Yellowing of vanda leaves?

[Lucinda Brown]

I've had a few vanda leaves getting either completly yellow tinted or just sections of some leaves yellowing here lately.I haven't changed my watering or humidity for them whatsoever.They've never done this before.I added liquid iron to there diets to see if it would help.No change,I use 20-20-20 fertilizer for them,once in awhile some bloom booster fertilizer now that summer is approaching.No sign of mites or other pests.Roots still look good,it's got me boggled Would some stronger nitrogen rich fertilizer maybe help?I've read that vandas don't like high nitro fertilizer.Does anyone know what causes this and what to do about it?

[kmarch]

How long have you had them and what is your watering regimen? I've never heard that liquid iron will prevent leaves from turning yellow. Tell me more about that, please. Also, are your temps consistent and warm? Any cold drafts or anythign like that?

[Lucinda Brown]

Varied amount of times,on how long I've had them.As to temp I try to keep it around 65 degrees at least at night,no higher then 85 degrees daytime.But I just got the evaporative cooler for the G.H. installed so it did get too hot a few times before this.I either hose them daily or soak them in there tubs with food that I have set up for them in G.H.The liquid iron is usually great help when a plant is not the healthy green it should be.House plants,outdoor plants,etc.This is only the second time I've used it for orchids.It really helped 2 yellowish 'newbie' plants I received awhile back,but doesn't seem to be helping the vandas much that I'm seeing this on.

[kmarch]

Thanks for the additional info. You mention that oyu only have a "few" plants doing this. Is the number of plants this is happening to consistent with normal old leaf loss? Or is this more than usual? If you have had Vandas for some time you are probably familiar with what is normal in this respect. Frankly...I'm puzzled.

[Lucinda Brown]

Me too,puzzled-that is.On some it's the older leaves,on one it's just half of one of the upper middle leaves.I think I'm going to try spraying them with some superthrive and/or maybe getting some worm tea,and see what happens.Don't know what else to try.

[kmarch]

Is it happening quickly or slowly? If slowly, I might be inclined to think it is just normal old leaf loss. Unfortunately I'm not a Vanda expert. I currently only own one.

[sandra]

Lucinda, I've heard nothing but outstanding results with the worm tea. I'm going to be ordering some tomorrow morning as well.

I'm no where close to knowing much about orchids and the various species but I have recently made an observation that typically, after I've fertilized, I notice a leaf here or there on my orchids turning yellow. Doesn't matter if it's vanda, oncidium or den.....they've all been affected when I used full strength fertilizer (30-10-10, and even fertilizer, strictly for orchids). I think it's safest to use 1/2 strength the called amount when fertilizing to prevent burn which would/could cause yellowing.