Cedar Valley Arboretum & Botanic Gardens

Winter Sojourn

leave a comment »

Picture 004I was just reading online where one gardener described the months ahead as our “winter sojourn.”  This is much nicer than my mom’s description of winter as the “vortex of terror!”  I’ll try to keep an upbeat attitude for now, but it seems as we get closer and closer to spring, our hibernation seems more and more like a terror! 


Is your garden all put to bed?  Any last chores to do?   I still have cannas to dig at The Arboretum.


Cannas are grown (and loved) in Iowa for the splashy, tropical feel they bring to garden and patio containers.  The broad leaves vary in color from dark green to red to maroon with many variegations in between.  The flowers are usually red, yellow or orange.


Cannas grow from rhizomes, a horizontal stem of a plant grown underground with roots and shoots.  (Harvested ginger is a rhizome.)  Since cannas cannot overwinter in Iowa, we must lift these rhizomes each fall and overwinter indoors.  Plants with fleshy storage structures like this (also include bulbs, corms, tubers and roots) are called “tender bulbs.”


Interesting fact: Canna rhizomes are an excellent source of starch for humans and livestock and were once a staple food product in parts of the world.


So how do you overwinter cannas?  After the first frost, cut back the foliage to a few inches above the soil.  Using a pitchfork or shovel, lift the rhizomes out of the soil being sure to dig out far enough as to not pierce the rhizome.


There are differing opinions on cleaning and storage, and really, depends on how much effort you are willing to put into your cannas.  I have had good luck shaking off extra soil from the rhizomes and throwing them in a cardboard box in the basement.  Other years I have done a more thorough cleaning job and then let them dry out for a few days in the garage before storing for the winter.  I layered the rhizomes in a box with newspaper (you could use peat moss, wood shavings or similar material).


The technique can vary, but a few points to keep in mind:

  • Cool temperatures, but not freezing.  Ideal temperatures are between 50 and 60 degrees.  The rhizomes can start to deteriorate lower than 45 degrees.
  • Moisture.  A bit of moisture goes a long way in keeping the rhizomes from drying out, but too much creates an environment for rotting.
  • Air circulation.  A bit of air movement will also help in the rhizomes from not rotting.


After chances of frost have passed for the spring, again plant your canna outdoors.  Healthy rhizomes will be firm to the touch.  Throw away any rhizomes that are soft or mushy.  And remember, no overwintering technique is foolproof.  If you do not have success, don’t be afraid try again the next year!


See you in the gardens.


Written by cedarvalleyarboretum

November 16, 2009 at 6:01 pm

Posted in Uncategorized

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: