Is it okay to keep small seedlings (or any bonsai) in a small conservatory? I've heard that it's best to keep native tree species outside to allow them to change with the seasons, but I feel more comfortable keeping the tiniest plants indoors... I live in the UK and am a complete newbie to Bonsai btw

Trees need to be outside, period.
99% of the help my tree is dying questions here are from people with trees that are inside.
Native trees..around here they dont go hiding inside when temps drop or when its wet outside....

Thanks for the help!

Look at the tree species and where it originated. If the winter climate there is a lot like you local winter climate, leave them outside. If it is more like inside your house, bring them in.

If the trees are native then they must be outside, there is no need to protect from anything. They will survive perfectly well in the winters we have in this country, but will not if kept inside, it is as simple as that.

Just to clarify, Does that include conservatories as well?

Arn wrote: Just to clarify, Does that include conservatories as well?

..do you see trees around you migrate into conservatories in winter?

Jk of course- use the conservatory when a period of deep and long frost is anounced. Then the rootball of our trees can become completely frozen ( because they are in a container/pot). Place them in the conservatory, maybe even under some bubble plastic. Don't forget to get them out again if temps are not that harsh anymore because temps in the conservatory can become rapidly postive/warm even in winter, leading the tree to think its time to come out of dormancy already.

I keep all my trees in unheated greenhouse in winter. Yes they come out of dormancy earlier. That is about the same time as the same species comes out of dormancy in southern Germany. I do Think that this longer grow season is good for my trees.

It probably depends on the tree.

We have a pretty long growing season here, and a very short dormant season, and I can't get larches to survive. They want a long period of frost, which is only available here in the refrigerator.

Tropfrog wrote: That is about the same time as the same species comes out of dormancy in southern Germany. I do Think that this longer grow season is good for my trees.

Problem is, light levels are lower in the north, and the sun is weaker (With relatives near munich, I have been shocked at the difference 800km make). This means your tree will stretch more. And you get weaker growth.