P. corningiana - odd leaf colouring
 

Hi Folks,

I was hoping you might be able to help me out - I have a P. coringiana that's been growing really well - nothing has changed the watering/fertiliser cycle is the same, I'm growing it at a constant 28oC and 80% RH to promote vegetative growth - I've got it in a growth cabinet so I have a 14hr lights on, 10hr lights off cycle but there's discolouration to the leaves. My gut feeling is that it's getting burnt by the intensity of the light but, at the leaves, it's only reading 1243fc any thoughts?

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I don't know if that's burn. But, I don't positively know that it isn't either. If the foliage has water on it, sitting close to the lights, it could possibly burn.

Hopefully others can help more than I.

firstly - Orchidwiz says that there should be a diurnal range of 7-9c. So 29c upper 21c lower
Further - which may be your problem - " corningiana is unusually sensitive to cold water which causes bud blast and cellular damage " They recommend a water temp of 21c to water.