Setting up a custom greenhouse

[jmmehler]

So one of the newest members of our society, had a custom green house built (before she joined our society). While the builders had no formal experience with greenhouses, she lives just around the corner from me, and has asked me for help in establishing it, and indoctrinating her in the world of orchids. I hope to share some of those experiences, and will be looking for substantive input from y’all (as we say here in Alabama). Not to sound anti-social, but please, only advice and opinions. No feel-good attaboys.

The green house, 7 x 14 ft, with a slanted roof that goes from about 6.5 ft to 8 is covered in clear vinyl plastic, with a clear corrugated plastic roof. The vinyl offers some drawbacks and some interesting advantages. One day, in the middle of winter, it was 35 degrees outside and 91 in the greenhouse. That was before the electric venting fan was installed on the North side (wrong end) with a passive louvered vent on the south side. Great 12’ fan. Quite, and moves 932 cfm.

She has two electric feeds, one 240, one 120 volt. We ordered a 240v electric heater which works fine. I looked into covering the whole thing in polycarbonate panels, and while it would be a great project, and I’d love to oversee it, I stopped, once the price tag on the supplies alone, reached $1,800. I’d rather focus on getting her money’s worth out of what she already has.

The vinyl used is just a little thicker than the thickest plastic drop cloth, a falling branch, can tear through it with no trouble. In fact it already has happened, and I repaired it with vinyl tape.

To deal with the direct sunlight, I ordered and installed a 7 x 14 aluminet 50% shade cloth for the roof, and a 7 x 11 aluminet 50% shade cloth, that I installed on the west side. Amazing product. Between, these, and the vent, it cools things down pretty nicely.

So now, for the first two subjects
1) I have received samples of 20 gauge and 30 gauge vinyl. The former cost $5.90 a yard, the latter $9.90, and I’d need about 18 yards. Both seem almost bullet proof.
a. Which would you recommend?
b. The old vinyl was stapled on from the outside, and half inch strips nailed over it. Should we pry off the strips, and replace it with new, or should we staple the new to the strips, creating a ½ gap, and then install strips over that?

2) For when the outside temps start reaching the 100s, the most common option is a swamp cooler. This is a 100 sq ft greenhouse. Found one for $298 (there are cheaper ones) that will cool 600 sq ft. it’s advantage is that you can hook it up to a water supply so that you do not have to fill it every day. For just $100 I could buy a 5000 or 6000 BTU window air conditioner. We have plenty of moisture in our Alabama air, and the floor is several inches of crushed rock, which can be watered daily. Which would you choose, swamp cooler or air conditioner, and why?