What to do if root ball of conifer too big to be planted at right depth

I would have mound planted them and propped them up with 3 substantial planks of wood. like they do when planting large mature palm trees.
i guess a lot depends on your water table all year round.good luck with them btw.

 

Hi Shiney. Yes, I did, but I'll be staking them as well. Cheers,
laurence

 

Hi Wee Tam,
I did mound them a bit, but the stony clay subsoil seems free-draining as far as i can tell by emptying a bucket of water into the hole.

Hi JWK,
It worries me, too, but the subsoil seems to be free-draining.
I'll upload a photo of the planted trees with this post. Cheers, Laurence