Backbulbs

[Richard Butt]

Could someone explain what backbulbs are and how one would know to use them to start new plants?

[mayres]

Backbulbs are the older leafless pseudobulbs from an orchid plant. Depending upon the type of orchid the length of time the leaves stay on the plant and associated pseudobulb might be 2-4 years, at which point you end up with a leafless usually oblong (but sometimes rounded) plant structure. This can be separated from the newer part of the plant and placed into a very small pot by itself and in a few months you will hopefully have new growths coming out from one or both sides, that will eventually develop into larger and larger pseudobulbs and leaves. This process is not for the weak at heart - it takes YEARS to grow a plant to blooming size. Good luck - mike

Picture of backbulb I was fortunate enough to get growth on -

[Richard Butt]

Mayres,
Thank you for the information, and for including the picture. I have old pseudobulbs on a cattleya. The pseudobulbs seem to be "drying" as ridges are forming and they are shrinking in size. They still have leaves, so I will wait for those to dry up.
I will attempt to start a plant, so I appreciate your warning about time.
Richard

[Cynthia, Prescott, AZ]

The term 'backbulb' can have several possibilities. The reason we use the word 'back' is because there isn't a recent growth on what you would call a backbulb, so all the bulbs are a few years old. Most backbulbs are 3 or more years old, and I caution you not to start cutting off bulbs without considering that a Cattleya needs 3 to 4 bulbs in a row on the forward section to be able to fully grow to normal maturity. This new growth is the normal pattern of growth for any sympodial, one new growth per year, and with some, 2 growths in succession per year. So, you can expect a Catt backbulb to have bulbs that are 4 or more years old.
.

For Oncidiums and a few other sympodials, 2 strong bulbs would be the minimum to leave on the forward part of the plant when repotting.

Now given the usual pattern of removing backbulbs, they may have leaves and/or they may have roots, or they may have neither, which is probably more usual. I just removed a three bulb back section of my C. maxima, leaving 4 or 5 forward bulbs, and had both leaves and some roots on the backbulb, a very fortunate situation. The backbulb also already has a new growth well on the way, since I cut the rhizome a few months ago, but did not repot. I now have a plant that does not need Sphag & Bag, and will bloom next season or the year after. The reason for the excellent condition of the backbulb is probably because the plant seems to be producing 2 growths per year, so the bulbs, instead of being 6 or more years old, are probably only half that.

One more item of consideration is that there must be living eyes on the backbulb, or you can throw it away, as it will never grow without living eyes. This is difficult to determine on some types of orchids but should be pretty obvious on a Cattleya

[joan gero]

Gee, Cynthia, that just BEGS the next question: what's a living eye?
Thanks much,

[slippery_biscuit]

Darned interesting information here. I was wondering when to whack some bits of the older part of the plants and then I stumbled onto this thread. Now I see there is a method to the madness...

I'll be having a closer, wiser, look at them soon. thanks. jeff

[Tobi]

A living eye is a viable vegetative bud (tiny swelling) at the base of the
pseudobulb which will swell and break into growth acquiring new leaves
and sending out roots.

[joan gero]

Thank you very much, Tobi. I'll look for 'em