Jon's pictures in the many threads he has posted in show concrete between the blocks except for the single-block-high ones.

Check out the pics in the thread linked below.

Dave

Here is a link that might be useful: cinder block veggies

I'm not Jon (and unfortunately my veggies don't look like his).

I have a 32' dry-stacked two-block-high blueberry bed. It's only been through one zone 7a winter, but so far hasn't lost structural integrity.

Dave...as usual...nailed it ;-)

Perceptive ;-)

Check out my videos on how I built my beds (and other things no one really cares to know ;-)

Here is a link that might be useful: Building the raised beds...see all nine videos