luckyzl230, you do have the right idea. Getting a solid frame then fill.

Thanks. Maybe it's that time of season where they don't carry the type of pier block I want.
I guess I'll have to go shopping around to find them.

If Lowes and HD done have them try a larger Ace hardware or landscaper that does hardscapes.

You might ask at HD whether you can "order" them and have them delivered to your local HD for no charge.

>> Am I understanding that the base of the greenhouse structure is above ground where cold air can get underneath?

If someone DOES need to do that, one approach would be to enclose the open space with something insulating. That might be expensive, so maybe just insulating the exposed floor would be more practical.

I will ask HD tomorrow about that. Didn't think about Ace but will try them as well. The base will be level with the ground. My plan is to sink the pier block into the ground just covering the concrete portion and then back filling the south side with dirt that has a slight slope to it. In other words the north side is perfect but will still use pier blocks to anchor the 4X4s . I need a total of 8 pier blocks.
I have everything planned in my head but I guess it's hard to describe.