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Dig deep to prep for garden next year

Jessica Walliser
| Friday, Oct. 25, 2013, 8:57 p.m.
Elephant ears are one of many tender bulbs that must be dug out of the garden and stored indoors for the winter.
Jessica Walliser
Elephant ears are one of many tender bulbs that must be dug out of the garden and stored indoors for the winter.

The next few weeks will be spent preparing my garden for the coming winter. While I leave the vast majority of my flowering perennials standing through the winter to provide food and habitat for birds and beneficial insects, I do take the time to pull out any frost-singed annuals and deconstruct my container plantings.

But by far, the biggest autumn chore in my garden is digging up and storing all my tender bulbs and tubers. Dahlias, cannas, tuberous begonias, caladiums and elephant ears are just a handful of the many common garden plants that grow from tuberous roots or bulbs that will not survive winter's freezing temperatures. To enable their return to next year's garden, I need to dig them up and store them inside until spring.

It is best to begin this process before, or just after, our first frost. For dahlias, cut any frost-blackened foliage off about 2 inches above the soil surface. Cover the cut stem with a piece of aluminum foil to keep water from travelling down to the bulb and causing rot. Allow the tuber to rest in the soil for a week or two before carefully digging it up.

Once it is out of the ground, brush off any excess dirt with your fingers and remove the piece of foil. The tuber can be split at this time, using a clean, sharp knife. Each new tuber needs to have at least one “eye” (much like the eye on a potato that's been left in the cupboard too long). Some folks prefer to divide their dahlia tubers in the spring before replanting them while others prefer to divide at storage time. Either method is fine. Place the freshly dug tubers on a plastic tray or old window screen in the garage or basement for a day or two to let them dry out a bit. Before packing them away, label each variety with a tag, or by writing directly on the tuber with a permanent marker. Now, they are ready for storage.

For cannas, caladiums, tuberous begonias, elephant ears and other tender bulbs, cut the foliage down to ground level and dig up the bulb. Brush off the excess dirt with a soft brush or your fingers. They, too, can be laid out on screens or trays in the garage for a day or two before storing. You can break or cut the roots apart before storage if you wish. And don't forget to label them properly.

To store tubers and bulbs, you have several options. At my house, I use plastic storage tubs with a dozen or so half-inch ventilation holes cut in the sides and lid. Some gardeners prefer to use cardboard boxes or wooden crates lined with newspaper. Any of these choices is fine.

Place a 2-inch layer of dry peat moss or vermiculite into the bottom of the container, then position a single layer of bulbs and tubers on top of it, being careful to leave space around each tuber to prevent the spread of any rot that should occur. Cover the roots with another few inches of peat moss or vermiculite then continue adding layers of bulbs topped with substrate until you reach the top of the bin or box.

Place the box i n a cool, dry place such as a basement, root cellar or garage for the winter. If you'd like, you can check the bulbs for rot every six to eight weeks by carefully opening the storage container and feeling for soft spots on the bulbs. Bulb rot can cause an odor as well, so a good sniff-test can often detect a rotten bulb. If any do show signs of infection, discard them promptly and re-store the remaining bulbs and tubers in a new container with new substrate.

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio. She is the author of several gardening books, including “Grow Organic” and “Good Bug, Bad Bug.” Her website is

Send your gardening or landscaping questions to or The Good Earth, 503 Martindale St., 3rd Floor, D.L. Clark Building, Pittsburgh, PA 15212.

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