I have newer growed lavender before, but the one of them are very tall and not so bushy, should i pinch it/them? Or will they "bush" on their own?

Also when will they be big and strong enought to be planted outside? (The authumn is soon)

I have not had to pinch seedlings they usually branch by them selves.
as for planting out , It would help to know your location/ zone.

gardengus said:I have not had to pinch seedlings they usually branch by them selves.
as for planting out , It would help to know your location/ zone.

Ok, i live in denmark

Had to look that up
and I was surprised we have a planting calendar right here on NGA

Looks like you have the same frost freeze date as I do Oct 10th but your winter is not as cold .
Your plants should do well out side , I would plant them by September 10th to give them time to get established .
The only time I have problem with lavender is when our winter is too wet so a dry sunny location would be best .
I often suggest to people to plant under the house overhang where not much rain hits if they are having trouble keeping lavender.

Having said all that I forgot to ask what type lavender you have?
Not all lavender is hardy (winter strong)