How to overwinter potted Japanese maple
Hi, I have a Japanese maple (Acer palmatum) sapling in a 10-12 inch pot that I purchased last spring and moved to a bigger pot once. The tree is about 2-3 feet tall. What is the best way to care for it over the winter--keep it indoors or keep it outdoors in a protected area? If I keep it outdoors, what are some steps I can take to protect it? Thanks, Sheila
Ramsey County Minnesota
In Minnesota, it's very difficult to overwinter plants outdoors in containers. This might especially be true for your Japanese Maple if it is a variety that is rated for growing zone 5. If this is true, the tree will not survive the winter outside. If you have a maple rated for growing zones 3 or 4, the survival prospects are slightly better. However, see the following two publications about how even such varieties may experience difficulty being outside over the winter.
As these publications suggest, putting your pot into the ground would be better than leaving it above ground. Unfortunately given our recent night temperatures, frozen ground may preclude this route. You then should consider moving the pot inside to an unheated place that will remain above freezing during the winter. The goal would be to maintain a relatively constant soil temperature in the pot and avoid freeze/thaw cycles. The following three publications will elaborate on this point:
We believe that the bottom line is that either burying your pot or bringing it indoors are your two best alternatives.