We live on Vancouver Island, where most of the trees are douglas fir. We have a good deal of these that have fallen and rotted on the forest soil over the last 100 years since this land has been logged last. I figured that the main reason to not use fir (since it doesn't rot well) is not valid if the wood is already very rotted.
The following picture is at about 70% of the final height of the hugelkultur. I erred very much on the side of taller rather than wider, since I expect to only tend this bed 4 or 5 times per growing season, since it's 50 miles north of my residence on my parents' 3 acres. I am hoping that the well-rotted wood will keep water through the summer months, which get far less rain here than the winter.
I've located the bed in a very wet low lying area, water flows 24/7 here during this part of the year. I dug down 1 foot which essentially created a pond up to ground level instantly. It will be interesting to see what happens to a hugelkultur that has its feet in water 6 months of the year.
Here we are dumping some gray clay on the hugelkultur. We have gray clay (almost blue) by the thousands of tons in this area. I am very much playing this by ear as far as design and materials go. The bed is probably 3 feet wide and 6 feet tall counting the part underground.
The tractor pictured here sunk into the mud all the way to the tops of the front wheels, since it is so wet here. We spent an hour digging it out and did not use it for the rest of the day.
Above is the completed hugelkultur bed. I layered with everything on the property I could get my hands on, in the following order: bluegray clay, a little sand, brown mud, charcoal from a burn pile (20% terra cotta from all the clay here), heavy chickenshit strawcompost, paper feedsacks, dry straw from the property, more chickenshit straw mat, more dry straw, logs to keep the straw from blowing.
In the above picture, you can see the pool of muddy water from where we had to dig the tractor out. I'm leaving the pond there for now.
The chickens are always very excited when earth is being moved or torn up.
I hope to update this post in this thread as progress continues. I plan to grow indeterminant sauce tomatoes and possibly basil here.