I've noticed that when the new growth is a few generations away from the dormant pseudobulbs they start to sprout from dormant eyes. My thinking is that when the old pseudobulbs get too far away to feed the new growth the energy is diverted to the dormant eyes. I guess the same thing happens when you cut the rhizome.

I have had some luck using keiki paste on dormant eyes to get multiple growths but I've only used it on the previous years growth. Another thing I have noticed is that the older the pseudobulb is, the smaller the growth is so you might get a plant that is seedling size on one side and blooming size on the other.

James

Yes you can cut the rhizome but make sure you leave several pbulbs on each side. Slip a piece of plastic between the cut section to make sure it doesn't repair itself.

I do this when I want to divide a Catt the next time it starts growing. If it is big enough I've made two cuts to get three sections for divisions that all have active growing pbulbs. For me it is easier to get new growth this way than sticking the pbulbs in a pot and hope it gets additional active growing points.

Brooke

I have heard it called 'In-house Division'. Works very well. I never put plastic separating the cut and have never seen it repair itself.

The real advantage is when you make a division that is small enough to be iffy. Example would be a Coelogyne where I can just split one or two bulbs from the main plant. With a pair of scissors or a razor blade I'll cut the rhyzome. The split section is now on its own but the root system has not been disturbed and the new plant has a better chance. One year later, if a healthy new growth has formed, you will be able to remove a much stronger and healthier plant.

Another example is a 'Climber'. Some of the Maxillarias I have are typical. 3" between pbulbs as the thing climbs up a long branch makes for a long tall plant. After a while I'll cut the plant into 2, sometimes even 3 sections but leave it in place. New growth will appear from the top of each cut section making for a fuller look. When the thing gets too tall, the other thing one can do is turn the mount around, stand the plant on it's head. It will then climb over itself in the new direction.

Nick

Jane, I think the partial separation thing relates more to the vandaceous type of orchid.
Nick, thanks for the tip re. climbers, I'm going to try it on an out of control Bulbophyllum.

Thanks Brooke, I'm going to give it a try. I have an old C. gaskelliana which followed us through our many moves. I have had it for 6 years and it must have 20+ bulbs. Flowers every Spring and holds sentimental value to me as it was given by an old-timer who passed away two years ago. I have neglected it terribly and it has suffered. I'm trying to rehab it. Lots of sun burn.

It is a large, rangy plant but quite robust making growths from each new pbulb. But I would like to stimulate some old, leafless pbulbs and see if I can force some growth on the other side. I'm glad I checked before dividing. I thought I could just cut between each bulb. So I'll leave three bulbs to a division, except I will not divide. I'll cut and see what happens.

Plant just started new growths so this would be the best time to cut?

Many of the older bulbs are leafless. Would it still work on those?

I'll give it a shot. Its either that or I'll just divide and possibly try to get something from the old back bulbs.

Arthur, I remember a discussion about this a few years back. This plant would be a good guinea pig.

Jane

Jane this would be the perfect time to try it. It would probably work on the leafless pbulbs if the secondary growing points are still intact.

Brooke

I have a friend who has been growing mostly Catts and Laelias for 35 years. He has many of them and they get big. He trims and repots them periodically. Having lost all interest in making new plants he hands me a box of catt cuttings now and then. Some have tags others do not.

I hate throwing away live orchids and most of his stuff is nice so I give them a chance. I have 3 daughters and a daughter in law who love to decorate their homes with blooming catts so even though my interests are with other genera, I will grow them for my kids.

Some are leafless cuttings of 2, 3, or more pbulbs, others have leaves. Other than the ones with healthy, green, leaved pbulbs, which will obviously grow, I have not been able to determine which of the others will grow and which will not. I do not pot them, mount them or do anything else other than lay them on a shady spot on the bench and water them along with the others. Within weeks/months/years (choose one), some will initiate at which point I'll mount or pot them. The rest just lie there in a heap requiring no care or time, once a while I look them over to see if any new shoots have appeared.

Some of the most hopeless looking ones have sprouted, other apparently strong ones with so called 'good eyes' just slowly fade away. As I said earlier, I have not been able to predict which will grow and which will not, watching them for a couple of years will do it.

Nick

Nick, thanks for the cute story. Your daughters and granddaughters are lucky to have you. I have had the same experience with Dendrobiums. I have rooted broken stems and some stems I cut myself. I throw them somewhere and forget them. Surprisingly, some will sprout, no roots but some growth. It takes a long time and I always kick myself for starting them.

Thanks, Brook I'll give it a try this weekend. Spring comes early in Florida. Many plants are acting as if it were Spring and I need to repot many. I'm not repotting the gaskelliana yet. It sends out growths before roots. I'll wait for some roots on that one, but will try cutting some of the back bulbs.

I'll post back any results.

Thanks again,
Jane