We want you to get the best out of your home-grown sweet potatoes. They taste delicious when you harvest them from your own vegetable plot, as the edible tubers imbibe the nutrients and goodness from the soil and grow to a good size on account of the trailing stems, happily flowering in the sun.
For the best start we provide you with slips (the young stems growing from the tubers). They are at just the right size to grow on for yourself and we can supply you with a bunch; every slip can be given a container each for lots and lots of mature potatoes.
1) When they arrive
When they arrive to you, your slips may have wilted; THEY DO REVIVE. We recommend you place them in a vase of flask of water immersing the slips right up to the leaves.
Leave for 24 hours in a cool and dry place- not on a windowsill above a radiator or a sill that receives full sun. An east or west-facing windowsill is perfect.
Arriving in a blister pack, open the blister pack on arrival and check contents. Each plant will already have a well developed root system and a stem and leaves up to 15cm in overall length. If dry lightly mist the root balls to moisten. Prepare to pot on in the next few days, keeping the root ball moist and in a warm light room.
2) Potting on
Once your slips have revived it’s time to put them into pots to grow on under cover until it’s warm enough to grow them outdoors. Fill pots will multi-purpose compost and plant up to leaf height. Keep your pots overnight in temperatures no lower than 13°C (55°F). We recommend a cool porch or unheated room. By day, keep in a light but airy position.
Either plant directly into the heated poly tunnel, greenhouse or 30cm container or nurture in 9cm pot indoors until ready for final planting. Fill a 9cm pot with compost shake soil level with top of pot. Do not firm. With your finger make a hole large enough to take the root ball of the plug plant and push in the plant so that the root ball sits just below the surface. Shake the pot so compost levels, water and keep warm indoors. +15C
3) Choose the site
Sweet Potatoes require full sun and high temperatures and plenty of space to provide good yields. In the UK they are best planted in poly tunnels or greenhouses, however in a warm sheltered outdoor spot they can thrive. In order to increase productivity of the plants try covering the beds in black membrane and ‘planting through’ or planting in black 30cm containers or patio gro bags to increase soil temperature, Fleece and cloches can also help.
4) Prepare the soil
Prepare the soil in prior to planting in late May; make sure it is well drained and aerated. Good drainage is essential so plant in a raised bed if you garden on heavy soil. Not too much nitrogen required.
5) Planting out
Keep an eye out for the roots. By no means do they want to be curling around the side of the pot; curling roots lead to deformed tubers. So you need not repot all the time plant from slips into a large GroSack or 30-40cm (12-16in) diameter pot.
Place outdoors mid-May once temperatures start to rise in earnest, but be sure to bring indoors on a frosty night.
The stems of sweet potatoes trail naturally and provide a natural weed barrier with its ornamental leaves- very useful in the world of home-growing.
Finally enjoy revealing the large mature sweet potatoes about four months later. Note the leaves will have yellowed and start to die back which indicates harvest-time.
5) Harvest and Store
Plants are ready to harvest 120 days after planting, expect to harvest the tubers in October once the leaves turn yellow and die back. The tubers can stay in the ground longer but harvest before the first frosts. Lift in the same way as potatoes and let the skins toughen by leaving them in the sun for a few hours, move to a bright humid place such as a greenhouse for a week or so, to help storage.
5 slips / plants should give at least 5kg -10kg of sweet potatoes depending on location. In the north expect to get 1-2kg of sweet potato tubers per slip, in the warmer south it should be in excess of 2kg per planted slip.
Store sweet potatoes somewhere cool once tubers are completely dry.