Growing potatoes in bags offers a practical method for gardeners with limited space, providing an excellent alternative to traditional in-ground cultivation. This container method maximizes small areas like patios or balconies and gives the grower complete control over the soil composition. Furthermore, potato bags simplify the harvest process, eliminating the need for extensive digging by allowing the gardener to simply tip out the contents. Success relies on specific preparation steps and understanding the unique growth habit of the potato plant.
Preparing Your Seed Potatoes and Materials
Selecting the right container is the first step. Fabric grow bags are a popular choice because their porous nature ensures superior drainage and air circulation. A container size of at least 10 to 15 gallons is recommended for a healthy yield, though plan for a minimum of five gallons of soil volume per plant.
The growing medium requires a light, airy, and well-draining mixture. Standard garden soil is unsuitable as it compacts easily in containers and can harbor disease. An ideal mix consists of approximately equal parts soilless potting mix and quality compost, which provides essential nutrients and helps retain moisture.
Before planting, seed potatoes benefit from “chitting,” which encourages the development of strong, short sprouts indoors. Place the seed potatoes in a cool, bright, frost-free location, such as an egg carton, with the end containing the most “eyes” facing upward. After about four to six weeks, once the sprouts reach approximately one inch in length, the seed potatoes are ready for the bag. If the seed potatoes are large, cut them into smaller pieces, ensuring that each section retains at least two eyes. Allow the cut surfaces to dry for a day or two before planting to prevent rot.
Initial Planting and Creating the Base Layer
The initial setup requires only a partial filling of the bag. Begin by adding four to six inches of the prepared potting and compost mixture to the bottom, serving as the base layer for root establishment.
Place the chitted seed potatoes directly onto this base, sprouts pointing upward. Position them about five to six inches apart to prevent overcrowding. Cover the seed potatoes with an additional three to four inches of the growing medium and water gently to settle the soil.
Managing Vertical Growth Through Hilling
The technique of “hilling” is the primary method used to maximize yield in a bag system. It involves progressively adding more soil or compost around the developing stems as they grow taller. This action encourages the plant to form new tubers, which develop from underground lateral shoots called stolons.
Potatoes form new tubers along these buried stems. By covering the stem, the plant is induced to produce more tuber-bearing structures along the newly buried portion, creating multiple layers of potential harvest. Begin hilling once the green foliage reaches six to eight inches above the existing soil line.
Add four to six inches of the growing medium around the stems, leaving only the top third (approximately four inches) of the leafy growth exposed. Repeat this process every time the plant grows another six to eight inches, continuing until the bag is filled to the top rim. Once the bag is full, the plant will focus its energy on maturing the tubers.
Watering, Feeding, and Harvesting
Container-grown potatoes require diligent moisture management because the bag material allows for faster evaporation. Maintain consistently moist soil that is never soggy, which can lead to tuber rot. Check the moisture level by inserting a finger one to two inches deep, watering thoroughly until excess drains from the bottom when the surface feels dry.
Potatoes are heavy feeders and benefit from a balanced fertilization schedule. After the shoots emerge, apply a balanced soluble fertilizer every couple of weeks throughout the growing season. Use a formulation higher in phosphorus and potassium (e.g., a 5-10-10 ratio), as too much nitrogen encourages leafy growth at the expense of tuber production.
Harvesting is signaled by the natural dieback of the foliage. When the leaves turn yellow and begin to wither, the tubers have reached maturity. To prepare for storage, stop watering the bag entirely about two weeks after the foliage yellows, which helps the skins toughen.
Harvesting is accomplished by tipping the entire bag onto a tarp to collect the mature tubers. Do not wash the potatoes immediately, as this encourages spoilage. Gently brush off excess soil and allow the harvest to cure in a dark, warm, and humid environment (ideally 45 to 60 degrees Fahrenheit) for one to two weeks. This curing period allows minor scrapes to heal and the skin to fully thicken for extended storage.