I had not heard of Hugelkultur before, I had to look it up. It's an interesting concept. I would think it would take a long time for the wood to decompose, but what fertile soil it would make.
In 2011, I made 2 beds, each 6 x 25 ft with biodegradable landscape fabric on top of the grass, with soil conditioner, top soil and composted manure. I made a 3rd bed this spring 4 x 50 feet the same way on April 23rd.
I planted herbaceous and Itoh peonies in the 1st 2 beds as soon as I made them, and they have done fine. The 3rd bed made this spring had roses planted in it, and they are also doing fine. I added some Brugs to the new bed today, and I noticed the biodegradable landscape paper had already dissolved, and the grass underneath dead.
I already have 3 tree and 2 Itoh peonies to plant in this new bed this fall, and I've ordered 3 more tree peonies and several herbaceous peonies for this area as well.
The beds from 2011 also have bearded irises, lilies, and an edge of daylilies
The new spring 2014 bed today, with roses, and the Brugs I planted this morning.