Potatoes are one of those vegetables that seem so plain and cheap…so why allot precious garden space to growing them? Not only are there many more different varieties of potatoes that what we see in the grocery store, but potatoes are also incredibly satisfying because they are so easy to grow! Potatoes have few pests and diseases to contend with in our area, and for the most part don’t require constant tending. While fertile soil and regular watering well help produce a larger harvest, we’ve even seen totally neglected potato plants that have never been hilled (but were originally planted with a thick layer of mulch) produce an admirable crop, making them a great value in the garden.
We can get two potato harvests in our Chicagoland climate – one in July and another in October. For a July harvest, plant seed potatoes (cuttings or whole potatoes containing at least one “eye”, not actual seeds) in mid-April. You can start the potatoes a little earlier by putting the seed potato or cutting in a 2-4″ pot with potting soil a few weeks before transplanting, which will result in a small plant that looks like a tomato seedling. This can be transplanted outdoors in the same way as a tomato – with the stem buried in the ground. For an October harvest, plant by mid-July. Potatoes will grow well in the soil, in a container, or in a raised bed.
Though typically called “root” vegetables, potato tubers form from modified stems called stolons.
Why hill potatoes? Hilling is simply covering the potato vines with loose soil, usually twice during the growing period. This is done for two reasons: 1) to provide more soil contact with stems, which will put down more stolons to produce potato tubers, resulting in a larger harvest and 2) to cover potato tubers that have formed close to the surface with soil, preventing light exposure, which can result in increased levels of solanine, a toxic substance.
While there’s a lot of worrying done by new gardeners on when to hill potatoes, or how much, as long as you have an adequate layer of mulch on your soil at planting time, you can get away with not hilling at all. Hilling is typically done when the plants are about 1′ tall (adding about 8-10″ of loose soil around the stems), and again adding about 4″ a few weeks later.
Some potato varieties will produce blossoms, which usually correlate to the color of the potato tuber. You may even notice that these flowers form fruits that look similar to tomatoes, after pollination. These fruits will have seeds inside that can be planted to grow more potatoes, though they will take longer to grow than those started from “seed potatoes”.
Potatoes are ready to dig after the vines have started to die back. The best way to harvest potatoes from a raised bed or a container is with gloved hands. Sticking a digging fork or shovel into the soil often results in wounded potatoes, that should be washed and eaten right away.
Storing potatoes: If you aren’t planning to eat your potatoes soon after harvesting, you can “cure” them which helps develop thicker skins for storage. After harvesting, place unwashed (but with big chunks of soil removed) potatoes in a shallow cardboard box. Cover loosely with black and white newspaper or burlap and keep at room temperature for several days. After this time, the potatoes will have a thicker skin, allowing them to be washed without removing the tender skin typically found on just-dug potatoes. After washing, dry thoroughly and keep in a cool, dark place. If you have a large amount of potatoes to store, check out these tips from University of Idaho Extension.