Dendrobium phalaenopsis is struggling!

[AKorchidlover]

I received a dendrobium phalaenopsis as a rescue gift. It’s a noid plant, but I’ve been told it had bright pink flowers. When I received it, had (from left to right) 2 tall canes with leaves, 2 tall canes without leaves, a shriveled cane with a giant shriveled keiki, a shorter cane that was dark brown and shriveled, a short green cane attached to two very small mini canes. Whew!

The dark brown cane looked like it was rotten or infected, so I cut the plant into 3 parts...the 4 tall canes, the keiki, and the smaller cane with the two very, very small growths. The keiki plumped up and has produced an additional 2 smaller but good looking canes with nice roots. The small cane and mini canes have pushed out two additional canes, both smallish but nice looking and green. I’m super pleased with these!

What I can’t figure out is the 4 larger canes. They are driving me crazy. They pushed out some new roots and started a new cane last fall, but the growth got only about an inch long and then turned black and hard. This year, again it added new roots and a started a new growth off of the last aborted growth. But it’s stalled, again! It hasn’t turned black, but it stopped growing.

Any ideas what I am doing wrong? I’m hesitant to repot, but maybe? It’s in bark, a moderately humid area, and gets alaskan summer sun a number of hours a day.

I’d love to see this little one start thriving!

[aliceinwl]

Pictures would help. If the little canes are doing well under the same care regime, it’s possible that there is some kind of infection plaguing the original canes but that’s kind of a wild guess.

[AKorchidlover]

I tried to add some attachments to my original post. The leaf damage in the tall cane was the result of me accidentally crushing it. The older roots are brownish and the new roots are white/green.

Even any basic care/light tips would be great...maybe I’m missing something.

I haven’t been adjusting the ph or using distilled water or anything...should I? Fertilizing half strength with a generic orchid fertilizer every couple weeks.

The new growth has been about this size for a while now...

This is my only dendrobium phalaenopsis (well, the three divisions). I like the idea of them and would be interested in others, but have been really hesitant since I can’t figure out how to keep this one happy!

[estación seca]

There are two common possibilities I can think of.

All Dendrobiums need a very large amount of water when pushing new growths. Their roots also need plenty of air. They make new roots only from the newest growth. If older roots get damaged, like with repotting, they can struggle mightily to take up enough water before a new growth makes new roots.

I think this is your problem. The older canes have much older roots than the younger part of the plant, and are not as good as taking up water. The new shoots from the older canes didn't get enough water and dried up. The medium is appropriate for the plant, but it needed more frequent watering. It is important not to repot most orchids unless they are just beginning new roots, or you can wind up in this situation. However, when you divide and start from older back bulbs, by definition that piece of the plant has no new roots forming. It can be helpful to keep the humidity as high as possible around the plant until new roots start forming with the new growth.

Another possibility is spider mite attack. They are almost microscopic 8-legged arthropods that commonly cause new shoot damage on Dendrobiums that looks just like what you have. Thin-leafed orchids are susceptible to spider mites. Mites are most active when it is warm and dry, like an Alaskan winter with heating. Take a tissue and press it under the leaves, at the stem. Run it to the leaf tip and look for red or brown streaks. If you have mites, you can spray the whole plant with 70% isopropyl alcohol, or a weak dish soap solution, 1 tsp/5ml of soap in a quart/liter of water. This doesn't kill the eggs, so you need to repeat every 4-5 days for 3-4 treatments. Then you need to watch carefully. Spider mites spin very fine silvery webs under the leaves, and leave pits on the undersurface of the leaf from feeding.

I would use the dish soap on your new growths even if you don't find mites on the leaves. They might only be on the shoots.

As to Den phal and hybrids - they like to be warm and moist all year, with high light. Higher humidity is best but most hybrids tolerate typical home environments. They like Cattleya light levels if air circulation is good to remove heat from the leaves. If it gets too cold in winter, or you don't water enough, older stems will drop leaves. But with good care even 3-4 year old stems will carry a full set of leaves.

[AKorchidlover]

I’ll dish soap it up this evening! I haven’t seen any evidence of mites on any other plants or any other parts of this plant, but I am open to trying anything!

When I repotted after splitting everything, it had very, very few good roots. It had to be staked to stay up, so it would make sense that it couldn’t take up enough water for new growth. I’ll be sure to keep it well watered and maybe it’ll get a few more roots and a little bigger this go round. Maybe if it still can’t get one this year, next year the root system will be robust enough...

Thank you for your help!