Each year I would plant a few tender bulbs for their summer blooms or dramatic leaves. They are a wonderful addition to the home garden.
The term tender bulb refers to bulbs, corms, tubers, and rhizomes that will be winter killed by our Zone 5 winters. These tender bulbs need to be removed from the ground before winter sets in. A few of the more commonly grown tender bulbs are Canna, Tuberous Begonia, Gladiolus, Caladium, Belladonna Lilies, Elephant Ears, and Crocosmia.
Most tender bulbs are dug after the first frost has killed the tops and temperatures have not dropped enough to freeze the ground. Others such as Belladonna Lilies, Caladiums, Elephant Ears (Alocasia and Colocasia), and Callas, are removed before air temperatures regularly drop below 45 degrees.
Start by gathering containers to hold your bulbs as you dig them. I tag each container with the name of the bulbs and color, reusing this tag for final storage. The thin plastic slats of an old venetian blind work perfectly and are easily cut to size. Use a permanent marker for writing.
Lift bulbs carefully using a spading fork. Loosen the soil by working around all sides of the bulb, giving it a wide berth to avoid damage to the root structure. When you remove the bulb from the ground, gently loosen or shake off excess soil. Cut off the tops to within an inch of the bulb, and place it in the container with its tag.
Cleaning comes next. An easy method that keeps things relatively clean and saves my back is to lay a large piece of hardware cloth over the top of an empty garbage can. Put the bulbs on top and gently hose them off; the water and soil fall into the can. This set-up is located beside the compost pile—periodically tip the garbage can with its soil and water into the heap. With Gladiolus, break off and retain new fleshy corms from the older corm, and discard the older into the compost as well.
Before storing, inspect bulbs for damage. It is good practice to dust the bulbs with an insecticidal fungicide before storing. Read the package label to be sure it will work for your bulbs.
Storing Gladiolus and similar corms is little different. They will need to dry for about three weeks. Afterwards, store them in a paper bag in a cool dry environment.
Most other tender bulbs are stored in open containers, covered in vermiculite (my favorite) or sphagnum peat and stored in the dark at around 45-50 degrees. The area must also be low in humidity and free of ethylene gas produced by apples and other fruits.
Because tender bulbs in storage are still living things, you will need to inspect them periodically during the hibernation period. If bulbs look like they are shriveling, mist lightly. Remove those that look diseased and cut away soft rotting sections from fleshy tubers.
For more information on specific bulbs and storage requirements, see the extension bulletin “Storing Tender Bulbs and Bulb Like Structures” printed by University of Minnesota Extension.