Summer flowering tropicals, such as begonias, cannas, dahlias and gladiolus are considered tender bulbs in our climate. They won’t survive our winter, if you leave them in the ground. Some gardeners choose to treat these summer flowering favorites as annuals and plant new bulbs every year. Another choice is to dig up each bulb and store them until its warm enough to plant next spring. Here are some things to do if you decide to store your bulbs. Note: the word "bulb" is being used as a generic term for dahlia tubers, gladiolus corms, canna lily rhizomes and tuberous begonia tubers. After first frost, when the leaves turn black, is the time to dig tender bulbs.
Cut the remaining foliage back to about 5"-6". You can cut the foliage back before you dig the bulbs or afterwards, whichever is convenient. Rinse each bulb off to remove excess soil then let dry in a shady spot. The packing material will help stabilize the temperature. Bulbs need attention during storage, so check on them every week or so. Make sure they don’t dry out and keep an eye out for damage or disease that may show up in storage. If the bulbs look like they are shriveling up, mist the packing material to add moisture. Your bulbs may have increased in size during the growing season. Wait until spring to divide dahlias and cannas.