Logs

Can I use old red wood fencing for my hugel kompost?

Sure. Hard to decompose wood (like cedar) is problematic in hugelkultur because you want the decomposition to feed what you plant on top. But you can still throw some cedar logs in a hugelkultur, you just have to make it a minor component and have a good mix of other wood so that there will be a variety of fungal species present. If redwood is what you have to work with, use that. But be sure to add other biomass to it to set a good table for your fungi.

Thanks for the help