Relative Humidity

[sarraceniac]

I'm a rapidly learning newbie and I voted 50-65% based on an average (I'm brilliant at math) of what I'd read. I obviously don't grow anything esoteric yet but that is what I've been aiming at (about 60%) so it had better be right.

[remo]

My greenhouse collection consists of phals, catts, oncids/intergenics and I keep it about 75%rh. It seems that the higher the temp they want higher rh. I keep it about 62 at night, in the morning go to 65, then to 76 in the afternoon, early evening/sundown back down to low 70's, then down to 62. Sometimes at night the rh goes as high as 85% if I watered that morning, but I have 2 fans always on low moving the air. So far so good, lots of growth and phals in spike now. This is a new regimen for me and I'm still a bit nervous about it. We'll see...
Remo

[smurphr]

I voted for over 75% because that's the humidity here where I grow my orchids 24/7 outdoors. Only in the drier months Dec - Feb does the humidity fall below 75%.

[Miller]

A shade house in in my future at some point, how do you even get humidity that high mechanically in a shade house?

I was talking to another orchid enthusiast this afternoon and we got talking about the humidity within our growing environments. This conversation came about as he had come around to my place to take some photos for me of Cyrtochilum edwardii X Baptistonia echinata(photos to come). Before he took the photos I showed him my new shade house/green house, and he said ‘hell its humid in here’. My reply was it’s 90% and the temperature is 25 degrees C = ~ 76degrees F and I don’t let it drop below 80% and I only have to water once per week when I fertilize. His reply was that he was working on 45 -65% humidity. I pointed out the Ondidium Sharry Baby’s in spike, no spotting on the leaves the Encyclia cochleata’s in flower (2 open on each spike)(mounted with roots everywhere)the Encyclia Ciliare in a hanging basket with 75mm long green aerial roots. To say he was gob smacked is an understatement .

My question is What is The IDEAL humidity level to grow a mixed collection including Cats, Brassia, Oncids, Zygo’s and Dendrobs?

[Dorsetman]

The answer in my opinion is like this ;the lower the humidity, the more the plants are stressed ; stress is not always bad by the way, in leading to bud formation , but it has to be for a short time or the stress damages the plant. However, the higher the humidity, the greater the potential risk from moulds bacteria, fungus etc - they all flourish very well in high humidity.
remember too that in the wild, humidity cycles from low at noon to high at night ( it is if course Relative Humidity to give it the proper scentific name - the same amount of water is in the atmosphere, but the air gets thinner as it warms, hence RH drops, and vice versa). I once took RH readings in a Reserve in North Thailand ( home to Vandas, Paphs, Dendrobiums, etd etc... ) and got figures varying between 95% just before dawn, and 35% at mid-day - although soon after that it clouded over, and then began to rain, and the figure shot up.
In my greenhouse, with my heavy spraying , it is certainly high - over 90% in the first part of the day, but in June, if the sun shines non-stop, the greenhouse temperature rises above 30 (C) and then I leave the doiuble doors wide open, and figures of 40-50% are the norm. in the winter, with lower temperatures, I worry moe about fungal infections and rots, and aim for lower figures for more of the time.

[kspalding]

Guess it depends on what ur mixing. All my orchids do well in 65-75 except for my one masdevallia suffers. Its hard to find a cool enough spot for it in Florida . I wonder if I stick it in the fridge would this help (or am I ).

[Wade's Orchids]

I voted 65 - 75%. Humidity is very variable. Near the floor of the greenhouse it can be above 80% while the plants hanging in the sun are at 30%. Also, high humidity requires more air movement to minimize fungal and bacterial growth.

[Kauaiguy]

If anyone think that Hawaii is the perfect environment for growing orchids, who is to argue? After all, an awful lot of orchids come from Hawaii and the humidity here is normally around 65 to 75. Today it's 77.

However due the the wet nature of Kauai (that's why it's called the garden island), where it rains almost daily, the humidity is probably slightly higher than most places.

[Arne]

I try to get the humidity as high as possible during the cold time of the year when the relativity humidity drops upon heating to the indoor temperature. Then I found that 50 - 65% is sufficient and if I try harder it hurts everywhere, especially the wallet.

[Kauaiguy]

Maybe great for growing orchids, but NASTY for anything electronics! I have a $2,200 Keyboard where I constantly have to replace it's components due to humidity. CORROSION and MILDEW are the most common problem living in such an environment. RUST! Most of the old cars here that are kept outdoors have rust! ... and as my son says " It makes no difference if you purchase a top of the line item ... if it has metal and or electronic components ... it's doomed to fail within 2-3 years.

Garden Island you say? Paradise you say? ... yeah but it has it's drawbacks. Not to mention shipping items from the mainland (lower 48 states) to Hawaii costs an arm and a leg!
Just bought a $4.25 (25' guitar cable) ... shipping ? USPS ... $7.85 ... Ouch!