Leave them. They serve as an energy reserve. For example, If the plant loses its roots, new growth is generated from the energy stored in these bulbs rather than the roots like they normally would. They are referred to as back bulbs.

You can make divisions of your plants with them. Just make clumps the consist of a few of these bulbs, and new growths will grow from them.

This post was edited by terpguy on Fri, May 2, 14 at 17:44

Thanks Terp. Good to know.

So I can use just the back bulbs to make new plants, or do the clumps have to contain back bulbs and newer bulbs?

General advice for Cymbidiums that might be applicable to Oncidiums is to have the growing lead and counting back from that lead 3 or 4 pseudobulbs in divisions,

Both ways, as I mentioned and as Arthur mentioned. Dividing the lead growths (most recent few bulbs) as Arthur describes is the best way and gets the plant established faster.

Back bulb divisions are the left-overs of the above process. Back bulb division is less ideal as it takes longer to establish. Most people only do it if they divide their plant and don't don't really want to throw out the old growth. They can keep it or trade it away.

This post was edited by terpguy on Fri, May 2, 14 at 20:38