Building a bed around some trees

I want to build a flower bed against a fence and there are some trees in the area that i want to build in but i dont want to remove the trees. How high could the bed sit without harming the trees? I want to raise it to the hight of the other beds in the yard which is around 2 feet. would this kill the tree?<br>thanks for the help<br>Dingo

 

Yes, the tree roots will suffocate and the trees will eventually die. Its best to leave the soil level at its original level around the trees, out to the drip line.

 

I've seen some diagrams of a way to build that bed and minimize the affect on the tree, which involves large amounts of perf PVC filled with crushed stone radiating from the tree - looks very complicated and expensive - not worth the effort when you might still kill the tree.