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

Hi everyone,
Today I had several root balled 7' long Thuja smaragd trees delivered.
My newly created garden has about 12" of brought-in soil over the original clay subsoil. The root ball is huge, perhaps about 18" inches in depth, so you can see my problem. The root ball is held in by a hessian sack tied with wire.
When I removed it from one of the trees, a lot of loose soil fell away to leave the actual tree roots, with some soil clinging to them.
I could plant that tree at the right depth. But when I consulted the nursery website, they warned against removing the hessian, as it would invalidate the guarantee.
I do not now know what to do.
I could leave the root ball intact and deepen the hole by digging into the clay subsoil.
I could leave it intact but dig down only as far as the subsoil, so that the root ball would be sitting partly above soil level, in which case I would have to mound it.
I could do to all the trees what I did to the one, removing the hessian and letting all the loose soil fall away, then planting the tree at the right depth.
I'd appreciate any advice.
Thanks
Laurence

 

Hi JWK. Thanks for your reply. I don't think the clay gets waterlogged. I just wonder if there is any harm in cutting the hessian and letting the loose soil fall away. Thanks again.

 

My garden is more or less surrounded by about 3 or 4 hundred Thuja, all of which I have personally planted. From that experience, my thoughts.

If you have the possibility of returning them, do so. Exchange them for smaller ones if you can, max height 1 to 1,2 metres. Not only do they have smaller root balls, they are also usually cheaper. Added to that, they will establish quicker. I found out that they will easily get to the height you eventually want just as quick as the taller ones you have. In one of the first batches I planted, some were 2 metres tall, but most were only 1. They all got to 3 metres in height by the same time.

However, if you cant send them back. If you are planting them as a hedge, dig a trench at least twice the depth of the root ball, and the width at least twice, but preferably three times the diameter. As has been stated by @JWK fill the bottom of this with organic matter. For hedges though, in my opinion, thuja occidentalis "brabant" is better.

"Smaragd" tends to be preferable for what I would term a more spaced planting. If that is what you are doing, then the hole should still be twice as deep, and as above two or three times the diameter.

Most of the ones I buy are potted, but whenever they are in hessian bags, I have always removed them. If the nursery says that they should not be removed, then obviously you shouldnt. Remove the wire(s) though.

 

Thanks JWK. The soil is completely separate from the roots once I cut away the hessian.I'm still undecided. There are ten of them and they came to £900. Thanks again.

 

Thanks Sandy Ground. The Thuga will be spaced out each side of flights of steps and paths connecting the terraces I've built on a very steep slope. The supplier, Paramount Plants, who sent me ten trees in very good condition, by the way, could just be covering themselves in case there's any comeback if the hessian is removed.

I can't send them back, or rather it would be very awkward, just because they are so heavy. It took two of us using a wheel barrow to get them up the steps to where they will be planted.
I wish now that I had ordered smaller ones.

But I have a question: you say that smaller ones would have been better and would have grown quickly. I agree, but the problem with the soil being just 12" deep in some places, wouldn't that eventually be a problem even with smaller trees once they grew to a certain height?
Or are you saying that they would have time to adapt to the conditions?

What I'm thinking is that the actual root material, if the hessian is removed and the loose soil discarded, is the right size for me to plant the tree with the crown at ground level. I'm still not sure why I should not do that. Or, rather, I'm not sure what harm it could do, given that the loose soil in the hessian bag is not really doing anything, apart from acting as ballast, which is a different matter.
Thanks again,
Laurence

 

Fully agree with that. That price is horrendous even by our standards, so dont risk a failure.

The holes would be smaller, of course, as the root balls are smaller. They would still have to be double the depth though, so things would be fine.

 

Thanks Sandy Ground, and all who have given me the help I needed. I'm doing as advised: digging a deep wide hole that goes down into the clay, then filling it with soil( with added manure) back up to the right level for planting the tree. I've removed the hessian, by the way, and it was only the first tree that had lots of loose soil in the hessian bag.Tomorrow, when we finish planting, I'll upload a photo.
PS: not £900. I forgot the 25% discount for bulk buys of ten trees.

 

Did you manage to get them all dug in and settled?

 

Hi 'M'. Yes I did. I'll upload the photo tomorrow. Rather than break up the subsoil I removed enough of it to create a hole twice as deep as the root ball; then I filled it in with rich soil up to the right level for the tree to be planted. I made the hole about 2'x2.5' wide, so I hope it works. My problem now is that I live high up in the South Wales hills, where winter gales can be quite impressive. I think I'll start another thread in order to get advice about staking. Cheers,
Laurence