Sharon sent this timely question from Colorado:
“I live in an apartment. I love catalpa trees so bought one this year which is planted in a hard plastic pot that is sitting on my deck. I live in Longmont, CO and am wondering if there is anything I need to do to winterize the tree? I just transplanted it into a larger pot from the black one it was in when I bought it. It grew about 4 feet since spring.”
As kids, we called these “toby trees” and recognized them most for their long, green-bean-like seed pods in late summer.
Now back to Sharon’s question…
Nurserymen face the same situation heading into winter with unsold potted trees and shrubs.
Generally speaking, roots are not as cold tolerant as the tops of trees and shrubs. For example, the top of a tree or shrub might be hardy to 10-degrees Fahrenheit while its root system may only be hardy to 20-degrees Fahrenheit.
This is why nurseries typically “heel-in” plants over the winter, or bunch potted plants close together in a hoop house, under low plastic cover or straw, or whatever works to insulate the root system from temperature fluctuations and severe winter cold. Mice become a problem if they get in to nibble on these plants.
Pots can also be buried in shredded wood mulch or straw. Some gardeners overwinter plants in unheated garages. Your best choice is to find a place where you can bury the potted tree in the ground just as if you were planting it. The pot will get muddy, but it can be scrubbed-off in spring when the Catalpa comes home to your deck.
For those unfamiliar with the beautiful blossoms and other unique characteristics of Catalpa speciosa, you will find more photos on the Missouri Botanical Garden webpage here.