Repotting oncidium alliance question
 

I finally got the hang of growing oncidium alliance orchids--now I have an other problem. It was time to repot 2 oncidium noids and a Mtssa Royal Robe Jerry's Pick; I last repotted them 2 years ago. Over the last 2 years they developed a lot of new p-bulbs and roots. I soaked the pots for a few hours, took the plants out of the pots--actually I had to cut the clear plastic pots off--then I soaked them overnight to try and get some of the old medium out from the roots. To no avail, I would have damaged the roots if I didn't quit. So I repotted in a larger pot and just put oncidium potting medium around the root mass. Question: am I flirting with rot by not removing the old potting medium ? I couldn't even get into the middle of the root mass where I usually find the old medium and possibly dead roots. I didn't really have a choice, but I am worried. I finally conquered root rot and have healthy chids, but did I do the right thing? Anyone else have a similar dilemma or advise?

I actually had the same problem last year and again this year with my Mtssa. Royal Robe. I did what I could but I suspect it was similar to you-impossible to break up the center of the root mass and remove media. Last year it was pretty big so I ended up dividing it in two and even tho I hacked through it, I still couldn't really remove much from the root mass. so I just re-potted them in some bark with a bit of moss. The plant never even seemed to notice and continued to grow and give me 9 spikes last fall. It also out grew it's pot so I mostly just plunked it into a wider pot this year. I tried removing media again, but impossible. That was only a few weeks ago, but it seems fine.

Having said that- do it at your own risk as my conditions might be different than yours, but I think its just the way that one grows! I don't keep mine overly wet which may prevent rot problems but I don't let it be dry for long either!

I would remove what you can of the old medium, there's no point destroying the roots just to get all of it out. So I do like Silken. I remove the bits that easily come off, and plunk the entire thing into a new pot. The new bulbs will put out roots that will colonize that space. Some years down the road when my plant gets really large I'll rip it into 2 instead of getting yet a bigger pot.

I've repotted several oncidiums exactly the same way that you described and I've always had good results. If you want to keep the plant growing into a large specimen I don't think you have any other choice than the way you did it. If you're concerned about root rot in the center you can treat it with 1 teaspoon per gallon of Physan 20, but it will probably be fine without treating it. The oncidium in this picture was repotted just like you described for the last two repots over about 4 years. Good luck.

https://picasaweb.google.com/1043303...02476220290626

Wow, what a great looking Onc!!! Those spikes are so graceful, now I NEED one of these!

That has already been added to my wish list after seeing it in it's own thread tucker85!

I've said it before
 

and it does work, so don't knock it until you try it.
Cut 1/3 of the root mass off and then repot into fresh media, the roots regenerate very quickly. You probably damage the roots more by trying to remove the old media anyway.

I agree with 'Orchidsarefun', cutting a third of the roots off will work fine. The plant will recover very quickly and grow new roots.

Wow - glad I read this thread! I alway work hard to get all the old media (tho will leave bits the roots refuse to let go of), and recently I know I damaged a lot of roots doing this. And last year I needed to pot up a couple of Onc alliance, both in chc which wasn't that old, so at that time I plunked the whole thing into a bigger pot, and filled in around. Both those plants already need bigger pots again :yikes: or dividing. Good to know I don't need to stress so much over getting into the mass of roots quite as aggressively as I have been.

I did have one last year, no amount of anything I did helped me break up a big mass of roots, and the roots were starting to suffer from my working on it, but it aside for a day, work at it again, etc over a few days, so I finally gave up and plopped it into a pot, and it's been doing well.

Thanks for the replies--I feel much better now about the repot. I think I will probably have to make 2 plants next time; I just put it in a 12" mesh pot. Interesting idea about trimming the roots, I assume the bottom part? I don't know if I would have the courage to do it though.

Tucker, that is a fantastic Onc.!