Best greenhouse floor material

[MJMcKinney]

I am building a 14 x 24 greenhouse that will be a lean to attachment on the back of a garage.

I originally planned on pouring a concrete floor with pex tubing poured into the floor for heating purposes.

I have since learned that some feel that gravel - pea sized or larger -would be a better choice than concrete because the greater surface area of the gravel will help with raising humidity levels in the greenhouse.

However I see lots of problems with a gravel floor - maintenance, varmits, etc .

Any advice on the pros or cons of concrete or gravel floors would be greatly appreciated.

Mike