Any gardening experts out there? Our neighbours have erected a large greenhouse at the bottom of our garden. We would like to plant some trees to screen us from this truly ugly structure. We would need to take up some patio slabs to do this so really need trees whose roots will not bring up surrounding slabs. Also the trees will need to reach (or already be 12-14 feet high). They need to be evergreen and very 'bushy'! Have done lots of research but am at a loss (probably too much information!). Many thanks.