Growing potatoes in grow bags has become a practical solution for gardeners facing soil and pest challenges, according to advice shared by the UC Master Gardeners of Contra Costa County. Over several seasons, local gardeners have experimented with various methods, encountering issues such as poor clay soil, disease from grocery store potatoes, and damage from moles and gophers. The transition to raised beds offered some success but also led to overcrowding and small yields when too many seed potatoes were planted close together.
Container growing with burlap bags showed promise but presented new problems: the bags deteriorated before harvest, exposing potatoes to sunlight and making them toxic. More recently, using specialized grow bags has produced better results, yielding a variety of healthy potatoes. Grow bags are noted for being reusable and permeable, which helps prevent waterlogging and allows roots to breathe. They are also suitable for small spaces.
One advantage of grow bags is their flexibility during the “hilling” process. The top can be rolled down at planting time and gradually unrolled as more soil is added while plants grow taller. This method encourages tuber production along buried stems.
Gardeners are advised to use certified seed potatoes rather than grocery store varieties to avoid introducing diseases into their gardens. Certified seeds can be purchased from reputable nurseries or online sources. Potatoes should be planted in sandy loam soil or a well-prepared mix with compost, as they are shallow-rooted crops.
Fertilizer labeled 5‐10‐5 or 10‐10‐5 should be mixed into the soil before planting and applied lightly throughout the growing season after plants reach three to four inches tall. Planting should occur after frost danger has passed—typically between February and April—with an option for a second crop in July or August if conditions allow.
Soil preparation involves moistening a good planting mix with compost and fertilizer; only half is used on planting day, with the remainder reserved for hilling as plants grow. Seed potatoes can be pre-sprouted (a process called chitting) for faster growth but will eventually sprout even without this step.
Potato care includes regular watering since grow bags dry out quickly; maintaining consistent moisture is important to prevent knobby or hollow tubers. A drip irrigation system is recommended if available. Mulching helps retain moisture in hot weather.
Pest management remains important due to threats like aphids, flea beetles, slugs, snails, and potato tuberworms. Regular monitoring under leaves and along stems is suggested for early detection of infestations. Further guidance on pest control is available from UC’s Integrated Pest Management program at https://ipm.ucanr.edu/home-and-landscape/potato/index.html.
Harvest typically occurs when foliage yellows and stems wilt late in the season; watering should stop at this stage before harvesting after one or two weeks. Yields may range from 7 pounds up to 13 pounds per bag in good years.
After harvesting, curing potatoes by storing them in a cool (50-60°F), dark place for about two weeks helps toughen skins for longer storage life. Potatoes should not be washed before storage; damaged ones should be eaten promptly rather than stored.
For additional resources on potato cultivation—including tips specific to winter crops—gardeners can consult UC Master Gardener publications at https://ucanr.edu/site/uc-master-gardener-program-contra-costa-county/article/potatoes-are-perfect-winter-crop or view a recent webinar at https://youtu.be/tnWrn1XscD0?si=C7UAyikfrrtAxlAb.
The Help Desk of the UC Master Gardeners of Contra Costa County offers further assistance for those seeking advice tailored to local conditions.
