The Daily Telegraph - Saturday
How to propagate your own sweet potato ‘slips’
Cut a large section of sweet potato.
Use cocktail sticks to suspend the root section in the neck of a glass vessel just touching the water.
Wait for the tuber to shoot from the top, with roots forming on the sides.
When there’s a decent clump of root, cut the potato into sections, each with a bit of root.
Pot each into soil and keep moist, particularly to begin with when the roots are making the transition from water to soil.
At West Dean, they found that if roots did not appear, potting them up into compost (halfburied) seemed to encourage reluctant rooting.