Growing potatoes is like reading a good mystery; you have to wait to the very end until what lies beneath the surface is finally revealed. Unlike the end of a book, however, the end of the growing season is sometimes less clear. When’s the right time to dig potatoes?
Potato varieties are divided into groups based on the number of days required from planting date to harvest. Early potatoes, such as Yukon Gold and Red Norland, are ready to dig in 65-80 days. Mid-season potatoes, including popular Kennebec, take 80-90 days, and the late-season varieties mature more than 90 days after planting. Late-harvested potatoes are especially good for longterm storage and, not surprisingly include most russet varieties.
Marking the days-to-maturity date on your calendar at planting time is one way to decide when to dig your early season potatoes. These varieties are great for fresh eating and short-term storage. Starting about a month after my early Reddale plants bloomed, I dug carefully around their roots and stole a few tender young spuds. The creamy, earthy flavor of boiled new potatoes is reason enough to grow my own!
The tried-and-true method for determining when to dig mid and late-season varieties is to wait until the vines turn yellow. After the vines die, I give the spuds another week or two in the ground to let their skins mature. The tougher skins don’t bruise as easily, which is important for a long storage life. I usually grow Carola, a delicious yellow-fleshed variety with yellow skin and a nice oblong shape. With good storage, these will keep until spring.
Cool, dry, overcast days are ideal for digging, and not just for my comfort! To avoid piercing the buried tubers, I push a garden fork into the soil about 18-24” from the center of the plant, angling it under the roots to gently lift the tubers to the surface. Once I’ve revealed a few potatoes, I dig the rest out with my gloved hands. When they were little, my kids loved this ritual and we were a good team: me with the fork and the kids on their hands and knees teasing tubers from the soil and loading them into a cart.
After digging, I brush the soil off, but avoid washing them because it often leads to decay. For the longest storage life, it’s important to let the potatoes mature at 55-60º for a few weeks in a completely dark place. Cull the bruised and damaged tubers for immediate use, then store the rest in a dark, humid place at 40º. Inspect regularly and remove soft and decaying tubers.
For more on growing potatoes, read Harvest Bushels of Potatoes from a Raised Bed.