Dendrobium Nobile cane discoloration

[Irisha99]

Hi, guys.
So this dendrobium Nobile was potted in some kind of wet soil medium that I posted pictures of here a week ago. It was recommended to repot immediately even though it was blooming. I did repot it but just noticed that one of the canes has this brownish green discoloration. The cane feels softer than the other one next to it. It’s rotting? Do I cut it off? What did I do wrong?
I watered it maybe once since I repotted. It’s standing on a windowsill, radiator is below it. Window is covered by parchment paper, so there is no direct light. Temperature in the room is 69F humidity about 23%. I live in nyc so it’s pretty freezing outside. Suggestions? Thanks

[estación seca]

It might be rotting. There are a lot of things that can cause that. It looks like the bottom of the pseudobulb is still in good shape, so I don't think the roots are going bad.

A Den. nobile type in large chunk bark needs to be watered about every day, especially when in bloom. If you don't water enough they can get very wrinkled and lose pseudobulbs. How often have you been watering since you repotted?

[Irisha99]

Originally Posted by estación seca

It might be rotting. There are a lot of things that can cause that. It looks like the bottom of the pseudobulb is still in good shape, so I don't think the roots are going bad.

A Den. nobile type in large chunk bark needs to be watered about every day, especially when in bloom. If you don't water enough they can get very wrinkled and lose pseudobulbs. How often have you been watering since you repotted?

I read somewhere online that you don’t need to water them frequently in winter time. I watered them thoroughly once since repotting but sprayed medium well about two times

[estación seca]

From the plant's perspective, winter is when it isn't growing nor blooming. They can be manipulated by growers to flower at almost any time, by controlling temperatures. The plant thinks it's spring, so it's blooming and getting ready to grow.

You should be watering it plentifully now, since the plant thinks it's spring. Next year it may flower much later in the year because it will be on a normal schedule, without temperature manipulations by the grower.

[marcmaubert]

Wait, so I have to water it when it blooms? I managed to quickly kill a Dendrobium nobile some years ago, and last year I decided to try again. I haven't watered it since september (but it's fairly close to a humidifier) and it's now in bud. The canes still look really plump, when should I resume watering it? I was going to resume watering until the new growth started, but now I'm confused.

[Roberta]

Originally Posted by marcmaubert

Wait, so I have to water it when it blooms? I managed to quickly kill a Dendrobium nobile some years ago, and last year I decided to try again. I haven't watered it since september (but it's fairly close to a humidifier) and it's now in bud. The canes still look really plump, when should I resume watering it? I was going to resume watering until the new growth started, but now I'm confused.

Now that it has buds, it's starting to wake up, so time to start watering again. New growth should be showing very soon. I have found that a little water while resting is OK, I have killed a few letting them get too dry. Yours seems to have received enough moisture from that humidifier to be happy, and that's great! (Actually, the only harm that I have seen from too much water while resting is that one gets keikis - baby plants - instead of flowers, you seem to have hit the sweet spot. Enjoy those flowers, and be sure to post photos of them when they open!)

[marcmaubert]

Originally Posted by Roberta

Now that it has buds, it's starting to wake up, so time to start watering again. New growth should be showing very soon. I have found that a little water while resting is OK, I have killed a few letting them get too dry. Yours seems to have received enough moisture from that humidifier to be happy, and that's great! (Actually, the only harm that I have seen from too much water while resting is that one gets keikis - baby plants - instead of flowers, you seem to have hit the sweet spot. Enjoy those flowers, and be sure to post photos of them when they open!)

Thank you, Roberta! Should I fertilize too or just water?

[estación seca]

Irisha99s plant is not on a normal schedule. It's been grown in such a way to make it bloom earlier. This is done by exposing the plants to cold night temperatures. Her plant thinks it's March. It needs to be watered. I think it is in trouble because it didn't get enough water when it needed it.

marcmaubert's plant is on a normal schedule, since it's been exposed to normal weather. It is getting ready to flower and make new growth for the year. "Killing a nobile quickly" is usually caused by inadequate watering while it's trying to grow. Nobile type Dens need a lot of water while growing.

I'll say that again. Nobile type Dendrobiums need a lot of water when they're making new growths. They should not dry out during the growing season the way people advise for Cattleyas.

Edit June 15 2020:
[Cultivation information was formerly included on the Yamamato Dendrobiums Web site.] They, or their Japanese branch, probably grew both your plants.

