Hole depth vs. hill height

I've been reading and searching. I've found tons of useful info, but not exactly answering this particular question.

I have heavy clay soil, and wanted to build up hills with holes beneath. I plan on mixing my local soil with topsoil and black cow manure. I don't know if I should do an even 3 part mix, or half local soil and 1/4 topsiol, 1/4 manure. I'm also going to lay some wood ash on top, and then a healthy mulch layer. So, my first question would be which of the two mixes mentioned above would be better.

And now my main concern. How deep a hole chould I dig vs. how high a hill I should build. I plan to use the leftover straight local clay I dig up to build a dam uphill of each hill to avoid washing out in heavy rain, which happens frequently with late spring and summer t-storms. My local clay just doesn't absorb all that much and runoff is a potentially huge problem. Which is also why I want to build hills, to keep the crowns above that possible saturation level.

Any advice would be greatly appreciated, as my 9 rizomes came in today, and they go into the ground this Sunday. It's going to be a digging, mixing, BBQ and homebrew extravaganza, and if anyone local is interested in coming by, PM me!

Use the even mix and skip the mulch. A foot total (hole & hill) is plenty. Mulching is an invitation to molds & mildews.

I wouldn't do the "holes below" based on personal experience (albeit a little modified.

Here's what happened to me;

My first year I dug 2 foot deep holes for 6 rhisomes. I also have a heavy clay soil, the red oklahoma crap. I placed bottomless containers in them to control the outspread and filled the holes with potting soil (miracle grow moisture control).

I placed the new rhisomes within 3 inches from the soil surface.

All seemed well and the plants did thrive and were joyous. And then the rains came.

The holes, logically but unknowingly, filled with water and bogged the new plants. The effects showed themselves as nutrient deficiencies (sensibly as the root were shutting down due to lack of oxygen) and I chase the apparent problem for a couple months. Plants slowly died before I talked to a Master Grower that suggested that I had bogged them in. After digging trenches away from the holes I realized the MG was correct and I proceed to manually dip water out of the trenches daily to allow the rhisome (that survived) to recoupe.

The end result was a loss of half of my cherished plants.

Till a plot, double dig, make a raised bed, whatever but DONT DIG THE HOLES IN CLAY.

The rains we had were freakish and non-customary for the area and resulted in a devastation of my garden.

Bogging as a result of digging holes in clay makes sense. I'll go with the hills then.

It sounds like it also wouldn't hurt to dig a ditch for drainage downhill, and place the clay uphill to prevent the hills from washing out.

I'm planting 3 each of 3 different varieties. I'm figuring a row of each, spacing the like varieties 5' apart to allow for root growth below the hills, and a good 15' seperation between varieties.

I plan on letting them grow up 6' and then training them horizontally for another 10'-12'. I know that that adds extra work, and will lessen yield. I'm trying to keep my total cost of the setup down, and keep my feet on the ground. I could always do vertical trellising in future seasons.

Thanks for the replies!