Hello,
I live in a small house and now have 5 indoor bonsai that I am really enjoying, one of which is a bilobed Grewia (Grewia Biloba) I got for Christmas.
So I set up a stand by the southern window, beside the door to my porch where the rest bonsai tools and pots are. In the past week I think I have gone out to the porch a few too many times because the leaves on the tree are turning yellow and all dropping. Since that happened, I have moved the tree away from the door and kept a close eye on the tree. The tree has had more and more leaves turning yellow and falling. Is there anything I should do? Did I just kill my bonsai?
#SaveTheBonsai
No, Maybe, Yes.
You shouldn't keep indoor bonsai's near doors, or windows that you open in the cold months. The draft can kill them.
If you grow trees by windows or doors in the winter months that you don't open, they would benefit from bottom heat to keep the root system warm.
Now, as far as your yellowing leaves are concerned..
Some trees loose their leaves when they get moved from location to location if the spots are different in light/heat/humidty.
Some trees loose their leaves if they get over watered.
All trees will eventually loose their leaves if neglected and underwatered.
Post a photo of your problem trees, and possibly your growing location.
Also as mentioned include your location.
I have a bilobed grewia, and i've only really seen them in Southern Ontario because there's one nursery that carries them here, and it's pretty much the only nursery in the GTA that has a decent selection imported beginner bonsai.
So here's what I'm thinking.
Assuming you're from the GTA, and you got the Grewia from Kims, the consistent diffused natural light with supplimental, and warm temperature that their greenhouse provides is completely different to where you're growing yours: drafty area that receives light from 8ish until 5ish from one side only without any supplimental lighting. Since you're in a house most likely with forced air, your general humidity is low. Unlike the greenhouse which is high in humidity, as they grow orchids in it as well. So hopefully your tree isn't dead, and it's just shocked and adjusting to the light and temperature conditions. Don't over water it whatever you do. Don't leave it in a drafty location. If it's alive you should see some new growth popping out in about 2 weeks. Put it in a adequate position and don't move it. Let it acclimatize.
My bilobed grewia, if left dry for more than one day will shed half of it's leaves.. it's very very fickle. If left very very wet for more than a couple days, will start to shed. It has a thin bark, so is susceptible to rot. Mine doesn't like high moisture so I don't spray it as much as my ficus'.