Chinese Elm Bonsai
I have had my Chinese Elm for about 2 years. It has repeatedly dropped all its leaves and then recovered. I thought it was root bound-but upon repotting it found the roots healthy. It did have spider mites last fall so I treated it for that. I travel a lot and for some time thought that the automatic watering system was not giving it enough water as the soil was almost always dry when the leaf drop occurred. It is in a slow recovery mode again with scraggly leaves that start and die and others that are hanging on. I’m totally puzzled? Suggestions?
Wayne County Michigan
Indoor bonsai are typically tropical species which need no dormant or cold period-
North temperate zone species need a cold period, which helps initiate dormancy. This includes elms. —
I believe your elm is trying to go dormant, just like outdoor elms. Right now it is too cold to acclimate the elm to the outside. You will have to try and keep it moist but not soaking, and not necessarily leafed out, until spring. Previous leaf drops during spring or summer are probably due to the roots being dry for too long.
You can check with a local bonsai supplier, garden center that offers bonsai, or bonsai club for suggestions on how they maintain their bonsai elms. An unheated space that stays above 30 degrees or so would be the best place to over-winter the elm- keeping roots moist. Do not fertilize. Check your potting medium to be sure it drains well, and that roots never stand in water. Plan to gradually move the elm outdoors next spring when it warms up, like you would a house plant. Follow the recommendations as outlined in the second link, above, and prepare it to overwinter in a protected outdoor or unheated space next fall.
Elms in pots need extra protection but, elms in the ground are capable of surviving to about -20 to -40 F, if the seed source for the plant was from the North, and once the plant is properly acclimated. Here is an article that explains-
If you search the internet for Michigan bonsai clubs several will turn up. They may have some suggestions for you, especially about overwintering here in Michigan. Thanks for using our service.