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My orchid's leaves have turned into a reddish/brown color recently. Is it receiving too much direct sun (spring has started here, but is was also in this location last summer and had no problems) or is something else going on?

The only pictures of "burned" leaves I could find had a more yellow color than mine.

The leaves were a bright-green color in the past (like the color in the center of the leaves). It is normally in front of a south/west facing window. It has been flowering for quite a while now.

top-view of orchid

Update in June: The newer leaves have turned back to green. New leaves are appearing. Fertilizing definitely helped. Here's a picture of how it looks now:

enter image description here

Source

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This looks like phosphorus deficiency. When was the last time you added fertilizer, how much and what formulation? Possibly magnesium deficiency. Did this discoloration start at the margins to spread towards the mid vein? Best to know what you have added to the potting soil of your orchid. Is this primarily found on the lower or older leaves? When there is a shortage of a mineral/chemical the plant needs to photosynthesize and survive the plant will always send to the young growth at the top as the best survival mechanism.

Phosphorus as are all the other chemicals (nutrients) plants need to photosynthesize when really low or insufficient actually promotes the making of anthocyanin (sp?) thus the purplish color. Your flowers will be wimpy and thin. ATP is energy for us for plants. For most of life. When ATP is broken down to ADP, Adenosein triphosphate to Adenosein diphosphate that little chemical change makes energy. See that last part with the phosphate? That is phosphorous. Lacking this P will cause a plant to slow way down.

If you have fertilized, one thing that would cause this plant to not be able to take up the available phosphorous is the temperature of the soil. If it is cold and phosphorus is in the soil the roots will be unable to use this chemical.

Fertilizer is needed in SMALL amounts. Excessive fertilizer is actually worse than too little.

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  • It is not cold, but lack of fertilizer could indeed be the problem (last time I used fertilizer is a while ago.... oops). It is in a mix of normal potting medium for houseplants and special potting medium for orchids (it used to be in normal potting medium, I tried to replace most of it by orchid potting medium because it didn't drain so well) – user53923 Apr 12 '17 at 7:40
  • The flowers look normal to me though (compared to previous flowerings) – user53923 Apr 12 '17 at 7:41
  • So if I fertilize correctly, should the leaves get their normal color again or will only new growth (if any) be green? – user53923 Apr 12 '17 at 7:43
  • Yes, for this instance those leaves will have their chloroplasts rejuvenated and that is what makes them green. If you haven't fertilized for a while this advice will be perfect, definitely won't hurt but I am fairly sure that is what is happening. Orchid soil is great, but I never buy soil with added fertilizers. I like to know what and how much I've applied. Send me a picture in one week and then in two! Please. Do not use fertilizer where the N is higher than the P and the K in percentage. Even numbers is ok but N higher in % than P and K will promote leaves not flowers. – stormy Apr 12 '17 at 21:24
  • Seems like this was the issue. The leaves (or at least, the newer leaves, some very old ones died) returned to a normal green color :) and new leaves are forming – user53923 Jun 27 '17 at 14:06

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