The practice of digging up and storing bulbs, often called lifting, is necessary for many garden varieties. Bulbs can be dug up and stored, particularly tender varieties that cannot survive freezing winter temperatures outdoors. This process protects non-hardy plants and serves as a valuable maintenance step for managing overcrowded beds or inspecting plant health. Successful preservation depends on proper timing and creating an appropriate environment after removal.
Identifying Bulbs That Require Lifting
Garden bulbs are categorized into two groups based on winter hardiness: hardy and tender. Hardy bulbs (e.g., tulips, daffodils, and hyacinths) withstand freezing temperatures and are generally left in the ground year-round. They require a natural cold period, or vernalization, for flower formation the following spring.
Tender bulbs (e.g., dahlias, gladiolus corms, cannas, and tuberous begonias) originate from warmer climates. They cannot survive a hard frost and will rot or freeze if left exposed to harsh winter conditions. Lifting these tender varieties before the first hard frost is required for their survival and re-blooming.
A secondary reason for lifting otherwise hardy plants is cultural maintenance. Over several seasons, bulbs multiply, leading to overcrowding that results in smaller blooms and weaker plants. Digging and dividing crowded hardy bulbs every few years rejuvenates the planting and allows inspection for signs of disease or pests before replanting.
The Process of Preparing and Curing
Successful preparation begins with proper timing. Tender bulbs must be lifted just after the foliage has yellowed and died back naturally, or before the ground freezes solid from the first hard frost. Allowing the foliage to fade ensures the plant has transferred maximum energy reserves back into the storage structure for the next season.
Use a garden fork rather than a spade to minimize the risk of piercing the delicate structure during the excavation process. Insert the tool a safe distance from the main stem and gently lever it to lift the entire clump of soil, roots, and bulb. Once lifted, carefully brush or rinse away excess soil, taking care not to damage the protective outer skin, or tunic.
The next step is “curing,” a controlled drying period that hardens the bulb’s outer layers. Curing reduces internal moisture content, preventing fungal pathogens and rot during long-term storage. The bulbs must be placed in a single layer in a dark, dry location with good air circulation for a period of several days to two weeks.
Ideal curing conditions involve temperatures between 60 and 70 degrees Fahrenheit, which facilitates surface moisture evaporation and the formation of a tough, protective skin. During this time, trim back remaining stalks and roots, leaving only a short stub of the stem. The bulb is ready for final storage when the outer layer feels papery and firm to the touch.
Creating the Ideal Storage Environment
Once the bulbs are properly cured and dried, the focus shifts to establishing a consistent, protective storage environment that mimics natural dormancy. The temperature of the storage location is paramount for survival, requiring a cool but non-freezing range, typically between 35 and 50 degrees Fahrenheit. Temperatures below 32 degrees Fahrenheit will cause the internal cell structure to freeze and rupture, rendering the bulb non-viable for the next spring.
Proper air circulation and ventilation are also required to prevent the accumulation of moisture and gases that can encourage mold or premature sprouting. Bulbs should never be stored in airtight plastic bags or containers that trap humidity, which creates a perfect environment for fungal growth. Instead, perforated plastic crates, mesh bags, or cardboard boxes are preferred containers that allow for adequate gaseous exchange.
A surrounding storage medium is used to cushion the bulbs and regulate the humidity immediately surrounding them. Common materials absorb excess moisture and prevent the bulbs from touching each other. These materials include:
- Peat moss
- Vermiculite
- Dry wood shavings
- Shredded newspaper
The medium must be kept just barely moist, preventing the bulbs from completely desiccating and shriveling, while still inhibiting rot.
The goal of the storage medium is to maintain a relative humidity level of approximately 60 to 70 percent within the container. Throughout the winter, inspect the stored bulbs periodically for any signs of trouble. Soft spots, unusual discoloration, or fuzzy mold indicate a problem, and the affected bulb should be removed immediately to prevent the spread of pathogens to healthy stock.