Some points they emphasize: Failure to bloom is caused by too little light, too much fertilizer, giving fertilizer too late in the summer, and by too-high winter temperatures. They say fertilizing too late is the commonest cause of poor blooming.

Excessive keikii formation is caused by giving too much fertilizer, and continuing fertilizer too late in the summer.

Quotes from the Yamamoto Dendrobiums Web site:

The most common cause of poor flowering in this type of Dendrobium is the accumulation of too much nitrogen. For flowering-size plants, use fertilizers with a low percentage of nitrogen. It is important to stop application of any fertilizer in the first part of August. Slow-releasing fertilizers in pellets (e.g., Osmocote) are not good for flowering-size plants.

For differentiation of flower buds, it is important to expose plants to low temperature. Canes (pseudobulbs) which grew from spring through summer and have matured in the fall require approximately one month of low night temperatures.

In the summer, when temperature is high and sunlight is strong, water almost every day to keep the plant from drying out. From about late September, when temperatures begin to fall, gradually reduce watering. When night temperature falls below 50 F (10 C), water only enough to keep the canes from shriveling. Once a week should be enough. When night temperatures fall below 41 F (5 C), keep the plants dry. If you have a greenhouse in which night temperatures in winter can be kept above 59 F (15 C), water lightly whenever the plants are dry.

They recommend starting to fertilize based on winter and spring night temperatures.

The plants should hold leaves on current year's growths for at least two years, and not lose all their leaves each winter. Leaf loss on this years' growths is caused by insufficient watering.

[Roberta]

Originally Posted by marcmaubert

Thank you, Roberta! Should I fertilize too or just water?

You can start fertilizing too. Nobile-type Dens don't need much fertilizer... too much and like water when resting, you'll get keikis instead of flowers. So whatever your fertilizer routine for most of your orchids, you can cut it in half or one quarter, and the plant will do fine.

[Irisha99]

Originally Posted by estación seca

Irisha99s plant is not on a normal schedule. It's been grown in such a way to make it bloom earlier. This is done by exposing the plants to cold night temperatures. Her plant thinks it's March. It needs to be watered. I think it is in trouble because it didn't get enough water when it needed it.

marcmaubert's plant is on a normal schedule, since it's been exposed to normal weather. It is getting ready to flower and make new growth for the year. "Killing a nobile quickly" is usually caused by inadequate watering while it's trying to grow. Nobile type Dens need a lot of water while growing.

I'll say that again. Nobile type Dendrobiums need a lot of water when they're making new growths. They should not dry out during the growing season the way people advise for Cattleyas.

Read the cultivation information on the Yamamato Dendrobiums Web site. They, or their Japanese branch, probably grew both your plants.

Yamamoto Dendrobiums Hawaii

Look in the top menu, Caring. Read both sections, General Care and Hints.

Some points they emphasize: Failure to bloom is caused by too little light, too much fertilizer, giving fertilizer too late in the summer, and by too-high winter temperatures. They say fertilizing too late is the commonest cause of poor blooming.

Excessive keikii formation is caused by giving too much fertilizer, and continuing fertilizer too late in the summer.

Quotes from the Yamamoto Dendrobiums Web site:

The most common cause of poor flowering in this type of Dendrobium is the accumulation of too much nitrogen. For flowering-size plants, use fertilizers with a low percentage of nitrogen. It is important to stop application of any fertilizer in the first part of August. Slow-releasing fertilizers in pellets (e.g., Osmocote) are not good for flowering-size plants.

For differentiation of flower buds, it is important to expose plants to low temperature. Canes (pseudobulbs) which grew from spring through summer and have matured in the fall require approximately one month of low night temperatures.

In the summer, when temperature is high and sunlight is strong, water almost every day to keep the plant from drying out. From about late September, when temperatures begin to fall, gradually reduce watering. When night temperature falls below 50 F (10 C), water only enough to keep the canes from shriveling. Once a week should be enough. When night temperatures fall below 41 F (5 C), keep the plants dry. If you have a greenhouse in which night temperatures in winter can be kept above 59 F (15 C), water lightly whenever the plants are dry.

They recommend starting to fertilize based on winter and spring night temperatures.

The plants should hold leaves on current year's growths for at least two years, and not lose all their leaves each winter. Leaf loss on this years' growths is caused by insufficient watering.

Thanks so much for such a thorough answer. I hope I didn’t kill the plant though the sister plant seems ok for now