Growing potatoes in a box or container is a practical solution for gardeners with limited space, especially in urban environments. This method simplifies cultivation by eliminating the need for extensive trenches and making the final harvest significantly easier. The container gives the gardener greater control over soil quality and growing conditions. This straightforward technique focuses on vertical growth to maximize tuber production.
Container and Soil Preparation
The foundation for a successful container potato crop starts with selecting the appropriate box and specialized growing medium. An ideal container should be opaque to block light, approximately 15 to 20 gallons in volume, and at least 18 inches deep for adequate layering. The container must have numerous drainage holes at the bottom to prevent waterlogging, which can cause tubers to rot.
Heavy garden soil is unsuitable for containers because it compacts easily, drains poorly, and may introduce diseases. A loose, well-draining mix is preferred, often composed of a blend of soilless potting mix, aged compost, and potentially some peat moss. This blend provides necessary aeration and moisture retention while supplying nutrients.
Initial Planting of Seed Potatoes
Certified seed potatoes must be prepared before planting to ensure vigorous growth. This preparation involves “chitting,” where potatoes are placed in a cool, bright, frost-free location for several weeks to encourage short, sturdy sprouts, or “eyes.” If a seed potato is larger than a golf ball, cut it into pieces, ensuring each piece contains at least one or two healthy eyes.
After cutting, allow the pieces to air-dry for a day or two until the cut surface forms a protective callus, which helps prevent rot and disease. To begin planting, fill the container with approximately 4 to 6 inches of the specialized soil mix. The seed potato pieces are then placed onto this layer with the sprouts facing upward, spaced about 10 to 12 inches apart, and covered with another 2 to 4 inches of soil.
Layering Soil and Ongoing Maintenance
The core technique of growing potatoes in a box is layering, commonly known as “hilling,” which encourages the plant to produce more tubers along the buried stem. This process begins once the young potato plant’s foliage reaches 6 to 8 inches above the soil line. Gently add more soil, compost, or straw around the stem, covering the lower leaves and leaving only the top few inches of foliage exposed.
Repeat this layering every time the plant grows another 6 to 8 inches until the container is filled. The purpose of hilling is twofold: it provides a deep, loose medium for new potato tubers to form along the buried stem, and it prevents developing potatoes from being exposed to sunlight. Exposure to sunlight causes tubers to turn green and produce solanine, a toxic compound that makes them inedible.
Consistent watering is necessary because potted soil dries out faster than garden beds. Keep the soil evenly moist but never soggy, checking frequently, especially in hot weather. Adequate moisture is crucial during the tuber formation stage for a good harvest. Potatoes also require a minimum of six to eight hours of direct sunlight daily for healthy growth.
Knowing When and How to Harvest
The visual signal that the potato crop is nearing maturity is the dramatic change in the plant’s foliage. For main-crop varieties, the plants will begin to yellow and eventually die back completely, indicating the end of the growth cycle. This dying back shows that the plant has finished directing energy to the leaves and has fully matured the underground tubers.
Once the foliage has completely died down, wait approximately two weeks before harvesting. This waiting period allows the potato skins to thicken or “set,” which improves their ability to be stored long-term. The box method makes harvesting easy; simply tip the container onto a tarp and sift through the loose soil to collect the potatoes. Freshly harvested potatoes should be cured in a cool, dark, and well-ventilated location for a few days to harden the skin before storage.