Storing tender bulbs

UNIVERSITY OF MINNESOTA EXTENSION - www.extension.umn.edu

The only thing I do not like about autumn is that some of my favorite flowers reach the end of the bloom cycle. The important thing to remember is that if these are tender bulbs, they need to be put into proper storage. This will ensure that you will be able to enjoy some of your favorite flowers and save some money next spring.

Tender bulbs include tuberous begonia, freesia, dahlias, gladiolus, caladiums, canna, Oxalis and calla lilies, and all should be stored indoors for winter or they will not survive the cold.

Dig them up

The general rule of thumb is to dig your tender bulbs out of your gardens after the leaves begin to dry up or are killed by frost.

Once the timing is right, carefully dig up the tender bulbs. Use a fork or spade to gently loosen the roots several inches away from the plant’s base. It usually works best to loosen the soil on all sides of the plant before trying to lift up the clump. It is important to avoid cutting, breaking or “skinning” the fleshy bulb. If you damage the bulb it is more susceptible to disease or rot.

Clean and dry them

After the bulbs have been dug, clean them. Most plants need a gentle wash, but gladiolus corms store best if left unwashed and simply let to dry out. Be sure to dust off any soil before putting them in storage. 

Then, the bulbs will need to cure or dry. Curing time varies depending on the species. Dahlias, cannas, callas and caladiums have a short curing period of only one to three days. Gladiolus, oxalis and freesia require a longer curing period of approximately three weeks. Gladiolus should cure in temperatures of approximately 60°F to 70°F.

All tender bulbs should be stored out of direct sunlight and in well-ventilated areas while drying.

Inspect for pests

Next, be sure to inspect for pests before storing them away. Pests include both insects and fungi or other diseases.

You may consider lightly dusting with an insecticide or fungicide according to the product’s label to avoid pests over winter.

Put them away

Long winters can make it difficult to remember exactly which bulbs are which come spring. Label your bulbs as you put them in their final storage space. You can write directly on the bulb with a soft-tipped marker.

Finally, choose a location that is going to have a consistent temperature appropriate for your bulbs' storage.

• Freesia, gladiolus and oxalis should be stored at 35° to 40° F.
• Cannas and dahlias should be stored at 40° to 50° F.
• Tuberous begonia, caladium, and calla lily should be stored at 50° to 55° F.

Throughout the winter you will want to check in on your bulbs to ensure there are no signs of rot. Remove anything that shows signs of rot or decay before all of your bulbs and all of your work are lost.