Hi Jeremy,
You have come to the right place, I fill mine with the same soil that are in my beds...

I do mostly Cinderblock beds, click on the link below and watch all nine (one minute each) videos to show how to do it .

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Here is a link that might be useful: Survey of my garden 3-20-2010

The only problem you would have with freezing is if the perimeter blocks retain water...You can see by this video below,that I took that into account and cut the interior of the block to allow drainage into the bed...
Watch all 9 video's on how to construct a Cinderblock raised bed...

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Here is a link that might be useful: Drainage if Block is Mortared

Thanks for the input John. I watched your videos prior to making this post and have absolutely SALIVATED!! Your block gardens have been my inspiration in this project!

Busting due to groun freezing is less likely, because it is the
excess moistue (water)that can cause volume expanstion. in a well drained soil,
to the block pockets that will not happen.

On the other hand, you have to consider your resources. If quality garden
soil is costly, filling the lower block with that precious materia
is wastefull. So I would rater fill the lower blocks with stones, rocks and cheap soil.

Jon, Are the holes in your blocks all lined up from top to bottom ? So the soil goes all the way through the 3 blocks high ?

Hi Angela,
Yes....By nature of the design...
The Blocks are all 8" x 16" x 8" Tall and when you stack them for strength..you make them interlock by the diaphragm design... Everything lines up and runs into the bed... The largest beds have rebar and pipes (for floating row covers and trellises etc etc..) in the ends and in the middle of the beds..

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