Growing Guide for Sweet Potatoes
If you can’t start sprouting your seed immediately, tubers can be stored at above 55° for several weeks. Definitely start sprouting by mid April. To germinate sweet potatoes, spread 3" of potting soil in a crate or other well-drained container, arrange the tubers on top so they aren’t touching, and add enough soil to cover by a few inches.
Keep the soil in your bedded-down crate at 75-80° with a heat mat or heated greenhouse. Keep in direct sunlight and water daily. Don’t allow soil to dry out, but don’t let it get waterlogged. Maintain these conditions for about 6 weeks and watch slips (sweet potato sprouts) shoot out of the bedding.
Taking Cuttings and Rooting
Once slips are 6-12", dig out each seed piece from the crate. At each eye, slice off the clump of shoots and pull apart so that you’re left with individual plants, each with roots, stem and leaf. It’s not crucial that each slip is perfect, as only a bit of plant material is needed for it to root. If it’s still too cold outside to transplant, pot up the slips, or root them in warm water in your greenhouse for up to several weeks. Adding fish hydrolysate with kelp to the water can be a huge help during this stage.
Gently harden off your slips as you would tomatoes after the last frost. Plant on a warm overcast June day when soil temps have warmed to at least 60°. Set slips out in mounds, either in a hoophouse, with black plastic, or under hooped row cover (any combination of these techniques is fine). Sweet potatoes like a loose soil bed with plenty of organic matter and micro-nutrients—think Kelp Meal and Azomite. Spacing is crucial. Plant 18" apart, one row per bed. Water in well to prevent serious transplant shock.
Harvest and Curing
Harvest just before frost. Before storing, spread in a single layer in a greenhouse or room above 70° for 10-14 days. After curing, store above 55°, and enjoy!