Brown leaf tips on phrag

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Hi all,

I've got a phrag longifolium x dalessandroi with brown leaf tips. I cut off the tips a couple of weeks ago, but it continues to spread. It's growing under lights in the basement, about 45% humidity. I fertilize lightly every couple of weeks. I use tap water, which is not too bad here. I can't figure out whether this is a disease or a consequence of its growing conditions. Advice appreciated. Thanks.

Rich


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It was repotted this past September. The roots are not good. There are some dead ones (soon to be removed) and a few that look pretty new and healthy. I think that I may not have been watering it sufficiently until recently when I learned more about appropriate care.
 

abax

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YES! Under watering is perhaps the answer. My greenhouse is very
humid and I thought I was watering enough. I've been tweaking
my culture with more frequent watering and new growth is without
browning. I also fertilize with every watering...say every three days
or so.
 

Ray

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I have seen that happen when one or more of the following are happening:
  • The mineral content of the water is too high, especially if it’s alkaline.
  • The fertilizer concentration it too strong.
  • Mineral buildup in the potting medium.
If you can provide some details around those areas, maybe we can offer more help.

kelpMax should help with root recovery, unless something else is working against it.
 

abax

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Actually Greenpaph, sitting in water is not the
same as water running through the potting
medium improving air flow and fresh water.
 
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Thanks for the reply, Ray. I got Kelpmax from you a couple of weeks ago and have begun using it according to directions. The water here is pretty good (as you said in an email in response to a question I asked with my order). It's potted in a mix of small orchiada, lava rock, sponge rock, and hydroton. It was repotted 9 months ago, but it seems like the mix is breaking down faster than it should.

There is some water in the tray, as seems to be widely advised here.
 

Ray

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In contrast to my earlier comments, others have seen leaf tip dieback from underfeeding.

What, specifically do you mean by "I fertilize lightly every couple of weeks"?
 
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I was fertilizing with Grow More 20-10-20 Urea Free Orchid Food until a couple of weeks ago. Every other week, or so, at no more than half the recommended strength. I've now switched to K-Lite at the low strengths you recommend.
 

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And what is the recommended strength for the 20-10-20 fertilizer?

I was fertilizing with Grow More 20-10-20 Urea Free Orchid Food until a couple of weeks ago. Every other week, or so, at no more than half the recommended strength. I've now switched to K-Lite at the low strengths you recommend.
 

Ray

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1 Tsp/gal of a 20%N formula is about 265 ppm N. My personal target is about 100 pm N per week, so 1/2 the "recommended dose" is slightly high by comparison, but of no consequence.
 

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