A potato grow bag is a flexible, heavy-duty container, often made of breathable fabric, used to cultivate potatoes. This method bypasses the need for a traditional garden plot, allowing gardeners to utilize patios, balconies, or small yards for a substantial harvest. Grow bags offer space efficiency, simplified, damage-free retrieval of the crop, and complete control over the growing medium, which is a significant factor in tuber development.
Setting Up the Grow Bag
Selecting the appropriate size bag is the first step toward a successful yield, with a 10-gallon capacity generally recommended as a minimum for a manageable harvest. A 10 to 15-gallon container provides sufficient depth and volume for the tubers to develop fully. Position the bag in a location that receives a minimum of six hours of direct sunlight daily, as potatoes require full sun exposure to thrive. The chosen site must also offer good drainage, which fabric bags naturally facilitate.
Before planting, prepare your certified seed potatoes. Place them in a bright location with indirect light for two to three weeks to encourage short, robust sprouts, a process known as chitting. If any seed potato is larger than a golf ball, cut it into pieces, ensuring each piece contains at least one or two “eyes,” which are the growth points. Allow the cut surfaces to cure and dry for a day or two before planting to minimize the risk of rot.
The initial growing medium should be a light, well-draining mix. Avoid using heavy garden soil, which can compact easily and impede tuber expansion. Fill the bottom of the grow bag with this mix to a depth of approximately four to six inches.
Planting and Hilling Techniques
With the base layer established, place three to four prepared seed potato pieces directly on the soil surface in a 10-gallon bag, spacing them evenly. Position the pieces with the most eyes facing upward toward the light, as these growth points will become the main stems. Gently cover the potatoes with an additional two to three inches of the prepared soil mixture, taking care not to damage any emerging sprouts. Water this initial layer thoroughly to settle the soil and initiate growth.
The unique aspect of growing potatoes in bags is the method of “hilling.” Hilling is necessary because potatoes form on underground stems called stolons, and burying the main stem forces the formation of more stolons. Begin the first hilling when the newly emerged foliage reaches a height of six to eight inches above the soil line.
At this stage, carefully add more soil or compost around the stems until only the top few inches of leaves remain exposed. Repeat this hilling process every time the foliage grows another six to eight inches. Continue until the soil level is approximately two inches from the top rim of the grow bag. Once the bag is full, the hilling process is complete.
Ongoing Care and Maintenance
Consistent moisture levels are paramount for healthy tuber development. Grow bags tend to dry out more quickly than in-ground gardens, so regular monitoring is required. Aim to provide the plants with about one to two inches of water per week, adjusting for rainfall and checking the soil moisture several inches down. Avoid overwatering, which can lead to root rot or create an environment conducive to fungal diseases like late blight.
Potatoes are heavy feeders and benefit from supplemental nutrients after the initial growth phase. Once the plants reach the six to eight-inch height, begin a routine fertilization schedule. The fertilizer blend should be low in nitrogen (N) but higher in phosphorus (P) and potassium (K), such as a 5-10-10 ratio. Excessive nitrogen encourages lush leaf growth at the expense of developing the underground tubers.
Apply a liquid feed or a granular side-dressing every two to three weeks to sustain the plant through the bulking phase. While caring for the plants, inspect the foliage regularly for common pests like the Colorado potato beetle or signs of fungal diseases. Because grow bags are mobile, they can be temporarily moved out of areas of extreme heat to prevent the soil from overheating, which stresses the plants.
Harvesting Your Potato Crop
Knowing when to harvest depends on the type of potato desired. For “new potatoes,” you can begin harvesting approximately seven to nine weeks after planting, generally when the plants start to flower. Gently reach into the soil near the edge of the bag to feel for small tubers, taking only what is needed and leaving the rest to continue growing.
For a harvest of mature “storage potatoes,” wait until the plant foliage begins to yellow, wilt, and completely die back. Stop all watering two weeks before this anticipated dieback to help toughen the skins. Wait an additional two weeks after the foliage has fully died to allow the skins to fully set before harvesting.
Instead of digging through hard soil, you can simply tip the entire bag onto a tarp or wheelbarrow to expose the contents. After collection, allow the potatoes to cure for one to two weeks in a cool, dark, and well-ventilated area. Curing heals any small nicks or bruises, ensuring the potatoes are ready for long-term storage.