constant water at leaf intersection on phrag. besseae - Orchid Board

bard · #1 12-08-2009, 11:15 AM

I am growing my phrag besseae in pure diatomite in a 4" clay pot sitting in 3/4" of rain water. It is growing beautifully and has been for over 2 years, repotted last June. It blooms regularly in the early spring. My concern is this I recently noticed water at intersection where the newest leaf joins the one before it. It seems to be present at all times. I don't recall seeing this before and wonder if it may be problematic. The plant is in a large, homemade growing case with an average RH of 75%, daytime winter temp of 72f and night of 58f, full spectrum lighting and several fans for air movement.

phragguy · #2 12-09-2009, 09:13 AM

I would think it can't be good come night time. I wonder where it is coming from. Dripping from the top somewhere from condinsation?

bard · #3 12-09-2009, 09:43 AM

That's a good thought but it is not the cause the fans eliminate all condensation except rarely small amts.on the plexi sides and doors just after misting. The fans are so effective that all water droplets are gone in 2-3 hours after misting even with 80%+RH. It seems like the water is wicking up from diatomite in the pot. I am reluctant to change the system I am using though since the plant seems so healthy. I wonder if it may be normal to get water retention at the intersection of the leaves when the pot bottom sits in water. By the way I am careful not to mist the plant when I mist other ones so as to prevent water from entering from above. I wish others would carefully check their plants growing in a similar way to see if they too have water there. It's not that obvious and easily missed.

Ray · #4 12-09-2009, 09:44 AM

My thought is like Bard's, exactly. One thing that might be playing a role is the humidity level. Consider this scenario:

If you have 75% RH at 72°F in the daytime, the air will reach saturation at about 63°, meaning that it will be "raining" as it passes that on its way to 58° nighttimes. Then, with that elevated humidity, droplets trapped by the leaves will be slow to evaporate, leaving them there at all times.

Water will not wick up to the top of the plant.

bard · #5 12-09-2009, 09:56 AM

Thanks for that Ray. It makes perfect sense but why don't I get any water retention in the leaf intersections of my phals and paphs? That would really worry me. The phals are in pure spagh. and the paphs in coco husk, sponge rock and charcoal. Also there is no visible moisture in on the plants or walls when the lights come on in the AM. The fans run 24/7.

bard · #6 12-09-2009, 10:21 AM

I just had an additional thought. In a cloud forrest I believe it mists heavily every night yet orchids thrive so my condition, if cause by nighttime "rain", may be normal for some orchids. The only problem with that is that Masdavallias and I believe most cloud forest plants have single leaves.

bard · #7 12-14-2009, 05:48 PM

I think I have an explanation for the water at intersection of leaves on my Phrag. Besseae. I mentioned the problem to a friend who retired as a researcher in Plant Science at CU. He designed and built several climate chamber growing cases similar to mine and I consulted him when building mine. He suggested condensation might be causing the condition and it appears he is right. During the day yesterday I dried the plant by tipping it to drain the leaf intersection and placing a fan so that it blew directly over the plant until it was dry. At 8PM last evening, 2 hours after the lights went off, I checked the Besseae plant. The temp was 72f, the RH was 75% and it already had fresh droplets of water on the leaves. I blotted them and checked again in an hour. The droplets had reformed and some had run into the leaf intersection. This time I left them but opened the doors an inch on each end, At 6 AM when the lights came back on the plant was dry and the RH was 55%. It seems the opening the doors slightly lowers the RH enough to eliminate the water retention issue. No other plant had any visible droplets on it . I assume the thinness of the Besseae leaves causes them to cool faster than the other thicker leaved plants. The still warm water vapor in contact with the cool leaves causes the water to condense and run down the leaves. I wonder if this happens in nature too?

NickEngler · #8 01-13-2010, 12:03 PM

I was struck by how high the humidity in your case is, and for Phrag besseae is probably higher than is really necessary. In the Ecuadorian highlands where besseae was originally found (NE of Cuenca) the humidity is only transitorily around 90%. Average humidity is closer to 50-60%. This is about how high my humidity is, not just for the phrags but for all my plants -- because I'm an in-the-house grower I can't get much higher than that without damage to the house. Supposedly in their native habitat the plants grow in or near streams or water seeps where the roots are always quite wet, and where admittedly the humidity might be a bit higher than the surrounding air. The water is also fairly pure so they are a perfect candidate for S/H culture. It has definitely saved my phrags and made them grow better.

The besseae is one of the more difficult for me, even in S/H. About once a month I run water through the media and pot for about 5 minutes and then re-water with RO. This seems to keep the media cleaner and the plant definitely does not like algae build up around the roots.

bodaciousbonsai · #9 01-24-2010, 05:59 PM

As far as algea buildup around the roots. I use 1/2 tap 1/2 R.O.. I also use dechlor for the water at 2 drops per gallon. this eleminates the build up of algea. I have been using this watering schedule for the past 10 years & have had no ill effect what so ever.

NickEngler · #10 01-25-2010, 10:52 AM

Is that dechlor the kind used for fish tanks? A friend suggested using a weak solution of Physan 20. Any thoughts?