What's wrong with my Rowan sapling

[WilbursWinnie]

Advice needed!
Does anyone know what I'm doing wrong with this Rowan ? I got it as part of the Woodland Trust tree giveaway last year.

Its leaves are browning slightly. Am I over watering it?

It's on our window ledge in the kitchen. The room doesn't get hot. Daytime temp of around 16/17 degrees.

Any ideas?

Photo would help!

It might be happier outside. And perhaps in a bigger pot.

We have a corner of our garden where we would like quite a bushy tree also quite tall but that doesn't have huge roots as the there is not too deep ( think height of average sofa ) . Any ideas would be appreciated , photos too if you can . Thanks loads

I read that you should grow in pots for two years before planting out.

Maybe you are right, and I should just plant it out.

I agree, you can't keep it inside.

I don't know why someone would advise to keep it in a pot before planting (but they mean a pot outside) - is it perhaps just so you don't accidentally let it get overtaken by grass? You could solve that by planting it with a wide circle dug around it?