Let's talk Humidity...

[W. Beetus]

Now that I finally have gotten around to getting a humidifier for my greenhouse (have needed one for years, finally got a high quality one for GH use), I would like to get an idea as to what kind of humidity levels I should be setting the humidistat to during the day and night. My normal humidity levels without any help are only at around 30% in the day, and 40% at night.

I have mostly Parvi's along with a few multi's and a single Phrag. I was thinking of making my setpoint for the day at 55%, but am not sure if that is still low for what I have or not. I also have a Paph. roth x richardianum that is in bud (three buds, probably about 2wks out from opening the first bloom) and I do not want to blast it by upping the humidity. Is it not likely to blast since I am past the sheath stage? If it is going to be a problem, would it be advisable to raise the humidity gradually at 1-2% RH per day until I reach the desired level or should I just wait until it's in bloom to mess with the humidity?

If anyone would like to share their levels and what they are growing, it would be much appreciated along with recommendations of what I should be setting the humidistat at for day and night.

Thanks!

 

[Rick]

My data logger shows that my GH humidity is not dropping below 70% (usually during the middle of the day), and runs to 90%+ at night.

My Paph collection is loppsided to multis and barbatas I guess, but I do have a handfull of parvies and brachies.

I posted my collection a few weeks ago.

 

[gonewild]

Like Rick... said 70% and higher during the day and higher at night in the 85-95% range.

 

[Rick]

Before I added humidity control I used to run the same way as you. I didn't acclimate anything though and just shot for a minimum of 50% at first (mostly just to debug the system). Plant growth improved very quickly, so I pushed to 70% probably within a week of getting the system proofed. I probably was pushing the 70% min within a month of my humidity epiphany.


I think Leo tends to run a little dryer, and he has lots of parvis.

 

[Erythrone]

65 to 75% for the day

50 to 60% for winter night. I grow Parvis crosses, some multis, some species, some Maudiae, some Novelty....some Phrags...

 

[ehanes7612]

70 percentish at day...and just turn off humidifier at night...the drop in temp will keep humidity at acceptable levels and you wont run the risk of dew collecting on plants

 

[Rick]

70 percentish at day...and just turn off humidifier at night...the drop in temp will keep humidity at acceptable levels and you wont run the risk of dew collecting on plants

I don't know how tight other GH's are, but my old one was very leaky, and when winds came down from the North and the electric heaters came on to keep the GH about 55, the humidity in my GH would plumet to 30% or less at night. Winds from the South would push it up to the 40% range with supplemental humidification.

My new GH is much tighter, and I just leave the wet pad running 24/7. I have a fogger inside too, and set to come on at about 65%, but it hardly ever comes on in this new tighter GH.

Plenty of air movement to keep dew from collecting on plants.

 

[W. Beetus]

My problem too is because of the electric heat. It just sucks the water right out of the air. I figure that from what everyone else is doing, I will go up by 5% each day until I get to about 60-65%, and just make sure it stays above 40% at night. I will gradually increase it just so that I can make sure I don't blast the roth x richardianum buds.
My humidistat/thermostat combo unit has different setpoints for night and day, so I won't have to go in and change it manually.

 

[Ross]

Just a comment: as you increase the humidity, make sure to increase air movement accordingly.

 

[ehanes7612]

I don't know how tight other GH's are, but my old one was very leaky, and when winds came down from the North and the electric heaters came on to keep the GH about 55, the humidity in my GH would plumet to 30% or less at night. Winds from the South would push it up to the 40% range with supplemental humidification.

My new GH is much tighter, and I just leave the wet pad running 24/7. I have a fogger inside too, and set to come on at about 65%, but it hardly ever comes on in this new tighter GH.

Plenty of air movement to keep dew from collecting on plants.

yeah, if you have to heat, definitely add humidity

 

[gonewild]

I would suggest that the night humidity should be higher than the daytime humidity, or at least equal to it. Going from high humidity in the daytime to lower at night is opposite to most natural environments.

 

[Rick]

I would suggest that the night humidity should be higher than the daytime humidity, or at least equal to it. Going from high humidity in the daytime to lower at night is opposite to most natural environments.

True (because of the lower temps). Keep in mind that dew on plants in the morning is a natural phenomena that also happens to wild parvis. Many plants and animals in more xeric conditions count on that morning dew for their water supply.

I don't manually reset my humidity control systems to run differently at night than during the day, but because of the temp drop, the humidity naturally goes up at night in my GH.

As noted in my previous post, then without humidity control in place my GH would plummet at night if I turned it off.

 

[Erythrone]

By reducing humidity at night, I have less problem with rot.

 

[ehanes7612]

By reducing humidity at night, I have less problem with rot.

YES!

 

[Rick]

By reducing humidity at night, I have less problem with rot.

I've noticed the opposite in my collection. Particularly in summer when I have heat stress induced problems.

 

[gonewild]

If you have less problem with rot by reducing night time humidity then you probably don't have enough air movement at night.

You can probably assume that most orchids prefer humidity above 50% at all times.

 

[gonewild]

As noted in my previous post, then without humidity control in place my GH would plummet at night if I turned it off.

The same for me. I have my growing area set with intermittent foggers that cycle all day but cut off in the afternoon in time to dry the foliage for night time. But then at night the humidity drops too low. So I have installed a separate fogging system under the benches that runs at night to keep the humidity high.

 

[Erythrone]

If you have less problem with rot by reducing night time humidity then you probably don't have enough air movement at night.

You can probably assume that most orchids prefer humidity above 50% at all times.

Well... I have 12 fans running all day long in a room of 12 x 12 ft. And 4 of them are rather large.

In fact, I don't reduce humidity in summer nights (Anyway I am unable to this with my extraction system. Relative humidity is hight here in summer time). But I discovered that I must do it when the weather is cool and the photoperiod very short.

By the way, RH is always higher than 50%. I think you are right. 50% is the minimum for growing good Paphs and Phrags, and higher is better. It is good for the auxilaries that I introduce too. But I must sometimes deal with disease.

 

[W. Beetus]

Just a comment: as you increase the humidity, make sure to increase air movement accordingly.

Very good point. If I am going to get up to the 60% range, then I probably should just add another fan. I currently have one very strong 12" one and aim it at the ceiling. This keeps the leaves on some of my other plants moving, but more circulation couldn't hurt!

Before I even get the level that high, I need to set up some kind of water source for the humidifier. It currently is going through about a gallon per day just raising the humidity to 35%. It has a float and connection for what looks to be 3/8 tubing, so I probably will have to connect that up to some kind of reservoir and use gravity flow.

 

[Ray]

I used to grow a lot indoors, and used a large ultrasonic humidifier. So that I wouldn't have the issue of refilling a small tank, I removed it altogether, and drilled a hole in the lip of the base that acted as the reservoir wall. I siliconed a piece of vinyl tubing through that hole to act as a drain, and used a small pump to push water up from a 5-gallon bucket, so I had a "closed loop" to keep the humidifier fed, but only needed to refill the water every few days. Adding a float valve and "active" water supply to the bucket would have automated the whole thing.