Stopping tree root growth

I was wondering if there is some way I could stop root growth from a large maple tree nearby from entering my raised beds? Something I could put underneath?

Originally there was some plastic underneath but the roots just grew right through it. I'm planning on putting in a rock garden and root growth would destroy it.

Thanks.

 

Use a vertical barrier like bamboo root barrier instead of a horizontal one.

 

www.deeproot.com has root barriers that will work for you.