How Do I Grow My Own Sweet Potato Slips from a Tuber?

Rather than buying new slips every year, you can produce your own sweet potato slips by sprouting saved tubers from your previous harvest. A single medium-sized sweet potato can produce ten to twenty slips, making home propagation extremely economical. The process takes six to eight weeks and requires only warmth, light and a jar of water or moist compost — but timing matters enormously for short-season climates.

Selecting tubers for propagation

Choose firm, healthy tubers with no signs of disease or damage for propagation stock. Store these separately from tubers you intend to eat. Do not propagate from tubers harvested from plants that showed virus symptoms (mottled or distorted leaves) — virus is carried internally in the tuber and all slips from it will be infected. Ideally use tubers from the most vigorous, productive plants in your bed as your propagation stock — you are selecting for plant quality over generations.

Starting the sprouting process

Begin sprouting in late February to March for planting out in late May to June (depending on your climate). Place tubers in a warm (20–25°C), bright spot to initiate sprouting. You can half-submerge the tuber in a jar of water (held up by toothpicks) so that the lower half is in water and the upper half is in air — this is the classic kitchen method. Alternatively, bed the tubers in moist compost or vermiculite in a warm propagator. Shoots emerge from the tuber within two to four weeks in warm conditions.

Taking slips from the sprouting tuber

When shoots are 10–15 cm long and have several leaf nodes, remove them from the tuber. Twist or cut them from the tuber surface, leaving the base attachment point on the tuber so more shoots can continue to develop from it. A single tuber may produce ten to twenty successive slips over four to six weeks if kept warm. Immediately root the slips in water or moist compost — do not allow them to dry out after cutting.

Rooting and hardening off

Root slips at 20°C+ in water or moist compost for seven to fourteen days until the roots are 2–5 cm long. Harden off gradually over one to two weeks by moving them to progressively cooler and more exposed conditions before planting out. Do not plant out until soil temperature is at least 18°C and all frost risk has passed.