Steve B wrote:

I think a lot depends on if your wall is subject to lateral
loading (like a free-standing wall) with no right-angle bends
in it, or if this is soil retaining wall.

What I have seen done a lot on 6' high walls is spacing rebar about
4' apart. Screens are put into the proper places within the mortar
so that grout does not flow out,

I think what you mean by "screens" is this:

http://www.barker.com/products/index...31&product=311

This seems to be referred to as "block ladder mesh" and is meant to give
tensile strength to the mortar layer to allow for more flexing and less
cracking. That mesh wire looks like a ladder, but others have a diamond
pattern:

http://image.made-in-china.com/2f0j0...Block-Mesh.jpg

My wall will take a lot of freeze/thaw cycles, and we have blowing
sand that may keep the base wet all winter from the rain and snow.

I don't quite understand how blowing sand plays a role in water
exposure, but what-ever...

Also, it will be setting (sitting?) on blowsand, and tending to
settle, so horizontal rebar, even for a three to six course high
decorative pony wall.

I don't know what this blowsand is. Is this on a beach, or a dune?

It's a whole lot easier than trying to straighten or jack up a
sagging wall.

So this is a non structural, decorative garden wall, at most 5 ft high.

You don't say what you plan as a foundation.

I suggest at minimum you dig and pour a concrete foundation at grade
level, anywhere from 8" x 6" to 12" x 12" (and include a healthy amount
of rebar) to give these blocks a good base.