really tall hugelkulture

Hi - my first post here. somehow all google roads keep pointing to this site, so figured i'd give my question a shot.

Anyone see objections to a 4 to 8 foot hugelkulture mound, with most of the height made of hardwood brush?  My goal would be brush decomposition (not so much garden cultivation on top of it); a few cubic yards of black gold years hence would a-ok too.  

not sure if there is an upper limit to brush height  / height between ground & humus layer for the initial magic to happen.  there's be some limbs up to 6" diameter, but since most would be brush smaller than that, I assume the pile would drop somewhat quickly...if initial height doesn't forestall that.

Can't see why not maybe plant it in a legume for nitrogen fixation to help with the decomposition.
Also id make some mushroom slureys. This could be a good way of growing mushrooms from brush instead of bigger logs.

Hi Josh, welcome to permies!

Your plan sounds excellent. I like Rob's tips too. You might find that garden cultivation becomes attractive in a few years as a big hugelkultur bed can drastically reduce the need for irrigation.

Here's a thread about a 12 foot tall hugelkultur bed at wheaton labs:

https://permies.com/t/36537/permaculture-projects/giant-hugelkultur-feet-tall-basecamp

There is a general rule that in fire prone areas you don't make wood chip piles deeper than like 8" because the heat of the composting plus the combustability of the wood can lead to spontaneous combustion.  That'd be my only concern- combustability. If it's all filled and covered with dirt,  I don't think that's a problem though.

Hi Shawn, thanks!  And great thread about those 12' beds, that is just hilarious.

These brush piles are a ways off from the main garden, but I'm definitely considering hugelkultur for future beds.  As always, it's fun to just see what happens.

Cheers.

Might as well throw a few seeds on there and see what happens.

Good luck and let us know how it goes! (We love pictures!)