Sweet potato
Grow
Ipomoea batatas.
Like potatoes, sweet potato are a ‘dime a dozen’ when in season so I only grow them for the fun of trying as our garden isn’t huge. However, if you have a taste and the space for them then they are well worth including in your spring planting schedule. Like their starchy cousins, sweet potato can be grown as a ground cover plant and soil conditioner with their dense foliage suppressing weeds and the action of their roots improving soil structure.
In a nutshell
- Warm sunny spot
- Shallow rich soil
- Plant tubers or cuttings
- Can grow in pots
- Fun for kids
Quantity
2 plants per person
Companions
- Sunflower
- Cosmos
The growing lifecycle
Kumara
Kumara
Kumara
Kumara
Kumara
Kumara Harvest
Kumara Harvest
Kumara
Top 2 varieties
1. Beauregard
Produces medium sized, orange coloured tubers that are high in Beta-carotene.
2. Bonita
Produces white-fleshed tubers that are extraordinarily sweet.
Getting started
When
There are several sweet potato varieties that grow well in the UK, generally in the more mild South West. Varieties can be planted indoors into small pots from late April onwards. Alternatively plant them inside greenhouses. Less resistant varieties need to be kept inside greenhouses permanently, however there are tougher cultivars that can be transplanted outside once the frosts have passed.
Where
A warm and sheltered sunny part of your garden.
Soil
Sweet potato are grown in free draining, rich organic material above a hard soil base which stops their roots running and running and tells them its time to develop the edible tubers. This is one vegetable where deep and thorough digging is therefore to be discouraged. The best way to grow them in an open garden is to mound up soil, sand, rotted manure and compost into a shallow hill that is as wide and as long as the area you want to plant in. This hill should be about one and a half hands deep. As well as rotted manure and compost you can add wood ash and seaweed for extra potassium.
Sweet potatoes can also be grown in anything from a stack of old tyres or a half wine barrel to a plastic bin bag (see end of text).
Sow & plant
Sow & Plant
Sweet potatoes are planted as green shoots – or cuttings – and as sprouted tubers with shoots coming out of them. Cuttings can be purchased from garden centres, nurseries and some health food stores in spring. If you plan to grow outdoors, make sure to buy cuttings from more resistant cultivars (such as the aforementioned ‘Beauregard’).
Growing outdoors:
Plant cuttings into pots. Once they are around 10in tall, harden off your cuttings over a week or more before planting outside. This involves taking them out into the sunlight in daytime and recalling them at night until they are ready for a permanent residence outdoors.
Nestle your cuttings about an arm’s length apart on your hill of prepared soil. Cuttings should be buried about a finger deep and planted with their bottom half in the soil. They need good access to moisture for the first week or two, so if its dry water accordingly. Remember that sweet potatoes like warmth, so don’t plant them outside until all risk of frost has passed. Thereafter they should be able to fare for themselves.
Growing indoors:
Less resistant cultivars grow well in poly-tunnels. You can use supermarket bought sweet potatoes (which are more than likely from warmer climates) to create sprouted tubers. This involves burying a few tubers in boxes of moist sand and placing them in a warm sunny position indoors. Once these boxed individuals have produced shoots that are about half a thumb’s length they can be planted into the poly-tunnel. Alternatively you can let the shoots grow to a hand’s length and then remove them from the tuber before planting these multiple specimens into you greenhouse.
Place the cuttings an arm length apart and plant them with their bottom half in the mound of soil you have prepared. Tubers need the same spacing and are buried about a finger – length deep. Cuttings and tubers need good access to moisture for the first week or two, so if its dry water accordingly. Thereafter they should be able to fare for themselves.
Maintain
When shoots start to form runners and cover ground they should be periodically lifted to stop them from taking root on the surface.
Containers: If you are planting in containers this can make it easier to utilize the sunnier parts of your garden and to contain the sprawl of these plants in smaller gardens.
Planting into car tyres, half wine barrels or plastic bin liners is relatively easy and can be fun for kids:
Mix up soil, sand and rotted manure, compost and seaweed in a wheelbarrow.
Position your half barrel and ensure it has several drainage holes in the bottom. If using tyres, place two or three on top of each other. If using a large bin bag, open one up and place on the ground. Make about 10 or 12 small holes for drainage in the bottom of the bag.
Fill your chosen planting container with prepared planting mix.
Plant 2 to 3 sprouted tubers per bag, barrel or tyre stack. Tubers should be buried about a finger deep.
Water as needed in first two weeks and then sparingly thereafter – only when it is dry.
Harvest or pick
Sweet potato need between 4 and 5 months to mature. Wait until foliage has all turned yellow before digging carefully. I do this by hand in containers. Once lifted, they are left on the soil’s surface to cure (develop are dry, firm skin) for a few days. Store undamaged tubers in sacks in a cool dry, frost-free place.
