How much success have you had rooting old rootless Cattleya back-bulbs.
 

When repotting, I recently saved some Cattleya violacea, walkeriana, intermedia, luedemaniana, and tigrina back-bulbs (I collect primarily species orchids). An example is the 9-bulb C. violacea photo I've included.

I'm attempting to root these starting with a treatment of 1tbs/gal KLN rooting agent and KelpMax hormones. No pots, 3x/day drench, 50% filtered sun, and day night lows/highs in my greenhouse are around 70F/92F.

Questions: Is it worth the effort? What should I expect for success? What kind of success have you had rooting old partially shriveled rootless back-bulbs like these? What methods?

K-Sci

Disclaimer: Though I've owned several for some time, the back-bulbs were all pretty shot before I owned these plants.

Limited success. Biggest challenge is keeping it from drying out too much while waiting for roots to get to the point of pulling up moisture themselves.

Stand them in a glass of water so the highest bract scar is submerged. Put them in bright shade. Change the water frequently. I've had more luck with this than tbe standard methods.

Dump the KLN and immerse them in KelpMax solution overnight.

In addition to its ability to stimulate root growth, it appears to be good at activating growth in any meristematic tissue present. However, this may be me hopefully extrapolating from the fact that it does multiply branches in actively growing sympodials.

Backbulbs will have dormant eyes.
The better an orchid is hydrated, the more likely the back bulb eyes will start swelling a bit and become more noticeable. If one cuts the backbulbs when they are all shrivelled and dehydrated then it will be far more challenging. I have grown a few backbulbs now and not had any issues but I've also tried with no eyes and nothing is happening there.

I'm also trying with a single bulb that fell off a cattleya last year but as you would expect that will take 3 times longer,
the first picture is from 8 months ago. So maybe 3 more years if it makes it.

They don't rot?
Most of these would require a gallon bucket!
How much light when you do this? I've heard that light levels must be maintained or the plant won't have the energy, but also if you give them strong light it will dehydrate them.
-Keith

---------- Post added at 07:15 AM ---------- Previous post was at 07:08 AM ----------

I've had amazing success with nearly rootless forward bulb divisions using KelpMax. With these back-bulbs I've been following the directions on your site with the exception of bagging and reducing light levels, and also using KLN. Do you think the KLN is counterproductive?

Also, do you think I should bring them indoors where they would be cooler, but get only early morning light and cover them with a bag? I'm thinking I should.

BTW, I just placed an order for 4L of KelpMax this morning.
-Keith

---------- Post added at 07:24 AM ---------- Previous post was at 07:15 AM ----------

It looks like that one has ample root to make it. I'd be lightly misting that partially exposed root 3x/day.

None of these have active eyes, but the forward bulbs had new shoots with active root growth (I won't re-pot unless they are). In the past I would have tossed them out, but having had success over the years with forward bulb divisions, I thought I'd give them a try.

K-Sci

Don't worry K-sci, I've kept it alive for 8 months. It didn't have a single root and if I had stuck it in water it wouldn't have made it. no doubt. It has more roots than one can see, I have my methods... Gets watered twice a week.

Bright shade. I have put them on my kitchen windowsill, facing north by northwest. I'm talking about old rootless back bulbs, not the front division with roots. Perhaps try a tall, narrow vase. The water doesn't need to be deep, just deep enough to cover the rhizome. If you change it frequently they won't rot. Those that won't make it turn yellow eventually. By all means treat it with KelpMax.

Dormant "eyes" are pockets of unactivated meristematic tissue. KLN is a root growth stimulant. You are trying to get the meristematic tissue to grow into vegetation, not roots.

I like the warmth because it tends to accelerate the plants' metabolic rate, and the bag over the plant and pot to trap humidity, slowing the desiccation process that kills.

I think what you are saying is that sufficient new roots won't grow from the rhizomes on these Cattleya, what's needed is for the eyes to grow and put the roots out, so it makes no sense to try to force the roots.

Did I understand you correctly?