I'm repairing an old green house ( about 20 yrs old) and I was looking
for suggestions on what's best to use on the floor. It's just bare soil
now and from the looks of it has not been used for a spell.

I have found several places where water has leaked in and that's
why I'm having to fix it up. Termites have eaten away at the wood
frame and I imagine they like the damp soil.

I would appreciate any suggestions.

I've heard Malcom Beck say to use organic mulch, probably cedar would be best......

Somewhere else I read where a guy was defending several inches of sawdust as THE ONLY flooring to use. He had reasons to shoot down everyones counter claims for all kinds of expected problems. He was apparently in the greenhouse construction business and claimed that greenhouses with sawdust floors he had installed 30 years ago had many fewer overall problems (disease and pests) than concrete, stone, pebble, creosote wood, or even wood chips. The only problem would be if you were allergic to the wood dust.

For many reasons including availability, smell, tacticle sense, I believe the cedar flake products would be my first choice, followed closely by a gravel of some type (pea or granite). In fact, as I prefer diversity, areas with gravel below planting/watering areas and cedar flake in walking/aisle areas might deliver both aethetics and performance. The gravel would provide for good drainage, and you would only be replacing the cedar in the smaller walking areas. Sawdust would not be on my list. Dusting would seem to be a significant problem as would the uncertainty of the source/treatment of the wood. Insect infestations would also seem a risk.

Shredded cedar is best. And yes, Malcolm Beck will tell you the same.