The potato is a staple crop cultivated globally and is botanically a tuber, a thickened part of the plant’s underground stem used to store energy. Determining how long it takes to grow potatoes is highly variable. The duration depends significantly on the specific variety planted, environmental conditions, and preparation steps taken before the seed potato touches the soil. Understanding the different phases, from pre-planting preparation to maturity, is necessary to gauge the timeline for a successful harvest.
The Typical Growth Cycle Timeline
The time from planting a seed potato to harvest generally falls within a broad window of 70 to 130 days. This wide range exists because potato varieties are categorized based on their maturation period.
Early varieties, sometimes called “new potatoes,” are the fastest to reach an edible size, typically requiring 60 to 90 days. These tubers are smaller and have thinner skin, making them suited for immediate consumption rather than long-term storage.
Mid-season varieties take 80 to 110 days to mature. These offer a good balance between early harvest and a substantial yield.
Late-season varieties, also known as maincrop potatoes, require 100 to 130 days to reach peak maturity. Maincrop potatoes are the largest, develop thicker skins, and are the best choice for storing over the winter months.
Pre-Planting Preparation Time
An optional but beneficial preparation phase, known as “chitting,” often precedes planting. This process involves encouraging the seed tubers to sprout before they are set into the soil. Chitting is accomplished by placing the seed potatoes in a single layer in a cool, light, and frost-free area, such as a windowsill.
This exposure stimulates the development of short, sturdy sprouts, known as chits, from the “eyes” of the potato. The process typically takes between four and six weeks before the sprouts are ready for planting. By giving the potatoes this head start, gardeners can shave one to two weeks off the total growing time, which is advantageous in regions with shorter growing seasons.
Factors That Influence the Harvest Date
The timelines associated with each variety are estimates and can be altered by environmental factors throughout the growing season. Soil temperature plays a major role in tuber development, with the ideal range for formation and bulking being between 60°F and 70°F. If the soil remains too cold, or if temperatures consistently climb above 86°F, the plant’s growth can slow down or halt completely.
Consistent water availability is paramount, especially during the tuber bulking phase when potatoes rapidly increase in size. Fluctuations in soil moisture, such as drought followed by heavy watering, can lead to physiological defects like growth cracks or malformed tubers.
The amount of sunlight and the length of the day also influence the total growth period; longer day lengths can delay the initiation of new tubers. Additionally, excessive nitrogen fertilizer promotes vigorous leaf growth but can delay the overall maturity of the tubers beneath the surface.
Knowing Exactly When to Harvest
The most reliable indicator that potatoes are ready to be harvested is the visual sign of the plant’s foliage, or haulms, beginning to yellow and die back. For maincrop varieties intended for storage, harvest should be timed when the majority of the foliage has withered. This indicates the plant has diverted all its energy into the underground tubers. Waiting until the foliage has fully died back ensures the potatoes have developed a mature, thick skin that will resist damage and store well.
Before harvesting for storage, stop watering the plants one to two weeks prior to the intended digging date. This period of reduced moisture helps the skin of the tubers to properly “set” or toughen up.
Once dug, the potatoes benefit from a curing process. They are kept in a dark, humid, and cool environment for ten to fourteen days to heal minor scrapes and fully harden the skin for long-term storage.