Orchids dropping leaves
 

Hi...I've been growing orchids for several years. Last year, I had them in a shade house until the cold weather and have brought them in the house. They have been in the house now since maybe the beginning of November or maybe earlier but not much (north Florida). I have them in front of a northeast window on shelves with clear plastic wrapped around the shelves and just recently added clear plastic to the front of the shelving to keep them moist because they were drying out too much with the fireplace and heater running.

The problem that I am seeing more recently is my orchids are dropping their leaves. There is not one type of orchid but many...vandas, oncid, phals, etc. The leaves started dropping before putting on the front sheet of plastic, so I don't think it has to do with that. The leaves are green and they look just like any healthy leaf on an orchid. I mist them daily sometimes twice a day. I also misted them lightly in the evening because of the dry before putting on the front plastic. I water about every week to week and a half sometimes 10 days and use fertilizer every other watering.

Any ideas what could be going on? I just don't know what's happening to them. I expected some to die, which I have had a few do because of the change and them being young, but this problem I just don't know what to think. :(

Do you have single pane glass? If you put the plastic between the plants and the heat source it could be that the temperature drops to far during the night.

Try to measure the minimum night temperature close to the glass during the night.

Any pics? It would be one thing if you had yellowing first followed by the leaf drop but you say that healthy green leaves are falling. I'm in N. FL also and have my plants under lights and next to a west facing window. Haven't had the first problem. Have you seen any bugs? Maybe you have too much moisture and the leaves are dropping due to water remaining in the cracks or the leaves where they attach to the base of the plant. Someone with more experience should chime in here shortly. Pics will help to be more precise though.

Sounds strange to me. Pics would definitely help.

Have the leaves gotten darker before falling? From end-November to end-January is the lowest sunlight. You've got some high-light orchids, and some low-light orchids - are they reacting equally or are the Vandas more affected. Is the leaf color on the phals a really dark green? If so, for sure not enough light for Vandas. I grow my Vandas outdoors with a couple of hours of direct sun - just a pane of glass will cut the light somewhat. If I put my phals near the Vandas, they wouldn't survive a day, and if I put my Vandas near the phals they would waste away slowly from lack of light.

No matter what else - have you looked at the roots? What are you growing in? Could they be drying too slowly in the plastic tent?

Sorry I don't have answers, but maybe the questions will help.

Stop the misting. Cold and wet is not good. Dry and wet is okay. You are wetting the leaves and then they get chilled.

Yes, I agree, stop misting. That does not add to humidity, but can cause rot if the moisture gets down into the leaf axils. This is especially true if the plants are wet overnight.

I agree about the misting I have a few Vandas they are in the greenhouse when it is cool no sun I skip watering them altogether or just water the roots that are hanging some are in baskets with no medium or hanging from a wire .

Thanks everyone for your responses. There are several things that I need to look at and possibly figure out what the problem is.

Ron, I didn't think about the temp from the window being a problem. I was thinking just the opposite...too much heat from the heater and the fireplace. I'm checking the temp now and will until morning to see what it measures.

Joshua, that was my first thought was bugs or something, but I didn't see anything. I've looked at the roots of most of the plants, and they look really fine to me. Minimal dead roots but definitely good roots.

Bob, the leaves are quite dark, and the vanda's are more affected than the other's. I'll need to keep my plant lights on a couple hours during the day then.

I will stop the misting or at least very minimal misting early in the morning.

I've uploaded 2 pics, a couple of the fallen leaves and the shelving I have my orchids in.

Thanks everyone...there's so much to learn...lol