Watering Question

[Anton]

Well, it has FINALLY come. I am in the planning stages of designing a combination hothouse / greenhouse for my orchids.

She who must be obeyed, doesn't like the look of commercially made units which are available, so I have to plan one that may as well have feng shui !

I have read here on the forum that several people have misting systems hich sound fine to me, BUT ! Do you use these systems when the orchids are flowering ?

Rain drops can cause havock to petals, so I just wondered at what stage do you use these systems, and do they affect the petals on flowering plants ?

I am planning a house in the vacinity of 10' X 12' or if space allows 12' X 14'
so, any suggestions appreciated.

[nertel]

Hi! I am definitely not an expert but I have many of my orchids hanging outside in trees and this time of year they get rained on almost every day. The flowers don't mind the rain at all. They love it! In fact, I had to run out in the pouring rain and grab one that I wanted to take to a show last week and it won a second place. It may depend on the particular type of orchid but I don't think misting them could hurt the blooms. Hope this helps, I'm sure the experts can advise you further.

[Cynthia, Prescott, AZ]

The hard part about humidity systems is getting the moisture into the air without letting the calcium salts collect on the plants. I started years ago by putting a very fine mister in front of a fan. All of the mounted plants down stream from the mister started to lose roots to the salt collecting on them. Had to discontinue the mister. Many people put misters under the benches facing down so that the water just lands on the floor of the GH (greenhouse). This is fine until your GH gets crowed and you need to use that space, or you want to grow lots of cool requirement plants, and that is where it is coolest. An evaporative cooler is a must and adds humidity to a GH, unless you have such high humidity that it won't work very well, then just a great deal of ventilation is used. Be prepared to expect a tremendous amount of energy going into any GH from the sun shinning on it, and that includes the fact that you will be using 50 to 60% shade cloth on the house. I think areas that have very high humidity don't have such intense light as those of us that live in the arid south west of the United States. I am currently using RO (reverse osmosis) water in my humidity system, one small fogger, and hand misting every day. I am trying to get a super fine misting system set up, with misters from http://www.cloudtops.com/ . But this is only practical with RO water. All of my automatic misting is done with a humidistat. Cynthia

[Anton]

Thanks everyone, that gives me a start.

Here in Adeliade, South Australia, it is not uncommon in summer to have "tripe heatwaves". That is, 3 weeks in a row where the temperature does not go below 38C (100.4F) with maximum temperatures easily hovering around the 40C (104F) to 45C (113F) mark with overnight temps hovering around 30C (86F) to 35C (95F)!

A couple of years ago we went 2 weeks in the 40C to 45C (day temps)region and the following 3 weeks 30C to 43C.

Humidity all year round is between 20 to 40%, and very rarely up to 60%.

I got so hot, I nearly had to take my sweatshirt off. ;^)

Hopefully we won't go throught that again for a while.

[Cynthia, Prescott, AZ]

With your humidity, an evaporative cooler will work very well. There are sites on the internet that can give you a formula for sizing the unit. Try to find one that calculates the size based on volume, not floor area. One for greenhouse growers should do it the right way. When you use an evaporative cooler, you will need a minimum vent area. Again, look for the formula for that calculation. I have always used a heat motor vent opener (no electricity), to make sure that the vents are open well before the cooler comes on. I prefer a two speed cooler, and buy a two stage thermostat to run it.

You will also need plenty of fan power in you GH, to keep the plants healthy. Lots of air movement results in rapid drying of the leaves every time you mist and water. This allows you to water/mist later in the day than you other wise would because the leaves must be dry before the temp starts to fall, or you will have fungal/rot problems. I once had a speaker who claimed that you could water any time of day just so long as the temperature did not go below 60F (16C). Since I maintain my GH at 62F at bench level, I started misting very late in the day. I quickly found black spots developing on everything, and bacterial rot on a few things. I finally figured out the reason for our difference in experiences. The gentleman who claimed 60F was OK, grew all his plants outdoors in coastal California. These plants were hardened to go quite a bit lower than 60F. So, when he watered at 60F, he was watering at a relatively high temperature for these plants. In my GH, these plants never go below 60, so I was watering at there lowest temperature. In nature, when it rains (or snows), it never does so at the lowest temperature for the area, as the conversion of water vapor to rain is a phase chage that liberates heat. So, the temp falls to the dew point, BUT, goes no lower. I have seen this many times where snow is concerned. In winter, we can have a temperature as low as 13F, but when it snows, I relax because experience has shown that it never goes more than a degree or two below freezing, 32F.

Be prepared, the cost of the greenhouse will go quite a bit higher than the cost of the structure. Cooler, heater, thermostats, humidistat, vent openners, fans, fogger/humidity system, and a ton of electrical hardware. I just put in a water proof four outlet box for my many little fans (only $4 a piece on closeout), and spent $35 to $40 for the parts and a couple of hours work assembling it. I think I have five of these water proof boxes in there already with another one to go, and this is only a small (8' X 12') temporary greenhouse.

Oh, and it is great to put in an overhead watering system and automate that too. Cynthia

PS. Make your greenhouse tall, with eves at least as high as the top of your door, or higher.

[Anton]

Cynthia, this is the company I plan to get my combination greenhouse / hothouse from. (I won the argument )
http://www.adloheat.com.au/index.html.

Have a look at "Products" they have some nice 1/2 GH /HH combinations, and I was looking at the 10' X 15' model, and they suggested raising it up on treated pine to give extra height and to make a better seal from insects.

Interested in your comments.

[Cynthia, Prescott, AZ]

Yes, in my opinion, the house is too short. It looks inexpensive compared to redwood and glass, but I suspect that it will take a lot more up keep. Actually, it reminds me of my temporary GH. Did I ever give you the web address for my GH pictures?
http://www.pbase.com/schnitz/temporary_greenhouse
I put piers in the ground to tie it down. It rattles very badly in our high winds. If you will be growing in this for some time to come, definitely put it up on a block wall or other kind of wall, but I would look carefully into how sturdy this is going to be. Cynthia