oncidium pseudobulb shrivel - Orchid Board

epl · #1 07-20-2007, 02:20 PM

When i got my oncidium it had fat firm pseudobulbs with nice green leaves and a nice flower stalk, but now the pseudobulbs are wrinkled, the leaves are a bronzish green color, and the new leafs that it has are deformed. Can anyone tell me why this is happening and how to fix it? Also, how do i post pictures?

slipperfreak · #2 07-20-2007, 04:17 PM

It sounds to me like you haven't been watering it enough, or the roots have rotted from too much water. The shriveled pseudobulbs mean that the water within them is being used to nourish the plant due to lack of water at the roots, whether they just haven't received it or have rotted and died. Corrugations at the leaves are caused by a non-constant watering schedule, ie you water lots for a period, then stop watering. It could also be caused simply by lack of water. I suggest you unpot the plant and examine the roots to get to the bottom of the problem.

epl · #3 07-20-2007, 04:49 PM

I took the plant out of the pot and looked at the roots which were not roting as far as i could tell. I have it potted in sphagnum moss that i water when it gets dry. When i examined the plant i found a new leaf that appeared to be ok. Also when the pseudobulbs get better how do i get it to bloom again?

slipperfreak · #4 07-20-2007, 05:06 PM

Okay what you'll want to do now is repot it it in a bark mixture with sponge rock and charcoal; the grade depends on the type of Oncidium you are growing and the size of pot, but the standard grade is medium. Choose a plastic pot (preferably clear) that allows for two more years of growth and that the roots fit into fairly snuggly; there shouldn't be more than 1-2" or so of space between the roots and the pot sides. Make sure when repotting that any dead (soft and hollow, and brown) roots are cut off using a sterilized tool. After repotting soak the pot in a bucket of water for maybe 12 hours or so. This will rehydrate the roots and after a week or so the pseudobulbs should return to normal. Afterwards keep it evenly moist but make sure it doesn't get wet; let the pot dry out down to the last quarter or so before watering again. Keep an even watering schedule and you won't get any more leaf corrugations (though those that have already appeared will not go away). To rebloom, make sure it gets sufficient light (most Oncidiums like it quite bright as in a west or shaded south window) and make sure that you have a 15-20F differential between day and night temperatures; this will initiate the flower spikes. A difference in summer and winter temps, and perhaps reduced watering during the winter, will also help.

epl · #5 07-20-2007, 05:34 PM

Thanks, I'll try to get that done tommorow.

Lagoon · #6 07-20-2007, 07:24 PM

Why not leave it inside the media and pot that it's in now and water it more often

Perhaps the waterings aren't deep enough?

The bulbs should begin to fill up within' a short time, few days maybe - You just have to keep it moist. Allow the bulbs to be your guide, if the bulbs start to shrink again, then you need to water it deeper or more often.

Mine are growing great in sphag moss with addtional coarse rok.

slipperfreak · #7 07-20-2007, 07:32 PM

Gloria's suggestion would work too, but in keeping it more moist (which apparently needs to be done) you have to be careful not to overwater as wet sphagnum can cause rot. I have to stress this because the number one cause of orchid death is overwatering. A clear plastic pot really helps to tell if the plant needs water. You could also add some perlite or something to the sphag to make it better-drained. What you choose to do is totally dependent upon personal preference; in bark it is harder to overwater but easier to underwater, so if you are a frequent waterer then the bark is better. If you tend to leave things dry, perhaps the sphag is better. This will also depend on the type of Oncidium you have; the fine-rooted types like sphag or fine bark best.

Lagoon · #8 07-20-2007, 07:45 PM

Joe, I can completely understand the fear of pure sphag and rot. I was there too 1-1/2 year ago.
2 Things I have found .. when you keep your sphag moss renew every 9 months you leeson the chance of all that moisture build up - the soppy soaking.
And # 2 When you add large coarse rok (perlite) It changes the whole sphag experience. What you end up getting is ... lots of moisture, added quick drainage with lots of air.
I got my catts in this mix, they thrive - who knew?! LOL!
Don't give up or fear this moss until you tried in a different way.

Regards,
Reformed sphag hater

PS -- There's nothing wrong with bark if you grow well in it

slipperfreak · #9 07-20-2007, 07:52 PM

Well you see there are just so many combinations of different materials to use, the list goes on, and everything changes with varying conditions. I hope we haven't confused you epl! The important thing is to use what works best for you. Experiment a bit, and eventually you'll find something you like best. The aim is to get moisture retentiveness and drainage at the same time. By the way Gloria, I don't fear moss, I still have my uses for it, I just don't like using pure moss on mature plants. That's interesting, though! I think I'll try it with my Odontonia, which needs repotting soon!

Ray · #10 07-21-2007, 08:49 AM

The key to growing epiphytes is maintaining lots of air flow to the root system, while still providing moisture and nutrition via the medium.

The challenge with moss is not having it get so compact that it suffocates the roots.

Back to the initial query: Nobody seems to have picked up on the leaves having a "bronzish green color". To me, it doesn't sound like the issue is "not enough water" as much as it does to hot, bright and dry - so much so that it is outstripping the plant's ability to absorb enough water to maintain the absorption/loss balance.

The coloration suggests too much light, and the deformed leaves (I'd guess "pleating" as we normally call it), suggest insufficient humidity. The higher leaf temperatures driven by the high light levels would cause the plant to lose more moisture in any humidity level, and if the plant has insufficient moisture reserves, it has a hard time "pumping up" the plant tissues as the new leaves grow.

Simply adding water to the balance through the medium will not solve the problem(s), and will likely lead to others.