperature of 23-29C (75-85F). This method of Curing will harden the skins and extend the storage life of the tubers as well as help sweeten their flavour.
Make sure all tubers that are stored are sound and unblemished to reduce the risk of any fungal storage rots.
Unlike normal potatoes, Sweet potato tubers are best stored in a warm place no cooler than 10-15C (50-60F).  If stored too cold or the tubers become frosted; this will affect the flesh texture and eating quality of tubers.
Stored correctly Sweet potatoes should keep for several months, giving you plenty of time to be a little adventurous, adding this versatile Vegetable to a variety of dishes.


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