Question
QUESTION: Hi,

I've had a small Dendrobium orchid for around 2 years now, and it's flowered beautifully at least three times.  However, it has never had very many roots, and successive new canes have been thinner than the previous ones, which worries me a bit.  Unfortunately, since I made the mistake of waiting too long to change its potting mix, almost all of the roots rotted about two months ago.

I trimmed the dead roots and replaced the potting mix right away, and have cut back on watering to encourage it to grow roots, but it seems like no new roots nor canes are growing.  The existing canes are getting skinnier and skinner, and one may have died since it's lost all of its leaves.  For a while I was withholding fertilizer since I suspected it was encouraging it to bloom even though the canes and roots didn't look strong enough, but I've started weekly fertilization/watering again.

Is there anything else I can do to help my Dendrobium?  I would also like to know if this is just a 'resting period' or a sickness.

Thank you very much!

ANSWER: Hi Catherine,

The new cane growths being smaller than the older canes was an indication that something bad was happening, probably to the roots as you discovered when you repotted it.  When you repotted it, did you put it back into the same pot?  With few or no roots, it is almost always a good idea to repot into the same size or slightly smaller pot because the potting media remains wet too long due to the few roots not taking up any water, which then may cause the few live roots to rot also.  

With all that said and done, here is something you might try to help encourage some new root growth as spring is when it should be starting a new growth cycle.  Put it in a warm shady location and place the pot on a saucer or tray then put a large plastic bag over it, covering the plant and pot to create a mini-greenhouse environment.  Do not water or feed it for 3 weeks and as it slowly dries out, this may help encourage new root growth.  After 3 weeks, add just a little water to the tray, leave the bag over it.  Do this several times over the next month or two.  

Although your dendrobium sounds like it may be one of the evergreen types, it is not unusual for a few canes to lose their leaves over time.  What would be unusual would be for many of them to lose their leaves in a short time.  Evergreen dendrobiums do have a semi-rest period in winter but you should not stop watering, just reduce it to keep it barely moist in winter.  

Lastly, dendrobiums do not require lots of fertilizer to grow and bloom so go easy on the feeding.  Use about 1/4 the amount suggested on the conatiner when you feed it.  

Hope this helps.

Jim Kawasaki
San Jose, Ca.



---------- FOLLOW-UP ----------

QUESTION: Hi Jim,

Thanks for your informative response last time.

I did repot the orchid back into the same pot. Unfortunately the pot seems to be too small given the very reduced size of its root ball. What you described, with the reduction in roots causing the remaining good roots to rot, sounds a lot like what has happened to my orchid.

I put a bag over the plant as you said, and I checked on it yesterday. The canes are looking a bit more shrunken in than before, and no sign of new roots has appeared, but I'll keep it under the bag for at least a month as you suggested.

I have always fed my orchid with tiny amounts of fertilizer for fear of fertilizer burn, and during the winter I was only giving it water, so I'm glad that I was doing the right thing according to your advice.

Once again, thank you so much!

- Catherine

Answer
Hi Catherine,

If it does not start to grow new roots soon, there is one more thing you can try to encourage it.  Take the dendrobium out of the pot, clean off any media from the roots then put it and a slightly damp paper towel in a plastic bag (ziploc) then close the bag.  This is similar to the bag over the plant and pot but without the pot. Your dendrobium should be starting a growth cycle now and should begin growing new roots along with a few new canes, they should be showing up within a month or less.  Allow the roots to grow to about 2 inches then put it in a pot.  

You were doing the right thing and didn't know it!  You must have intuitively known what to do!!  

Jim Kawasaki
San Jose, Ca.