St. Patrick’s Day is just around the corner, so we know it is time to get our seed potatoes in the ground. Actually any time from mid- to late-March is fine for potato planting.
Be sure to buy seed potatoes rather than using those bought for cooking. Seed potatoes are certified disease-free and have plenty of starch to sprout as quickly as soil temperatures allow. Most seed potatoes can be cut into four pieces, though large potatoes may yield more.
Each seed piece should be between 1.5 and 2 ounces to ensure there is enough energy for germination. Each pound of potatoes should yield eight to 10 seed pieces.
Cut the seed two to three days before planting so freshly cut surfaces have a chance to suberize, or toughen, and form a protective coating. Storing seeds in a warm location during this suberization will speed the process.
Plant each seed piece about 1 to 2 inches deep and 8 to 12 inches apart in rows. Though it is important to plant potatoes in March, emergence is slow. We are often into late April before new plants poke their way through the soil.
As the potatoes grow, pull soil up to the base of the plants. New potatoes are borne above the planted seed piece, and we don’t want sunlight hitting the new potatoes. Exposed potatoes will turn green and produce a foul, bitter-tasting poisonous substance called solanine. (The amount of solanine to make one sick is like 60 large potatoes in a single meal.) Keeping the potatoes covered will prevent this.
Harvest the potatoes when the vines are about half dead. Remove the excess vines and carefully dig the tubers. Allow them to surface dry, out of the sun, for a day or more to prevent sun scalding and then store in a cold, dark location (below 40 degrees is ideal).
Small-space gardeners need not lose hope. A method using a rather large pot and potting mix works quite well. Place three to four suberized pieces in a 2-inch base layer of potting mix. Cover this base layer with another inch or two of potting mix. When growth is 2 to 3 inches above the second soil layer cover again with 2 inches of mix (yes, leaves and all).
Continue covering the new growth until the pot is full, and then allow the potatoes to mature. At harvest, push the pot over and simply sort the mix, no digging required.