I did it wrong. How can I fix it?

TL;DR

Lesson learned. I fell for the temptation to combine two permaculture tools (Hugelkultur beds and swales) into one for double the benefit. Thankfully, I realized my mistake before the point of no return.

Longer version

I hand dug two "Hugelswales" before watching Paul's 3hr+ Hugelkultur lecture on YouTube and realized I'd made a mistake. I'm in Minnesota Zone 4b. My backyard slopes south towards my house. The soil is very sandy, and we live ~400ft. from a river. Lots of oaks, basswood, cottonwood, buckthorn, and maple trees. The yard itself is just lawn with some trees and a circular little flower bed.

The question
What should I do with the area instead? Will the “frost pocket” problem hurt too much, seeing as I’m in MN? I'll have to do more digging, but I'm thinking... perhaps a sun scoop Hugel? I don't know. This is my first garden. I've been around permaculture people a lot ~15 years ago and I've been reading/dreaming about it for a long time, but this is the first opportunity I have where I have access to plenty of resources, have the land, time, and energy.

Oh, and does it matter if hugels are built level or not? Trying to make them level was one of the reasons I originally dug the trenches on contour...

I don't see how this would be a problem. If you had more slope there might be a problem with washing out, but that yard looks flat enough. I'd fill those suckers up with wood to at least two feet above ground level and cover that with the dirt you've dug out and you'll be good to go. They will sink over time but you'll be left with some great soil in a low mound. I dug my hugles into the ground and they work just fine.  

Matt Todd wrote:I don't see how this would be a problem. If you had more slope there might be a problem with washing out, but that yard looks flat enough. I'd fill those suckers up with wood to at least two feet above ground level and cover that with the dirt you've dug out and you'll be good to go. They will sink over time but you'll be left with some great soil in a low mound. I dug my hugles into the ground and they work just fine.  

Nice! Thanks for the quick reply. How about the “frost pocket” problem? I’m in Minnesota where growing season is already short, and was hoping my Hugels could help (not hurt) that!

Matthew LeVan wrote:
Nice! Thanks for the quick reply. How about the “frost pocket” problem? I’m in Minnesota where growing season is already short, and was hoping my Hugels could help (not hurt) that!

If you overfill the trenches with wood and cover that with soil, you'd have hugle mounds rather than a depression that would "attract" frost.

Or maybe you're worried about the space between the two rows collecting frost? With open ends I don't see that being an issue.

Soooo... the piles of dirt in the picture, are just the dirt from the ditches?

My understanding is that one way to build hugels (the recommended way overall from my interpretation) is that you put the punky wood on the ground, then you dig the ditch dumping the dirt and packing it around the punky wood to get the height of the hugel. The ditch then stays empty or gets some mulch in it.

Wood floats - so burying wood in a ditch in many ecosystems is considered a bad idea (there are even some horror stories but that was were slopes were involved.) I have buried small bits (firewood sized chunks max) in unconnected spots around trees which seems to help the summer drought issues, but they do not remotely qualify as a hugel.

I hope some of the people from Wheaton Labs will have a look.

Possible fix: My gut feeling is to bucket up one section of the dirt, put your punky wood where that section of dirt was laying, shovel the dirt that's closest on top of and packed around the punky wood. Now you've got a spot to put the next wood down. Work along until you get to the last bit where you use your buckets of dirt for cover. Does that make sense?