No matter how hard I try, little potatoes get past me on harvesting day, and then spring to life as volunteers among cabbage or corn the following year. The volunteer potatoes are robust plants, because they are growing the way potatoes want to grow, as perennials. Native to the Andean Mountains in South America, potatoes are very much perennials that die back in winter and regrow from fat storage roots (potato tubers) when the weather warms in spring.
Can You Plant Potatoes in the Fall?
You can mimic nature’s natural plan for potatoes by planting potatoes in the fall. Not all of them – your big planting can wait until spring. But fall is the time to plant the little potatoes that have turned green in storage, or the ones you found one day while digging in the garden and left outside in a dirty pail. Gardening experts in Wisconsin recommend fall potato planting so the plants can establish themselves ahead of cutworms and weeds in spring. I like having a good use for my puniest potatoes.
You can expect success planting potatoes in the fall as long as your soil gets cold and stays cold in winter, with temperatures 8 inches (20 cm) below the surface staying below 48°F (9°C). Buried potato tubers start growing as soil temperatures rise above 50°F (10°C). Your garden gets a vote, too. If you often see volunteer potatoes in your garden, planting potatoes in the fall should work out well.
Please note: If you live in a mild winter climate where the soil does not chill down, it is best to wait until late winter to plant potatoes. The plants can then enjoy uninterrupted growth in mild spring weather and make a crop before the weather gets hot.
Seed Potatoes for Fall Planting
You won’t find seed potatoes at nurseries this time of year, so you will need to come up with your own. If you don’t have some little sprouters left from your summer harvest, you can prep and plant small potatoes from the market. Before planting, let the potatoes sit in a warm, well-lit place to green up for a few days. Green skins on potatoes are evidence that the tuber has equipped itself with bitter solanine compounds that make it unpalatable to critters.
Whether they are large or small, keep potatoes whole when planting potatoes in the fall. Cut potatoes are much more likely to rot or get eaten by voles compared to whole potatoes. Spring-planted potatoes grow so fast that cutting does little harm, but potatoes planted in cold soil should be left whole to give them the best chance at survival.
Mulching Fall Potatoes
There are plenty of leaves around in the autumn, and they make a great mulch for potatoes planted in the fall. A leaf mulch cushions the soil from compaction caused by heavy rain, and keeps the soil cool through periods of mild winter weather. Some gardeners put leaves directly into the planting trenches when planting potatoes in the fall, but this is merely an option. The important thing is to have the surface well covered to prevent weeds and erosion, but not mulched so deeply that the potatoes think winter is over.
Some gardeners report earlier emergence of fall planted potatoes, but mine tend to be a bit late, perhaps because I plant them quite deep, about 10 inches (25 cm) below the surface. Here I am copying the potato’s ploy, because most of the volunteer potatoes in my garden grow from tubers buried beyond the reach of my hand spade, appearing after the space has been cultivated and planted with something else.
Why not just let the volunteer potatoes grow? Leaving potatoes to grow in place sets the stage for soil-borne diseases to develop, and here we are talking about potato problems like nematodes and scab and pink rot that never manifest when soil is given restorative breaks between potato crops. Potatoes that are intentionally planted in fall get a fresh location and time to settle in, a win-win strategy for a nice little crop of summer potatoes.