Some of our favorite garden flowers in Minnesota are tender bulbs and have to be dug up in autumn so we can overwinter the bulbs and replant them next spring to enjoy the blooms again. This will save the gardener some money also.

Tender bulbs include caladiums, calla lilies, cannas, dahlias, elephant ears, freesia, gladiolus, oxalis, pineapple lilies and tuberous begonias.

The general rule of thumb is to dig your tender bulbs out of your garden after the leaves begin to dry up or they are killed by frost. Using a fork or spade, dig them carefully to gently loosen the soil from around the roots. Dig several inches away from the plant’s base. For bigger clumps, it works best to loosen the soil from each side of the bulbs before trying to lift them up. 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.

After the bulbs have been dug, clean them. Most plants need a gentle wash, but gladiolus corms store best if left unwashed and simple left to dry out. Break off the old corm from the gladiolus bulb before storage. Be sure to dust off any soil before storage.

Then the bulbs 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 to 70 degrees Fahrenheit. All tender bulbs should be stored out of direct sunlight and in well-ventilated areas while drying.

Next be sure to inspect for pest (insects, fungi or other diseases) before storing. You may consider lightly dusting with an insecticide or fungicide according to the product’s label to avoid pests over winter.

Label the bulbs when you put them in final storage so you remember exactly which bulbs you are working with. You can write directly on the bulb with a soft-tipped marker. Then 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 degrees F

• Cannas and dahlia should be stored at 40 to 50 degrees F

• Tuberous begonia, caladium and calla lilies should be stored at 50 to 55 degrees F

Throughout the winter, it is good to check occasionally to ensure that there isn’t anything showing signs of rot or decay. Remove any problem bulbs.

Information taken from article by Katie Drewitz, U of MN Extension Educator, October, 2023