Thinning versus dividing overgrown healthy plants.

[daddydoall]

Since Orchids bloom on new growth, and pots get very overgrown (good to a point) eventually removing old growth makes sense, but it is always described only in reference to repotting.
Instead of dividing and repotting, if media is in good condition or inorganic (LECA, Rock).
Is it ok or good to:
1. Severe rhizomes on mature plant. I'm told that favors new growths from the old sections, and avoids transplant disruption.
2. Remove some of oldest canes or bulbs to make room for new growths?

It seems if one leaves 3 newest canes on each section, there would be no harm, and new growth may fill back in. If the older sections wither and die, trimming them out is no loss since they would not have bloomed anyways.
I have used this trick on overgrown perennials rather than dig and divide.

How about Cattleya and Oncidium alliance?

[Orchid Whisperer]

If the old canes are dead (brown) go ahead and cut them.

If they are green, they are aiding the plant; cutting them off will not benefit the plant, cut too much and you will weaken the plant.

I do sometimes sever the rhizome and leave the plant potted in order to encourage development of growths from the back bulbs. I plan my cuts so that there are at least 4 canes (pseudobulbs) per division. If you have keiki paste, you can encourage "eyes" to grow into plants with the keiki paste.

[Ray]

My feeling is that doing so would be wasting a resource.

As long as a growth is green, it is still contributing to the overall well-being of the colony, through photosynthesis, water, nutrient, and energy storage, and as long as the roots are viable, nutrient and water uptake, as well. Why get rid of them?

[Cym Ladye]

It may also depend on the genus. Removing leafless Cymbidium pseudobulbs and not removing the roots connected to them then kills the roots leaving a bed of potential rot for the other roots in the pot. This may also apply to other genera. As Ray said, just because a cane or stem has bloomed but is still green, it is still supplying energy to the remaining parts of the plant.

[estación seca]

There are some orchids that bloom from the same old pseudobulbs for multiple years, like Dendrobium speciosum and its hybrids, and some of the dwarf Dens like D. laevifolium.

[Fairorchids]

Overall concensus: Don't. For Catts, min front division should be 4 mature pseudobulbs.

Tertiary consideration, if you ever want the plant judged by the AOS, there can only be one plant in the pot. If you start cutting rhizomes, you disqualify the plant.

[derv88]

I don't understand. So what are we to do with a Catt that has overgrown a 10" pot and is unbalanced to remain upright on its own? Leave it whole and repot it in yet another bigger plant without cutting?

[silken]

Originally Posted by derv88

I don't understand. So what are we to do with a Catt that has overgrown a 10" pot and is unbalanced to remain upright on its own? Leave it whole and repot it in yet another bigger plant without cutting?

If you have the space, I think specimen plants usually put on a much better show of blooms than a plant with 4 or 5 growths. I find I get nice blooms on them but things change once the plant has bloomed for a few years and is larger. However, the reality for hobby growers is that we don't always have room for 12 inch pots for all our favourite orchids. And there is always a friend waiting for a piece or a chance to make a few bucks to help offset hobby expenses on the society sale table. So mine do get divided at re-pot time quite often. I still try and keep the most mature and largest piece for myself

[derv88]

Thanks Silken, turns out my situation may have been a blessing in disguise.

The overgrown catt was in a 6" pot, but had overgrown its container by at least 4". When I dug into it today, I remembered this was a Housermans classic big catt. As I was untangling the dead and alive roots, I remembered that they like to combine more than one plant in a pot so they can fetch a premium. Sure enough, my catt was actually two equally sized plants, each with their own growths.

Without dividing but just a bit of root cleanup, they are now separately in their own 8" pots. There's about a year of room before something else needs to be done.

Thanks for your reply. That's a lot of work.
-Jack

[bil]

Originally Posted by derv88

When I dug into it today, I remembered this was a Housermans classic big catt. As I was untangling the dead and alive roots, I remembered that they like to combine more than one plant in a pot so they can fetch a premium.

I do so hate it when people do that.