Confused about pseudo bulbs.
 

I have a question about pseudo bulbs. If a spike has been produced and bloomed off a pseudo bulb will that pseudo bulb ever produce a spike/blooms again? And if you have, say an oncidium with several old pseudo bulbs when you go to repot should you separate and toss the old and shriveled pseudo bulbs. In other words do old or back bulbs have any useful function after they have produced flowers. Always been confused about this and afraid to ask.
Pokey.

As long as old pseudobulbs are green, even if they are getting shriveled and have no leaves, they add strength to the plant. If the plant is big and healthy it doesn't really hurt to remove the oldest ones when you repot but you don't have to. Get rid of them if they are clearly dead though as they are just an invitation to rot at that point. Never leave a plant with less than 2 mature growths and a new growth coming if you can avoid it.

After a pseudobulb has bloomed it usually will not get another spike. There are some exceptions though - another reason not to remove a healthy one. A few orchids will rebloom from an old spike too.

PaphMadMan- thanks. Nice explanation and consistent with what little bit I thought I knew about pseudobulbs.

Yes, some orchids (take dendrobium bracteosum for instance) only bloom on old leafless canes and they bloom for years from the same canes.
I have a D. tanii that had only 3 clusters last year, and it will have 10 this year. Not only are the PBs that bloomed last year coming back in, but bulbs that are even older and some newer are also joining the show. Even some that appeared to be totally dead and rotted (lol).

Another useful function of old pseudobulbs is the propagation of new plants from them.

Subrosa. Please elaborate.

Mature pseudobulbs can be removed at repotting time and potted up separately. They will often start new growths.

I would caution you to not just throw away or even divide without a good reason (absolutely certain dead and/or won't fit in pot you're willing to put them in)...because increased size of the clump usually results in much better flowering...than dividing into many small plants.

Psuedobulbs that have already bloomed usually will not bloom again. However, they still act as a glucose and water storage vessel, allowing the plant to store tons of energy and water for blooming. Removing old psuedobulbs will weaken the plant overall - we do not recommend this.

If you do remove an old Psuedobulb, don't throw it away. Pot it up, keep it moist and it may produce a new plant.

Nowhere in this post has anyone said what genus was involved or whether there were leaves on the peudobulbs. Whenever I repot or divide a Cym, I always leave one leafless BB without roots on each division if possible. Any extra firm BBs are potted up if they are from a good plant in hopes of sending out a new growth which eventually will develop into a plant identical to the original plant.

If a Cym has bloomed off a green bulb and there are leaves still on it, there are some grexes which will rebloom on the same bulb. Hybridizers are working on this aspect of Cyms. so saying it will never happen as was once the case, is no longer totally true. Still not the norm, but it can happen with more and more frequency.

could i ask something related? recently i repotted an oncidium jungle monarch immediately after buying and founded that two little pseudobulbs had been previously submerged, so i cut them off.

the question is: if i cut a pseudobulb, what will happen to its relative roots? i really can't distinguish and separate them from the others departing from healthy pseudobulbs.
it makes sense to you to concern about that or honestly is completely non sense? i'm very curious about it

Pseudobulbs are connected via a rhizome. It can be very short, or quite long. Each one is actually a single plant that will have its own bulb, leaves, and root system. As long as they are connected, they will share water, nutrient, and energy resources. Once separated, if the individual is mostly intact, one or more of the "eyes" (meristematic tissue at the base) might start to grow into a new rhizome and growth.

hi, Thank you for sharing your knowledge.
Yours is a really interesting explanation, now all the previous posts are very clear to me and I obviously preserve all the pb as a they posses so great resources and potentials!
bye!

Let me clarify a couple of points, which are alluded to, but not stated clearly:

If you divide a plant:
Cattleyas should be at least 4 mature pseudobulb divisions.
Oncid/Odont hybrids should be at least 3 mature bulbs
Paphiopedilums should be min 1.1/2 fans, provided that they have good roots. Some complex Paphs do not grow roots on new growths till the fan is 2-3 years old; those can only be divided into min 3 fan divisions.

However, do not be in a hurry to divide, A 3 bulb division will bloom, but it will be a small inflorescence. A plant with 6 or 9 bulbs will bloom to it's full potential - often with 2 or even 3 spikes per bulb.