Potatoes are a rewarding crop for home gardeners across the state, providing a versatile food source that stores well into the winter. Unlike many vegetables, potatoes thrive in cooler soil temperatures, requiring careful timing during the transition from late winter to early spring. This guide offers Kentucky growers specific instructions for preparing their seed, planting correctly, and managing the crop through harvest.
Timing Specific to Kentucky Climate
The ideal window for planting potatoes in Kentucky is between mid-March and early April for the main season crop. The most reliable indicator is soil temperature, which should consistently register between 45°F and 55°F for optimal tuber development and to prevent the seed pieces from rotting.
Potatoes tolerate light frost, allowing planting to occur before the average last frost date. Planting early-season varieties allows for a quick mid-summer harvest, while main-season varieties are intended for storage.
Western Kentucky, which is warmer, can often begin planting in mid-March, with a possible window extending into early July for a late crop. Eastern Kentucky, with its cooler, higher-elevation areas, typically begins planting later, generally in late March, with successful plantings concluding around early June.
Preparing the Seed and Soil
The process begins with selecting certified disease-free seed potatoes. Larger tubers must be cut into pieces roughly 1.5 to 2 ounces, ensuring each piece contains at least one or two eyes. After cutting, leave the pieces in a single layer in a well-ventilated area for two to three days. This allows the cut surface to dry and form a protective, cork-like layer, preventing the seed piece from rotting once planted.
Many growers also “chitt” their seed potatoes by placing them in a bright, cool location (around 50°F) for several weeks before planting. This exposure encourages the development of short, sturdy sprouts, giving the plant a head start.
Potatoes grow best in loose, well-draining soil amended with organic matter to prevent compaction. Avoid applying excessive nitrogen fertilizer at planting. Too much nitrogen promotes extensive vine growth above ground at the expense of tuber formation, potentially reducing the final yield.
The Physical Planting Process
To plant, dig a trench 4 to 6 inches deep in the prepared soil. Place the seed pieces, eyes facing upward, 12 to 15 inches apart within the row. Rows should be spaced about 3 feet apart to allow room for hilling. Cover the seed pieces with only 2 to 3 inches of soil initially.
This shallow covering allows the soil to warm, encouraging faster emergence. Once the potato plants emerge and reach a height of 6 to 8 inches, the first hilling must occur. Hilling involves drawing loose soil up and around the base of the stems until only the top few inches of foliage remain exposed. This action is necessary because tubers develop on underground stems called stolons, and mounding the soil provides more space for them to form.
Post-Planting Care and Harvest
Continued care focuses on moisture management and repeated hilling throughout the growing season. Repeat the hilling process every time the foliage reaches another 6 to 8 inches in height. This keeps developing tubers completely covered, preventing sunlight exposure that causes them to turn green and become inedible.
Consistent watering is necessary, especially once the plants begin to flower, signaling the start of tuber development. Plants require about one inch of water per week during this phase; moisture stress can lead to malformed potatoes. Reduce watering once the foliage begins to yellow to allow the soil to dry slightly and the potato skins to thicken before harvest.
There are two distinct harvest timings. New potatoes are small and thin-skinned, harvested shortly after the plants flower. For storage potatoes, wait for the foliage to completely die back naturally (typically 90 to 140 days after planting), then wait an additional two weeks for the skins to set firmly.
When harvesting, carefully dig up the area outside of the hilled mound using a digging fork to avoid bruising the tubers. Potatoes intended for long-term storage require a curing period immediately after harvest. This involves placing the unwashed potatoes in a dark, well-ventilated location (45°F to 60°F with 85 to 95% humidity) for one to two weeks. Curing heals minor wounds and thickens the skin, preparing the potatoes for storage near 40°F.