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Store summer bulbs for winter
Rip Winkel

This week I have received a number of calls about what to do with those bulbs that cannot over-winter here in Kansas. The cold season is approaching, in fact has already zapped many of our garden plants with the first freeze of the fall just this last past weekend. Now would be a time to start thinking about storing those bulbs that will not survive Kansas winters if you have not done so already. Bulbs, such as gladiolus, caladium, dahlia, tuberous begonia, calla lily, and canna lily, need to be dug up and stored in a protected area so they can be replanted again next year. 

The bulbs you plan on keeping should be dug up after frost has at least partially browned the foliage. Allow them to dry for about a week in a shady, well-ventilated site such as a garage. Freezing temperatures should be avoided. Remove excess soil and pack them in peat moss, vermiculite or perlite. It is important that the bulbs don’t touch one another so that if one decays, the rot does not spread. Dusting them with fungicide before storage will help prevent rotting.

Caladium should be stored between 50 and 60 degrees. The other bulbs mentioned should be stored as near 40 degrees as possible. Finding a good spot to store the bulbs may be difficult. Some people place them against a basement wall farthest from the furnace and insulate them so the wall keeps them cool. 

Did you know, however, the “bulbs” or the plants mentioned in the list above are not true bulbs? A true bulb is an underground stem with fleshy, scale-like layers surrounding a center bud. Think of the layers when you peel an onion. The scales are food storing leaf bases and they are attached to what is called a basil plate. It’s actually the bottom of the bulb from which the roots grow out. 

Canna and calla lilies, however, have rootlike structures called rhizomes. These are horizontal, underground plant stems that produce new shoots and root systems. Rhizomes are used to store starches and proteins, enabling these plants to survive underground in unfavorable seasons. Other rhizomes are irises, bamboo and lily of the valley.

Caladium and many begonias have tubers. Tubers are yet another type of swollen stem. There is no basil plate like that of a true bulb, and the outside skin tends to be leathery. Tubers have eyes, or growth nodes, from which the new plants grow. Examples of tubers are anemones, cyclamens, peonies and, of course, potatoes. 

Gladiolus is a corm. Corms are also stems generally round in shape, where the plant grows out of an indention at the top of the structure. Roots develop out from the top of the corm into the ground. And just like the rhizome and tuber, this structure stores nutrients and water for use in future need.  

The dahlia is a tuberous rooted plant. Unlike the three rootlike structures above, tuberous roots are a true root, thickened to store nutrients. The fibrous roots absorb water and nutrients, to be stored in the swollen parts. Tuberous roots grow in a cluster, with the tuberous portions radiating out from a central point. Day lilies also have tuberous roots.


Rip Winkel is the horticulture agent with K-State Research and Extension – Cottonwood District. Contact him by email at or call either 785-682-9430, or 620-793-1910.