I've already talked about this bed in the first plant combinations photo I posted. 4x6 timbers created a 10x13 foot border around the existing Silver Maple tree. The area inside the border had been backfilled with a decent weed-free sandy loam topsoil. I was told this had been done almost ten years prior to my moving in... and it had obviously not hurt the development of the tree. That first year I dug several test holes in the bed and, even knowing Silver Maples, was astonished at the complex root system just beneath the surface of the soil.
The myth and the reality combined to keep me away from this bed for two years. You can read a bit more about it in Plant Combination # 10884.
I'm glad I got past that, however, because the plants have grown and spread and this old bed is a real pleasure to garden in... particularly this spring.
By the way, hoping this is appropriate, I bought some [to me] very unique Hostas from Sebright Gardens in Brooks, Oregon and I want to highly recommend them to you.
The plants I received had excellent root system and several buds and have already developed into attractive specimens.