[rowlandwells]

we have several Christmas trees in tubs they have been in tubs some years now and there beginning to look as if they need a pick me up or feed so what in your opinion's would be the best thing to feed Christmas trees maybe they need to be put in larger tubs?

after Christmas there put back in there summer beds I bury the tubs in the ground and water the trees through the summer months so any advise would be welcome

[New shoot]

You are effectively growing them like a bonsai tree so they really need a root prune and maybe a larger tub as well.

I would leave it until after Christmas assuming you are using them for display.  Once out of the tub, you need to carefully untangle the roots and prune out some of the very thick ones or ones that are circling the pot.  Make sure you leave plenty of fine feeding roots in place.  Repot in fresh compost - for a tree like that I would recommend a John Innes soil based one, then make sure you keep them well cared for while they recover.

With fresh compost there is no need to feed straight away, but you could mix some slow release granules into the potting mix.  If you don’t have them, just a basic balanced feed applied a few times next growing season would be fine.