dividing oncidium alliance - Orchid Board

deathofregret · #1 05-24-2010, 08:06 PM

goodness, i can't seem to get enough of you guys this week! so today i'm repotting an oncidium alliance that's finished flowering - the spike has gone brown and papery.

i removed all the old potting medium to reveal a majority of roots that are dry and papery, with what seems like very few healthy roots. the new growths have healthy baby roots growing at their bases, but they're teeny-tiny. the plant is fairly large. is dividing an option in this situation? if it is, can someone guide me through it? should i be cutting back the papery roots? the leaves are a healthy green color otherwise, maybe slightly too dark from under watering and slightly damaged from the original vendor. (the NOID plant was a gift from my husband. after all these problems, i'm going to stop buying from stores and try to find someone that focuses only on orchids.)

the psuedobulbs on the plant are also crinkled, which makes me think it's not retaining enough moisture and might need to be watered twice during the week after repotting.

anyways, thanks!

- h

WhiteRabbit · #2 05-24-2010, 08:24 PM

I would soak the roots for a bit to make it easier to determine which roots are good.

I'm not sure how big your plant is ? As I see it, I probably wouldn't divide it unless the size is unmanageable for you - like it would be to big for your windowsill if that's where you grow it. If you think you want to divide it - each division should ideally consist of at least 3 older pbulbs plus at least one new growth. That may help you decide if it's divisible.

Older pbulbs do wrinkle a bit - so far your new growth isn't pleated, so I think the watering has been ok. But new media will dry quicker than the older media, for a few weeks, so you may need to water a bit more often initially. But if you don't divide, remember, media in a larger pot will retain moisture longer than in a smaller pot. That's why I always use skewers lol

deathofregret · #3 05-24-2010, 08:26 PM

how do you use the skewers?

how long should i soak the roots for? how will i know which roots are happy? I HAVE SO MANY QUESTIONS, RAAAAAWR!

WhiteRabbit · #4 05-24-2010, 08:46 PM

5-10 minutes should suffice. Any that are firm are good. I can't be sure, but to me it looks like the roots visible in your photos are mostly good - I would suspect there may be dead ones in the center of the mass.
If the roots still feel 'papery' after getting some water, then I suspect they are dead. Sorry - I'm not very good at explaining

deathofregret · #5 05-24-2010, 08:49 PM

no, that's actually a perfect explanation for the roots, thank you! i'll just clip away the dead roots at the center. i figure there have to be some good roots in that system to keep supporting a fairly large plant - four pseudobulbs and two new growths with leaves about a foot and a half to two feet.

okay, so explain this skewer trick to me...

WhiteRabbit · #6 05-24-2010, 09:12 PM

Quote:

Originally Posted by deathofregret

no, that's actually a perfect explanation for the roots, thank you! i'll just clip away the dead roots at the center. i figure there have to be some good roots in that system to keep supporting a fairly large plant - four pseudobulbs and two new growths with leaves about a foot and a half to two feet.

okay, so explain this skewer trick to me...

bamboo skewers like for kabobs - you can get them at the grocery store usually - stick one in the media - if a clay pot it should be placed near the center of the pot, in a plastic pot you can place it a bit further out, but not all the way to the edge. I leave the skewers in the pot all the time, makes it easier for me. The skewer should at least be in the pot for an hour tho to check the moisture. Pull the skewer out - touch it to your cheek or above your upper lip - if it feels damp, or cool, there is moisture in the pot. For Oncidiums I usually water before media is completely dry. So, when the skewer doesn't look WET (tho with a new skewer you may be able to tell by it's appearance that it is damp) anymore, but is just slightly damp and cool feeling. Try to replace skewer into same place you had it so as to not damage roots. If left in the pot all the time, like I do - the skewers do after a bit of time break and need replacing. Fortunately they are very inexpensive! They can also stain from the media - which just means it's harder to tell by looking at them if they are damp, but if you touch to your cheek, you can still tell.

orchidsamore · #7 05-24-2010, 09:54 PM

I find that many beginners in orchids mistake old roots for bad roots. There is nothing bad or rotted about any of the roots in the photos.

Oncidium roots are thinner and appear dryer than other types of orchids. Only new roots will look plump and only for the first few months after they emerge. The other roots are still good.

The plant lives predominately off the pseudobulb. They can live with remarkably little roots.

The easiest way to determine if the roots should be removed is to hold a few between your fingers and pull on them. If they break off easily discard the broken pieces and when they stop breaking re-pot.

Your plant did not look like it even needed re-potting. It will not divide well. You only have three old pseudobulbs and the new growth. Division now will probably lose the next flowering season.

Commercially I divide down to one pseudobulb but I do not recommend that for hobbyist. Oncidium will look much better when they get to 6-8 pseudobulbs and 3-5 spikes. This will never happen if you keep dividing it and up-sizing the pots to fast.

This plant can stay in a 4 inch pot for 2-3 more years. Oncidium do best when they are overflowing all sides of the pot.

deathofregret · #8 05-24-2010, 11:25 PM

thank you very much for the incredibly informative reply!

the roots didn't seem rotted, but they were definitely a different consistency than when i was dealing with repotting a phal, which is why i was unsure. the only reason i was repotting was because the flowering on this plant was done and the spike was browned - do the oncidiums not need repotting after the end of the season?

again, thank you for your help!

WhiteRabbit · #9 05-24-2010, 11:30 PM

Depends how old the media is. When we get new plants, we don't know how old the media is, so it is generally recommended to repot new plants. Since we frequently get new plants while they are in bloom, I, at least, do re-pot when they are finished blooming. Bark should be replaced about every-other year. And whether or not a bigger pot is needed depends on the size of your plant. It's best to give it room for 2 years growth.

deathofregret · #10 05-24-2010, 11:33 PM

well, everything i've read says oncidiums are pretty hearty plants, so i think it will live through a repotting whether it was necessary or not. PLUS, i learned all these interesting things about the root system, so definitely not a complete loss all around.

thanks for the info on the bamboo skewers; it seems like a great way to stay on top of my plants' moisture. i'm going to make that my project for this week!