Oncidium incurvum help needed!

[Helen]

Hi everyone.... the last few days my oncidium incurvum leaves are starting to yellow and get soft and drop off.. I lost approx 5 of them and a few more are starting to yellow. My watering has been irratic due to hot then cool weather here in southern ontario....any suggestions?
Am I over or underwatering? I really don't want to lose this one...I'm having so many problems with almost every orchid I own that I'm getting discouraged....at least my new brassia is blooming, so that gives me the 'oompf' to keep at this....!!

[Helen]

Thought I'd add some pictures of the limp yellow leaves.
Thanks everyone!

[Oscarman]

Yellowing of leaves (other than natural age related shedding) immediately sets off my overwatering alarm.

Here is a little cultural info:

LIGHT: 2500-3500fc. Light should be somewhat filtered or diffused, and plants should not be exposed to direct midday sun. Strong air movement should be provided at all times.

TEMPERATURES: Summer days average 73-75(23-24C), and nights average 57-58F (14-15C). Because of the range in distribution and habitat elevation, plants should adapt to conditions as much as 8-10F (4-6C) warmer than indicated.

HUMIDITY: 70-75% most of the year, dropping to 50-60% in winter.

WATER: Rainfall is moderate to heavy from late spring into early autumn but decreases considerably into a dry season that extend through winter and early spring. Cultivated plants should be often while actively growing, but drainage should be excellent and conditions around the roots should never be allowed to become stale or soggy. Water should be reduced after new growths mature in late autumn.

FERTILIZER: 1/4-1/2 recommended strength, applied weekly when plants are actively growing. Many growers prefer to use a balanced fertilizer throughout the year; but others use a high-nitrogen fertilizer from spring to midsummer, then switch to one high in phosphates in late summer and autumn.

NEVER give up Helen! We are all here to support you.

Although many of us would never admit it......we have all killed some as we learned to grow what suits our conditions first and what suits or fancy second.

I maintain a plant pot of tags from those I have killed to remind me.

[Helen]

Dave, thanks very much for the encouragement...I really need it right now....I thought maybe I was underwatering because most of the roots are high up on the plant and I noticed when the roots are white the medium looks drier, and when I water, the roots turn green.

Do you think I should repot into all sphagnum moss? right now it's a blend of small bark mix with charcoal and moss. Or, perhaps the moss is keeping it too moist? I'm getting myself very confused right now.

[Helen]

Also, I forgot to mention that perhaps the pot is way too big for it....I think I'm going to downsize...just need to know into what medium...(that's why I see the roots so close to the top...the pot is very big for the size of the plant)

[Gin]

Hi Helen ,
Don't give up ,I would put it in as small a pot as you can in the bark ,Oncids. have a habit of growing roots on the top of the medium , if in dry conditions I sometimes add mix over them once they have some length , if kept to wet when short they sometimes rot . Just looking at the picture I would say to large a pot .causing it to stay to wet in the middle , no air to the roots ... Good Luck with it ... Gin

[Helen]

Gin, I think you are absolutely correct...I just took it out of the large pot.. The roots looked surprisingly good....still white with a few darker ones but still firm...and TONS of them! (I had way too big bark and charcoal in the pot which stayed wet for a long time I guess...) I think you are right, not enough air getting to middle and yes, there are a lot of roots growing on top, high up that I can't put under the mix. I repotted into a smaller pot with smaller bark/perlite and some of sphagnum mixed in...this plant was a seedling I bought in March of this year.. I am not going to water for a day or two....at this point I'd rather see pleating than yellowing...do you agree? THANK YOU !!!

[Gin]

Right on Helen ! as long as it has roots it should snap out of it . You are welcome Gin

[Helen]

Originally Posted by Helen

Gin, I think you are absolutely correct...I just took it out of the large pot.. The roots looked surprisingly good....still white with a few darker ones but still firm...and TONS of them! (I had way too big bark and charcoal in the pot which stayed wet for a long time I guess...) I think you are right, not enough air getting to middle and yes, there are a lot of roots growing on top, high up that I can't put under the mix. I repotted into a smaller pot with smaller bark/perlite and some of sphagnum mixed in...this plant was a seedling I bought in March of this year.. I am not going to water for a day or two....at this point I'd rather see pleating than yellowing...do you agree? THANK YOU !!!

Well, things are not going too well with my oncidium incurvum....even though I repotted and didn't water for days, the leaves turned yellow and then brown and have now ALL dropped off...the psuedobulbs are now yellow...looks like I've killed her! I don't understand what went wrong....seems like it didn't like watering then didn't like it dryer....guess it wasn't meant to be....
I'm just going to let it dry out completely now and see if anything else happens......does anyone think I should stick it in a bag with sphag? or is it too late for that now?

[shakkai]

Helen, I'm so sorry to hear about your plant! I'm not sure exactly what went wrong... but try to look at it as learning experience, and above all, don't give up!

By looking at how orchids grow in nature, I learned that they are not particularly suited to being stuck in a pot. In nature, nearly all of their roots are completely exposed to the elements (and air!) - so I figure this is quite important to try to replicate in their adopted home. For the ones with pseudobulbs, they have adapted to be able to withstand regular dry periods - that's what the pseudobulbs are for! They suck up water from downpours of rain and store it until the next downpour. So, I make sure that they are growing in something that allows plenty of air circulation and quick drying to allow the roots plenty of time to 'breath' fresh air. (I have also read somewhere that part of the gas exchange process of the roots gives off gas that, if it can't escape, can become toxic to the roots. So unless there is air circulation around the roots, they can end up killing themselves off. Too fine a mix will reduce air circulation, too much water making the mix too heavy will reduce air circulation, too large a pot will dry unevenly and the centre -where the roots are - will stay too moist and not get any air circulation, etc. To my mind, the only reason we use bark or whatever medium is simply to hold the plant in place in the pot (for non-terrestrial orchids, of course)!

Thinking about it this way really helps me to understand better just what my orchids need.

I don't know what to tell you about this one.... but maybe looking at things this way might help you with some of your other orchids? Keep your chin up, Helen!!