probably a stupid question, but depth of soil?

Or to write my question out properly:
Having layered wood plus compostable stuff, how much depth of soil do I need to have?

I moved the wood and compostable stuff into place in october, then had major surgery, and am now starting to cover the beet with soil. The top soil I removed in the first place is nice and naturally fine but with some stones. I want to get it planted and covered with mulch before the couch grass sets in (it's surrounded by the stuff sadly).

I have seen huge nut trees growing in 2 inches of soil ok more like pure bedrock near a cliff.
But if I tried to grow carrot, I would not have anything to dig.

If you are going to harvest root crop, then your soil should have a dept of at 1.5 the storage root

I think a good rule of thumb would be a minimum of six inches, but the more nice soil you can get on there the better (to a point-up to around a foot or so). That being said I have some really shallow areas on my beds (less than 2 inches), and some relatively deep areas (something between 18 and 20 inches). Everything is seeded with a random blend of cover crops and mulched heavily (6-10 inches). So...it depends!

Hi Henry, I'm no beet expert but Google tells me they need a fair amount of nitrogen. The decomposing wood of a new hugelkultur bed tends to suck up some nitrogen from your soil. So you might try throwing in some white or red clover seeds as a cover crop. That could reduce the possibility of grass taking over and also add some nitrogen fixation.

I think that's a grest question.
Im converting a raised bed to hugelkulture ay the moment.
Ive gone a spades depth below the surface, filled that wood. Then i was planning on putting 18 inches of soil and compost on top (2 rows of scaffold boards for the sides).

Before trying hugelkulture, deeper worked better. Now my concern would be too much soil to share the stored water.

Any thoughts? Ty

I don't think you're just dealing with stored water , but also the wicking action from the wood pulling water up from the ground into the bed. With that being said I wouldn't worry to much about having an overabundance of soil in your beds. Keep in mind also that a all of that woody mass Wil convert into soil overtime as well. No need to over think things. I would just build the bed upto the height you're comfortable with, plant, harvest, and enjoy!

Good points Dave thanks. Very easy to over think things.