I thought some people here might find this interesting reading. This was on yesterday's ICPS list serve, and I know everyone doesn't belong to the PFT forums and there.
There were several posts to this question, besides the one below. One was as simple as a dorm room fridge(with door removed) and ultrasonic humidifer in a growchamber(somebody actually did this). I thought of that before, lol, but never heard of an actual occurance.
Date: Mon, 31 Jan 2005 09:10:41 -0600
From: "Patrick O'Brien"
Subject: [CP] highland tanks, etc.
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I've come up with my own solution for this problem. Everyone's situation and preferences are different, so variations of this can be successful.... All of my growing is done indoors, in both the basement and upstairs. I grow only Nepenthes, but the rare highlanders need special conditions to grow properly, just like darlingtonia. All the highlanders are grown in the basement, but even there it can get pretty hot in the summer with all the flourescent fixtures going. You need to first decide how big of an area you want to grow in. You can grow a surprisingly large number of plants in a relatively small area. To create a very cool to almost cold environment, while being extremely humid at the same time, I use an ultrasonic fogger. I'm not going to get into where these can be bought, as they vary too much in design, price, and source. A Google search will lead you in the right direction. The type of ultrasonic fogger I use is designed for agricultural applications (many creative uses here), and is from Green Air products. Yes, they are expensive. The only time I have to adjust the temperature in the basement, is summer. Build the actual enclosure that the plants will be grown in. A size I'll throw out here is 4x4 feet. Build it with four supports (the corners) so that the floor of the enclosure is at least around 3 feet off the floor (more on why later). The frame of the enclosure can be made of wood (use exterior-grade paint if you use wood) or PVC pipe. Make the plant-growing area itself, which is supported by your corner supports, around 3 to 4 feet high. Basements vary in depth, so measure appropriately. You have to leave enough room between the top of the growing chamber and the ceiling for your lighting (flourescent fixtures, etc.). Never have your lighting closer than around 5 inches from the ceiling, no matter how cool you think your lights may be. Enclose the plant-growing area with clear, translucent, or white plastic sheeting, styrofoam sheeting, vinyl sheeting, hard acrylic sheeting, polycarbonate, fiberglass -- whatever. Seal it well so it is fairly airtight. The top of the chamber should be real glass, ABOVE which should be your lighting -- not inside. Now, here is why the plant-growing area is elevated around 3 feet or more off the floor....This is a large expense again, but only if you need it -- Buy a portable, free-standing air conditioner (they look alot like a dehumidifier). Get a good one in which its air is exchanged through a hose, with the air outside the house (through an opening like a dryer vent, or customized vent). Place the air conditioner under the growing chamber. The ultrasonic fogger is also under the growing chamber, but away from the air conditioner. Have the water reservoir that gravity-feeds the ultrasonic fogger, placed on whatever side of the growing chamber you want, as long as the water line from the reservoir to the fogger isn't too long, and doesn't kink. The fog is introduced to the inside of the grow-chamber through a hose. Now, here is the unusual part that makes this effective, and the air conditioner hardly has to run at all.....Build a second enclosure around 2 feet or so around the entire plant-growing structure you just built. This is the airspace that is cooled to your desired temperature, WITHOUT affecting the humidity inside the plant growing chamber. Leave some sort of an entrance, be it a doorway or simply a large panel that can be slipped in and out of place, for you to care for your setup. Try to use an insulating material for this secondary enclosure. A good one, that is fairly priced, is styrofoam sheeting. This will maintain an internal temperature for your plants, and I have found that even though there are enough plants growing in the chamber by themselves to maintain the humidity, the ultrasonic fogger's water supply is extremely cooled because it is in the setup as well, so the plants are getting a misty-mountain effect. If you know what a wind-chill factor feels like for us humans, relate that feeling to cool-loving plants here. Another key to this whole setup, is to use a separate controller for both the ultrasonic fogger, and the air conditioner. Green Air Products manufactures the perfect controllers for appliances such as these -- cycle regulators for the foggers, and temperature regulators for your air conditioner. You will have to experiment with the timing (cycling) of the fogger, because you want the cold humidity that the plants crave, but you don't want to get to the point of condensation. You regulate this with a COMBINATION of both adjusting your cycle timer, AND using a variable-size vent to the outside of the plant growing chamber. You need a variable vent size because you will need to experiment with how wide of an opening that is needed to ventilate the chamber to prevent condensation, yet maintain a high humidity level until the fogger cycles on again. My vent is around 2 and one half inches wide, by something like 2 feet high. Enough fog and humidity escapes before the fogger comes on again, while the humidity is still high. You may vent this fog in two different ways. If you vent it only into the cool airspace of the secondary enclosure, you need to make sure that you don't have anything in this airspace that can be harmed by excess humidity, such as bare wood. Although venting into this airspace is ok, it is indeed better to vent all the way through to the outside room. This is not enough humidity to harm anything in the full-size room that your grow-structure is in. Just make a vent somewhere in the secondary (external) structure, the same as you would for venting into just the internal, cooled airspace. The air conditioner will probably run a little more, because the whole-room air can get inside the grow structure, but not quickly enough to trigger the air conditioner on too much. Again, if your setup is in a basement, all the better. I personally vent into the internally cooled airspace, so the air conditioner hardly runs. The highland Nepenthes are the healthiest, deepest green I've ever seen. They are slow-growing, but that is characteristic of many of them. But the pitchers are richly colored and very tough. That cold fog is what they love. Protect any controllers, electrical areas, and other susceptible objects from water sources. The level of humidity that you are venting should not be enough to cause ANY problems, if you have your setup configured properly. My fogger runs for around 35 seconds, shuts off for around 7 minutes, then cycles on again at the same, constant rate, day and night. I've gotten those extremely small, barely-visible tissure-cultured plants from suppliers (the ones that normally die because they're just too small to survive a normal setup), to thrive in this very cool, humid environment. One last thing....The plants and their pots sit on PVC coated poultry netting, suspended by cabling attached to turnbuckles above the floor of the (internal)grow chamber, so that any excess water drains away from the pots. I periodically soak up the water that collects below the plant suspension. Make the floor area of your chamber waterproof for this, or make a sloping floor with a drain at the end. The floor CAN even be made of plastic sheeting, sloped so the water runs to one end. I don't need a traditional, sturdy floor, because the plants are suspended it about 11 inches on that PVC-coated poultry netting. Excellent fog and air circlation occurs.