When Do You Plant Potatoes?
From planting to digging, depending on variety and weather, Irish potatoes take about three or four months to mature, with some early varieties and immature or “new” potatoes harvested a little earlier.
How to Grow Potatoes 05:02
Irish potatoes require cool weather – neither freezing nor broiling hot – to survive and produce edible underground tubers. Depending on variety and weather, the potato growing season is about three or four months or so from planting to digging, with some early varieties and immature or “new” potatoes harvested a little earlier.
How It Happens
Potatoes are planted from small pieces of mature tubers, called “seed” potatoes, each with one or two buds. In addition to cool weather, they require at least 7 or 8 hours of direct sunshine, very well-drained soil, and moderate fertilizer.
Most gardeners cut seed pieces two or three days ahead of time to allow cut surfaces to heal which reduces rotting when they are planted in cold, wet soils. The pieces may also be allowed to sprout before planting, which is especially important in areas where the growing season is cold and short.
Plant as soon as soil can be dug in early spring; if the weather then is typically rainy, plan ahead by working up rows or hills in the fall. In freeze-free areas of the country, including the Southwest and along the Gulf Coast, potatoes can be planted in the fall or winter; however, it is usually difficult to find seed potatoes then, so they must be ordered and stored ahead of time.
Once the seed pieces are planted, usually two or three inches deep and a foot or so apart in rows or in hills or even containers, they sprout quickly into lush, leafy, multiple-stem plants. As the plants grow, new tubers begin to form on short stolons that grow downward into the ground. Because potatoes exposed to sunlight turn green, which causes them to taste bitter, it is important to pile soil or heavy layers of straw or other mulch around lower stems so the tubers are grown in complete darkness. This is often done every week or two until the plants have at least six inches of lower stem buried.
Weather is Crucial
While healthy potato plants can tolerate light frosts, and may even recover from mild freeze damage, they cannot survive hard freezes. This is why potatoes must be planted in cool weather – after the danger of freezing is past, but well before hot weather sets in for the summer.
Heaviest tuber formation occurs when soil temperatures are in the 60-70 F range, and stops when soil temperatures reach 80 degrees or so. Mulching soil with straw or other organic matter can help reduce soil temperature by as much as 10 degrees.
So you must time your planting between hard freezes and hot temperatures. Depending on local weather, most gardeners plant in March, April, or May, and expect a harvest about four months later, starting to dig new potatoes about two to three weeks after plants flower. But again some can be planted in the fall in mild-winter areas.