Hugelkultur and Allelopathy

After coming across the concept of hugelkultur, getting excited, researching it, and drawing up my gameplan I have found that there are a few things left unanswered for me. Mainly the relationship between the use of apparently allelopathic trees and the fertility of a hugelbed. I know not to use the cedar on my property, but the bulk of what i have to use is coniferous(lodgepole, ponderosa, douglas fir, western white pine, mountain hemlock, western larch, englemann spruce) and paper birch being my only hardwood. The birch is my top choice, I have lots of rotted pieces around. I also have an abundance of rotting logs on the forest floor, freshly fallen trees, and lots of slash piles from the last few years collected by the previous owner. Basically I am just trying to fine tune the building of my hugel beds, and I don't want to screw them up by adding too much of the wrong thing.....

My questions are:
-Are all conifers allelopathic? I was not able to find any scientific or research references on the topic, just mentions on blogs, howto's, forums, etc...

-Which parts of a conifer contain the most allelopathic compounds?

-How long before these compounds break down? Does the quality of your "micro-herd" effect the breakdown speed?

-What about green needled fresh limbs, helping or harming the cause?

-What about building a hugel bed over unpulled stumps, basically incorporating them into the bed. Any problems with this?(No risk of resprouting with the conifers i believe)


Anyone with any experience or knowledge regarding these issues please speak up, I would really appreciate it!

myself I would just go about and gather up all the downed logs and use those..but if you have nurse logs that are already supporting life in the woods, leave those ones..

I'd start with the birch and then use them up first.

see how they do on your property..maybe make one bed of the conifers and see what happens when you plant on that..it can be a small one.


I would avoid things that are obviously alleopathic like walnuts

I've been using juniper in my buried wood beds, but I put it on the bottom, using elm and oak, preferably rotten, as the top wood layer. Most of the juniper I've used has sat out in the weather for at least one year after being cut.

Did you see this thread? https://permies.com/t/12206/permaculture/Hugelkultur-Good-wood-Bad-wood

There's a nice discussion about it over there. Dale is trying to pull a bunch of this info together for a good reference spot.

I would think, though, that any wood that is to the point that it's rotting should be ok to use in a hugelkultur bed. If you think about it, The whole point is to get it to rot/compost, so that old wood is already on its way.