Potatoes are a rewarding crop for Colorado gardeners. While the state’s varied climate presents a challenge, successful planting depends entirely on timing. The potato plant is a cool-season vegetable that thrives in the spring before the intense heat of summer. Correct timing ensures the tubers develop fully before the season becomes too hot or too dry. This precise timing requires attention to regional weather patterns and soil conditions rather than a fixed date.
Determining the Right Planting Window
The optimal moment to plant potatoes in Colorado is generally two to four weeks before the average last frost date in your specific area. This early planting allows the tubers to establish themselves in the cool spring soil. Potatoes can tolerate a light frost, but heavy freezes can damage emerging foliage, so monitoring local forecasts is important.
Colorado’s diverse geography means the planting window varies significantly across the state’s major regions. Gardeners in the lower-elevation Front Range and Eastern Plains typically plant earliest, around mid-March to mid-April, when the soil becomes workable. The Western Slope often follows, with planting dates falling into late April. High mountain valleys and areas above 7,000 feet have the shortest growing seasons, pushing planting back to late May or early June, after the danger of hard freezing is mostly past. The minimum soil temperature for planting is 40°F, but potatoes will sprout and grow faster once the soil consistently reaches 45°F to 50°F.
Preparing Seed Potatoes and Soil Conditions
Before planting, prepare certified seed potatoes, which are specially grown to be disease-free. A beneficial pre-planting technique is “chitting,” which encourages the seed potatoes to sprout before they are placed in the ground. To chit, place the potatoes in a bright, cool, and frost-free area, such as an unheated porch or garage, until short, sturdy, purple-green sprouts form from the “eyes.”
Larger seed potatoes should be cut into pieces roughly the size of a medium hen’s egg. Each piece must retain at least two healthy “eyes.” These cut pieces must then be allowed to cure for one to two days in a cool area to form a protective calloused layer over the cut surface. This drying process prevents the seed pieces from rotting once they are planted in cool, moist soil. The planting site needs loose, well-drained soil, ideally a sandy loam, which prevents developing tubers from becoming misshapen or rotting.
Essential Planting Techniques and Ongoing Care
Potatoes should be planted in a shallow trench or hole approximately 4 to 6 inches deep, with the cut side facing down and the chitted sprouts pointing up. Space each seed piece about 10 to 12 inches apart within the row to give the plants adequate room. Immediately after planting, cover the seed pieces with only a few inches of loose soil, leaving the trench partially unfilled.
The most important maintenance task during the growing season is “hilling,” which involves mounding soil or organic material around the stems as the plants grow taller. This process should begin when the plants reach about 6 to 8 inches in height and be repeated every few weeks. Hilling serves two purposes: it encourages the plant to produce more tubers higher up the stem, and it shields developing tubers from sunlight exposure. Tubers exposed to sunlight will turn green due to the production of solanine, a toxic compound.
Consistent moisture is required for healthy tuber development, especially once the plants begin to flower, which signals the start of the tuber-forming period. While the soil must be kept evenly moist, avoid overwatering or creating soggy conditions, which can lead to rot and disease. Once the foliage is fully grown, adding a layer of organic mulch, like straw, helps keep the soil temperature cool and consistent, favoring higher yields.
Harvesting and Curing
Harvest time depends on the desired use, distinguishing between “new” potatoes and full-sized storage potatoes. New potatoes are small, thin-skinned, and best for immediate consumption; they can be dug up shortly after the plants begin to flower. For the main harvest of storage potatoes, wait until the plant’s foliage naturally begins to yellow and die back, typically 90 to 120 days after planting.
Once the foliage has fully died back, stop watering and wait about two weeks before harvesting. This waiting period allows the potato skins to thicken and “set.” Dig carefully with a fork or spade, starting several inches away from the plant’s center to avoid piercing the tubers. After lifting the potatoes, brush off the dirt without washing them, as moisture can encourage rot in storage.
The final step for long-term storage is curing, which hardens the skin and allows minor wounds to heal. Curing involves keeping the potatoes in a dark, well-ventilated space with high humidity and a moderate temperature, ideally between 45°F and 60°F, for one to two weeks. Once cured, they can be stored in a dark, cool location, around 40°F to 45°F, for several months.