Dakota gardener: Save your bulbs for next year

Esther McGinnis, Horticulturist
North Dakota State University Extension
To preserve plants for next year and to save money, consider lifting and overwintering your expensive tender bulbs.

We live in an era of reduce, reuse and recycle. We also have a Midwestern ethic of thriftiness. Can you apply this ethic to your flower garden? Yes!

In a short period of time, our annual flowers will be killed by fall frost if left in the garden. To preserve plants for next year and to save money, consider lifting and overwintering your expensive tender bulbs.

Tender bulbs is a generic term for summer-blooming plants from the tropics and subtropics that have fleshy underground storage structures such as bulbs, rhizomes, tubers and corms. Gardeners plant them in late spring after the danger of frost has passed. Examples include dahlias, cannas, caladiums and gladiolus.

After the first light frost has killed the aboveground foliage, dig up the root system using a pitch fork or shovel. Carefully dig around the perimeter of the plant, making sure not to wound the underground structures. Wounds allow entry points for bacteria and fungi that may cause rotting over the winter.

Cut off the foliage and brush off excess dirt. A garden hose can be used to wash off dirt for most tender bulbs but not gladiolus. More on gladiolus in a minute.

Cannas, caladiums and dahlias should be cured for one to three days. Curing means allowing the underground structures to dry indoors at room temperature for one to three days. Discard any structures that are rotting or infested with insects.

Gladiolus corms are a special type of tender bulb that should not be washed or else they will rot. Corms should be allowed to cure for three weeks before storage.

All tender bulbs should be marked with their species and cultivar. An easy way to do this is to write the name on the bulb using a permanent marker. Tags may also be used.

Place the tender bulbs in a well-ventilated container such as a cardboard box. Plastic containers should be avoided because they keep the humidity too high around the bulbs.

The container should be filled with a dry media such as peat moss, vermiculite or sawdust. To prevent rotting, dust the bulbs with an approved fungicide and place in the media with space between the bulbs.

Store the bulbs for the winter at temperatures between 40 degrees and 50 degrees Fahrenheit. Finding an appropriate storage area can be challenging to prevent the bulbs from freezing or rotting. A heated garage works well if the temperature is regulated. Alternatively, find the coolest and darkest corner of your basement.

In early April, pot up the bulbs in small containers to coax the bulbs out of dormancy. These tender plants can be transplanted into the garden in mid- to late-May depending on your average last frost date.

Tender bulbs should not be confused with hardy bulbs. Hardy bulbs are planted in the fall and include crocus, tulips, hyacinths and daffodils. These hardy bulbs can remain in the ground over the winter.

For more information about gardening, contact your local NDSU Extension agent. Find the Extension office for your county at https://www.ag.ndsu.edu/extension/directory/counties.