Help with yellowing plant! Pictures

[mogirl92]

Hi, I am a 20 year old who love orchids!! I study botany in college and had an internship this last summer with the Missouri botanical garden. I have several orchids and they have all been doing good since I had them. I currently have 17 different orchids of every shape and size. I have noticed in the last couple days that on 2 different orchids that a leaf on each one has been yellowing. Both of these orchids look very healthy besides these one leaves. They both have new growth. One of them is a mature plant and has flowered several times before. This one I checked on the root system and it is very healthy. I make sure not to over water any of my orchids. I was always taught it's better to under water them than over water. Could these leaves be changing due too much light? In my past when this was the issue the leave would get more reddish in color. I attached 2 pictures of each leaf that is yellowing. Any advice or help would be appreciated. Also these 2 orchids are not next to each other. Thank you all in advance.

[cbuchman]

Too much light is usually indicated by a reddish hue to the leaves. Since you've checked the roots, over watering, doesn't appear to the culprit. have your check for 1) bugs, 2) temperature changes, or 3) it could just be older leaves dying.

That's all I can contribute, the better experts may be able to help more.

[Eddie Oates]

Don't worry about it you have no problem with the cultivation all orchids at some point have yellowing leaves. Just wait until they almost look dead ( dried) and then press down on the leaf as close to the plant as possible and the leaf will come away.

[Phalchid]

Those yellowing leaves are at the bottom, so they are the oldest, and may eventually fall off! Nothing to worry about!

[mogirl92]

Thank you all so much!! That's what I was starting to think but I wasn't really sure!! I'm glad that there is nothing to worry about! Once again thanks everyone!

[silken]

They look to me like the natural aging of older leaves. However I notice in the 2nd photo and possibly even the first photo that the plant is over-potted. Too large a pot can often lead to root rot. At least it sounds like you understand the part about over-watering so it may be OK. But as a rule, they are usually potted in a pot just large enough to contain the roots and possibly a year's growth.

[RosieC]

I agree that it looks like natural aging, but like silken I think they are over-potted which could lead to problems in the future.

[mogirl92]

Thank you so much for the suggestions. I was taught that same rule for pots with orchids. The first picture is actually in a tiny pot. It's about a 4-5 inch pot. That orchid is also several years old and has more shoots on the other side of the pot that you can't see. I agree with the second picture that orchid is in a pot that is to big for it. That is all on me because I know/was taught that they need smaller ones. Thank you for pointing that out to me.

[King_of_orchid_growing:)]

These are just my thoughts on the potting medium for the Dendrobium...

The leaves may signify yellowing of older leaves on a semi-deciduous type of Den.

However...

If the yellowing is really not due to older leaves aging and falling off, and it is an early indicator of over watering - then may I suggest changing the potting media from moss to small grade bark to provide for better gas exchange in the area around the roots.

If you haven't known or haven't been told already, most epiphytical orchid roots, (including your Den), have roots that are capable of photosynthesis. Just a fun thing I like to spread around.

Sometimes, the photosynthetic process the roots provide can be far greater than that of the vegetative portion of the plants themselves, (depending on the species, of course). An extreme example are the Asian Ghost Orchids, or the true Ghost Orchids.

[mogirl92]

Thank you so much for the advice! The potting medium is actually a small grade bark. I only have the moss on the very top. Thank you for that interesting fact. I found that very interesting, I have never heard of that before. Thank you for taking your time to write. I will keep in mind what you told me!