Will blue tit chicks get out of the deep amphora they have nested in, if not what can I do?

I have a decorative amphora in the garden held vertically on a stand. I was surprised to find that we have blue tits nesting in it and from the racket they make when mum turns up it is is a full brood. I'm just a little concerned though about how they can get out when fully fledged. There is no way to climb out as it is too deep and indeed it is beyond vertical. The adult birds clearly have no problems flying vertically out but will the kids be able to manage it as their first flight? It looks like this basically and is about 2 foot tall. www.britishmuseum.org/.../1613330300