Since the floor is only a very minor source of heat loss in a greenhouse during the winter, your concerns should be toward good drainage and something to help raise humidity in the summer. Crushed gravel, 1/2 to 1 inch, works well. Rubber mats would not hold any water to improve humidity. Wood chips would help with humidity, but as you mention, would probably rot rather quickly in a greenhouse environment.

Blooming Bulbs has Alfresco for ~$5/bulb for fall delivery. Don't remember the others right now. They had a lot marked as sold out, but I'm GUESSING they are in the process of updating their site. Don't recall the other that had "the usual" stuff...might have been the goofy site in GA. Just scooting around the web looking. Didn't see full offerings, but BB did have Alfresco, which was on lots of wish lists. Will keep those that care posted. K

I'm in North Central Iowa and I had some nasty brown patch 3 years ago. I over fertilized my lawn for several years with the Scott's 4 step plan. I stopped it cold turkey and now use Milorganite and/or alfalfa pellets. Even though I live a half mile from a huge Cargill soybean processing plant...soybean meal is not available at retail here in my small town. I could buy a train load from Cargill but, not a 50# bag. (sigh) So, I use alfalfa pellets. They work well in my garden and flower beds too. I used some corn meal I purchased from a Wal*Mart food store in 5 lb bags on my fungus. I applied about 20#s per 1000 sqft just on the affected areas. I made 2 applications about 30 days apart and I bagged the grass in the fungus part of the lawn for the duration. The lawn recovered fairly fast once I put the corn meal on and stopped adding too much synthetic fertilizer. The next growing season I used some cracked corn on the area that had the fungus as I could buy it locally. I had a lot of happy birds but no more brown patch. You can buy a hand de-thatching rake at most Menard's or Lowe's. I have one and have use it now and then to take care of some areas of my KBG that seem to accumulate some thatch. It's a chore to use but, it will not tear up your turf like a power de-thatcher. It will also allow you to rake the brown areas of your lawn to remove the dead grass for over seeding.

I have a fake Hawk that worked for a few weeks but the birds smartened up and don't fall for it anymore. Now I have to put bird netting, which i picked up at Armstrong Nurseries for $10. I also use long strips of aluminum foil tied to the netting and this has worked for me so far. Just be sure the aluminum doesn't touch your plants. You may consider planting some cat nip to attract more cats. Nice looking Longan, what variety is that?