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This session covers how to raise and lower the humidity. How to cool your growing space and how to water when humidity is high and low. Remember that humidity controls the rate at which the medium dries. This means that you must watch the humidity and temperature and water accordingly. Humidity can also be an inducement to rot, so air flow gets factored in to control rot. Sounds like it is getting complicated and the variables continue to mount.
Hallie asked for recommendations on a good humidity measuring device:
Tell Hallie & others: I never owned a humidity measuring device of any kind in my life. I walk in the greenhouse and sniff. If I feel the air on the back of my nose, it is too dry. If the edge of my nose or the rims of my ears tickle, it is too wet. I'm serious - that's how I do it. I will tell you this: I see 99 dry greenhouses for every wet one. People just do not believe how wet a tropical jungle or rainforest can be...EdW
Barbara
My system, per nozzle, is 1/2 gallon per hour, we used a humidistat connected to a Cyclestat (a short range misting timer) to come on whenever the humidity goes below 60%.
Ed
Sounds good. A Monarch M-1 nozzle delivers 0.63 GPH @ about 40 psi and it is pretty dry. It's a blessing to get that kind of delivery at ambient water pressures.
Hallie
In the last couple weeks, ours hasn't gone below 95%.
Lois
Yours and mine too, Hallie - it's always sitting on 90% + With LA humidity, that sand floor and a heavy watering hand!
Ed
Hi, Lois. Got done with the consulting thing just under the wire. Re 60 per cent humidity. Remember a true mist system - like Barbara's - can buffer the humidity. That is, when humidity gets too high, a fine mist will actually lower the relative humidity within an enclosure.
Lois
Didn't know that! Next time you're in Bossier City, will you measure me for a misting system?
Sparky
Gail, you're right about humidity!! My pool had excess water and it hasn't rained in a week!!!
DrJay
That is why I love my Fogger....cooling and humidity control all in one package.
Lois
Or my greenhouse! I'm forever fighting the black sooty mold on dendrobiums and phals.
Barbara
That's correct, the mister will lower the temp. by 5 - 10 degrees within minutes.
Ed
Sorry Lois - we closed that part of the business June 1. MAY have some bits and pieces that would help - we'll talk about it. I'll see you in Little Rock on my way to Salt Lake City. Good grief!
Ed
True - a good mist system will lower temperature but it will also lower relative humidity when that factor is in the upper limits.
Gail
Ed, you're talking about this working in an enclosure. What would it do for my patio, it's screen enclosed and surrounded with lattice. I want to run some sort of a watering system around the edge to water or mist ( whichever would be adequate) my plants so that I don't have to stand out there with the hose for over an hour, each time.
Peter
I am having a mister installed for my unfinished greenhouse. On each wall of greenhouse , I will have mounted phals with tree fern. Should I aim the mister head at the mounted plants or install the mister under bench?
Ed
Perhaps we need to specify that a mist system would never be used to water plants. A mist system is designed to temper the greenhouse environment. A spray system might irrigate, but we would never recommend that in a hobby greenhouse.
Peter
I have step benches in the middle of my greenhouse. I thought that it's bad to mist/water directly on top of the plants.
Ed
Use an impingement nozzle such as the Flora-Mist (it comes in 4 or 8 GPH) to obtain a shaped (round) spray pattern. Planning radius is 6 feet with nozzles spaced every 4 feet. Good coverage and reasonable delivery without flooding the joint.
Evlyn
I had a very horrible experience with a mister. Bought Ann Mann's version, which is definitely not perfected. It went through three motors last summer. Got a calcium deposit from the calcium in local water on all the leaves that I still have not gotten off. Got rid of it and went to a cell-deck, and am much happier with the result.
Hallie
What is a cell deck?
Evlyn
Wet Pad
Ed
Peter, you asked about mist/watering on top of plants. My earlier message re difference should help. When placing mist nozzles, we like to put them right in front of the interior circulating fans. Since most of our greenhouses use some form of horizontal air flow (HAF), that is an easy solution. The idea is to get the moisture into the air, not onto the plants. Always position any potential drip over walkways - people don't mold very easily.
We like cell deck, but disagree with the way it is installed in most smaller greenhouses. We like to shroud it on the inside of the house and blow the air out with a high velocity fan - sort of a super swamp cooler. Then we open the top of the house to let the heat out and we're left with nice cool air at the plant level. Most people put exhaust fans in the opposite wall at plant level and exhaust the best air in the greenhouse just as fast as the fan will turn.
We like a timer/thermostat combination for mist system control. You set the timer for whatever interval seems appropriate to your area and setup, then break the solenoid line with a thermostat. If it is warm when the timer says GO, water flows. On a cloudy day or cool one, the thermostat will say NO and the system stays dry. Beats any humidistat I ever saw.
Cell deck is normally installed on the outside of the greenhouse, flush with the exterior wall. We go inside on the same wall and build a box as wide and high as the cell deck and deep enough to house a big high velocity fan (we get ours from Grainger). We then set the fan to come on at a certain temp, the water in the cell deck 3 degrees higher. The fan blows cool air into the greenhouse displacing the hot air at the top and the 3 degree differential keeps the fan running after the water cuts off to dry out the pads and make them last longer. To top it off, we use soft water (softened with potassium chloride) and our pads don't cake up. A little consan now and then plus 5 gallons of bleed off a day keeps the system trouble free.
Lois
You take 5 gal/day out of the "tank" and replace it with fresh?
Ed
Most any cell deck system will use a lot more than 5 gallons a day to operate. We bore drain holes a bit down from the drain down water level. When the pads shut down, about 5 gals will drain out this overflow into a bucket and we put it on the garden.
Evlyn
If I understand, the fans are directly in front of the cool pad? A good source for fans is Triangle Engineering in Jacksonville, Arkansas. They make all sizes and kinds. Nice people to deal with.
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