Over grown oncidium noid

[MrsRegent]

Hi! I have a seriously over crowded oncidium that I don’t know what to do with. What potting mix should I use? Should I try to divide it? Do I wait until it’s finished flowering? Bonus points to anyone who can ID it

Some back story - I bought this oncidiun at a Safeway about a week ago since it was half off. The fact that it was on sale tells me it had been sitting in the store for about a month, so it’s care over the last few weeks is questionable at best. I’ve kept it in a north facing window and have been watering it to try to rehydrate it a bit.

Thanks!

[Roberta]

Don't divide it. It is not all that big, and it needs the strength of the current pseudobulbs to power the next batch of new growth (which is where flowers will come from)
You can wait until it stops blooming to repot. When you do, a well-drained mix that does hold some water is best - I would use small bark, perhaps with perlite, or maybe some chopped sphagnum. These like to stay on the damp side, so the choice of medium should be based on your watering schedule to accomplish that. Choose a pot that is just a little (maybe 2-3 cm) bigger than the one that it is in. Orchids like to be on the potbound side ("tight shoes"

[MrHappyRotter]

Most of Roberta's advice sounds good, with one caveat.

The optimal time to repot is when the plant has produced new growths and only when those new growths are starting to develop new roots (so it's a little more complex than just waiting until the flowers have dropped).

Furthermore, in temperate regions like North America and under typical indoor growing conditions, it's much better to wait and repot in late winter or early spring (February at the earliest) than it is to repot in the fall when days are getting shorter.

Granted, in regards to repotting, there are other considerations you have to make that might override ideal times -- for instance if you know that the potting mix is rotted or the roots are in bad shape, then sometimes you just have to repot and hope it doesn't set the plant back too much.

It's up to you whether you want to divide it. Typically I hold off on dividing newly acquired plants and let them have 1 - 2 years in my care before, and with these types of crosses, they often self divide after a few years anyway.

One possible mix would be a chunky bark based mix or any standard off the shelf orchid mix. If it has thick roots (though I doubt it does as this type typically doesn't), you can add some bigger bark pieces or some volcanic rock to make it chunkier and keep in mind that it can/should go a tad dry between waterings in the winter. If it has thinner roots (this type usually has thinner roots), then a standard mix is fine, and while you would cut back on water in the winter, you should take care not to let it dry out too much. Basically, though, any mix that is appropriate for epiphytic orchids/plants should work for this type of Oncidium alliance intergeneric hybrid.

As a side note, a north facing window may not provide sufficient light for this type of orchid, particularly during the shortest days of the year. Consider adding artificial lighting and/or moving it to a better exposure. Most oncidium alliance intergeneric hybrids like bright light, up to full morning sun, followed by bright indirect light the rest of the day, ideally getting at least 12 hours of light a day. If they're receiving less light than that, they may go dormant and require dry growing conditions to keep the roots from rotting and to reduce the chance of various infections.

[MrsRegent]

i decided to risk investigating further and managed to wiggle it out of the inner pot with little damage. Roots look ok to me, but it’s in regular terrestrial plant potting mix. I’m thinking if I watch watering levels I should be ok to wait until spring to repot. My house gets dry, around 20-30% humidity, in winter so the extra moisture in the media is probably ok. Agreed?

I’ll see if I can find it some more sun and a light to sit under in the winter - we only get about 8-9 hours of sunlight in dec/Jan

[Roberta]

You should be able to wait to repot, since it will dry out pretty fast.If you see new growth, that would be the time do it, probably will be in a month or two.

[MrHappyRotter]

I'm guessing that's ProMix, which is a soilless potting mix that is appropriate for orchids. It tends to work best for nurseries / commercial growers and tends to be much trickier for home growers.

[MrsRegent]

Ok thank you!

[aliceinwl]

I've had horrible luck with that mix. I would watch the pseudobulbs, if they get more withered despite your best watering efforts: repot. For mine, the withering pseudobulbs was symptomatic of continued root death and the longer I waited to repot, the fewer viable roots were present.