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Proper winter storage of tender bulbs helps plants bloom again in spring

Media contact:

Robert E. Thomas
Information Specialist
University of Missouri Cooperative Media Group
Phone: 573-882-2480
E-Mail: thomasr@missouri.edu

Published: Wednesday, September 30, 2009

Story source:

David H. Trinklein, 573-882-9631

COLUMBIA, Mo.—When storing tender ornamental plant bulbs, proper temperature and moisture are critical to ensuring they survive the winter and bloom again in the spring, said a University of Missouri horticulturist.

“Since the bulbs of many species are not winter-hardy at our latitude, they should be dug up and stored soon after the tops are killed by freezing temperatures,” said David Trinklein.

Average first frost in Missouri ranges from Oct. 10 in the northernmost counties to Nov. 4 in parts of the Bootheel, according to MU’s Missouri Climate Center.

Different types of bulbs have different moisture and temperature needs for winter storage, Trinklein said.

Tuberous begonia: Dig up immediately after the first killing frost. Allow the tops to remain on the tubers and spread them in a warm, dry location. Let dry for about 14 days, then remove the tops and store the tubers at 40-50 degrees in peat moss, vermiculite or sawdust that is slightly moist.

Canna: Cut to the ground after the tops have frozen back. Turn the tubers upside down after digging and allow them to dry outdoors for several hours. This allows the cut surface to begin to heal. Store in a well–ventilated room to dry for several days, but not to the point that the tubers begin to shrivel. Place the tubers in dry peat moss, vermiculite or sand and store them where it is cool but above freezing.

Dahlia: Roots of dahlias are more challenging due to their thin skin, which causes them to dry excessively unless protected. When digging dahlia roots, take care not to damage the narrow neck between the crown and the thicker storage root. Allow the roots to dry for several days in a warm, dry location before packing them in boxes filled with moistened peat moss or vermiculite. Store at about 40 degrees.

Caladium and elephant ear: After digging, remove excess soil from the bulbs or tubers but do not wash them. Allow them to dry in a warm, dry location with good air circulation for seven to 10 days. After drying, pull off the foliage of the caladiums, but cut off the foliage of the elephant ear about two inches above the bulb. These are tropical plants, so store at about 60 degrees in dry peat moss or vermiculite.

Check the bulbs periodically during winter and remove any bulbs that might be diseased. Also check the moisture of the packing medium. Too much or too little moisture can damage the bulbs. “As a general rule, it is better to error on the dry side rather than the wet,” Trinklein said.

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