Storing Summer Bulbs

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Donald Buma, Norfolk Botanical Garden Executive Director

Caladium 'White Queen'As cold weather approaches, it is time to begin planning to store summer bulbs such as gladiolus, caladium and dahlia.  These plants need to be dug up and stored so they can be planted next year. These plants should be dug after frost has caused the tops to die back.  Or, you can cut back the foliage if you want to move the plants so that you can plant pansies, other winter annuals or spring blooming bulbs.

After you dig up the bulbs, actually not true bulbs but more on that later, allow them to dry for about a week in a shady, well-ventilated site such as a garage or tool shed. Remove any excess soil and pack them in peat moss, vermiculite or perlite. Make sure the bulbs don’t touch so that if one decays, the rot doesn’t spread to its neighbors. Dusting them with fungicide before storage will also help prevent them from rotting.  It is best that storage temperatures be near 40 degrees, 50-60 degrees for caladium.

The terminology “bulb” for these plants is one of convenience rather than horticultural accuracy.  True bulbs are shortened stems with thick, fleshy leaf scales.  These include daffodils and onions.  The summer bulbs listed above are  corms, tubers and tuberous roots.

Tubers are enlarged or swollen underground stems.  The common potato is a tuber as are caladiums.  Plants classified as corms, solid compressed stems without fleshy scales, include gladiolus and crocus.  Dahlias are plants with tuberous roots, which are swollen fleshy roots.  The sweet potato is also classified as a tuberous rooted plant.  Whether bulb, corm or tuber, they are great ornamental plants and need proper winter care.