Tree Lupins; in containers or?

My sincere thanks to the kind person who sent me tree lupin seeds last year; I had been aiming to grow one as I had to leave a beauty at a rental!.

I sowed several of them early this year; good germination and some promising young plants. Then today I realised there is a bigger one hiding in a container amid spearmint plants, about 30 inches high and well branched off.

The container is a large old black coal bucket and I am wondering if it is OK to leave the plant there? As you know, this is a very windy place and I have this year had to move a lot of things to save them .

I am delighted! Looks so very vigorous and healthy. Thank you in advance, Oh and I have I think four other smaller plants already out but much less vigorous .