I'm about to dig up an old garden with about 40 to 50 roots of old flowering bushes -- mainly Rhododendrons & Azaleas. The stumps on some of these roots are 6" in diameter. I live in a National Forest, so I should be able to get felled trees, but can I use the old bush roots in the hugelkultur too? There's a planned 5' x 15' plot for a veg garden. I figured I could bury the roots there instead of paying to throw them away. Thanks.