humidity high water low after repotting to promote roots?

[nogreenthumbs]

I've seen this sort of recommendation a few places. I just want to make sure that it's valid (I did just read it on the AOS website, who am I to question).

"Keep humidity high and the potting medium dry until new roots form."

"Keep the plant humid, shaded and dry at the roots until new root growth is seen."

I've got a Cattleya that I think I over fertilized. Lc. Chyoong Guu Hsin-I 'Ruby Lip' if it matters. It doesn't have a happy root system. There are some tan roots that are still firm and plump. I bought it last fall, and after the blooms faded, it put out 2 new growths. I've recently repotted it. It's got 2 more new growths coming, but the 2 growths from this past winter are kind of small. It's also got another bump that looks like another new growth and, I assume because the roots aren't great, the p-bulbs are looking a little sad. I'm hoping that some of the new growth starts to put out some new roots.

Basically, I want to know what my best strategy is to preserve this plant and it's new growth and sad roots, and hopefully, put on some new roots too now that I've got it repotted and have learned how not to feed.

Help me save my eager, but slightly sad orchid.

[King_of_orchid_growing:)]

Have you seen my Huntleya wallisii? The humidity is around 92% in the dart frog tank I have it in. Granted it does have good roots inside the basket, and it is a plant that does like quite a bit of moisture, so keeping the media dry doesn't really apply to my Huntleya, but notice that the roots growing in the air are growing like CRAZY!

The roots have grown about 1" in about 2 weeks!!! If the humidity was even 17% - 27% lower, those roots would not grow like that.

You want evidence, that's your evidence. I posted that for a reason. I wanted people to understand the power of controlling humidity for certain orchids.

Your Lc is not the same as a Huntleya, but the basic principle is similar. Jack up that humidity, and you will get the plants to produce roots, especially during growing season.

[estación seca]

First, were all three photos taken at the same time? One photo shows two swelling eyes, which grow to form new growths. I don't see the longer growths on this photo. The other two photos show elongating growths, which could be those two eyes some months later.

The left elongating growth looks healthy, but the one on the right is turning black at the tip. This is often caused by insufficient water, which in turn can be caused by not watering enough, or by having a sick root system. Some people say extra calcium prevents this, but your plant's problem is roots, not calcium. That new growth will probably die back completely. There is a chance only the tip will die, leaving a stunted growth. Fortunately such a stunted growth would probably have growing points, which have the potential to make completely normal growths, with proper care.

Most Cattleyas make new roots as new growths are elongating. Yours doesn't seem to be doing this. It is possible it is one of the ones that makes new roots only after growths mature. Cattleya warsczewiczii is one such plant. This kind of plant needs careful attention not to kill the old roots before growths mature, because the plant will then not be able to take up enough water to support new growths.

It's possible fertilizer burn killed the roots, but more likely is that you overwatered the plant during the cooler winter, and the roots rotted. Or you underwatered as previous new roots were forming, and killed them before they got big enough. Or the plant had poor roots when you bought it. When the roots aren't good, or you don't water a healthy plant enough, new growths are smaller than previous growths.

Cattleyas won't make roots until they decide it's the right time in their growth cycle. Humidity has nothing to do with it. The high humidity is not to induce roots, but to decrease water loss from the leaves until new roots form.

[King_of_orchid_growing:)]

Originally Posted by estación seca

Cattleyas won't make roots until they decide it's the right time in their growth cycle.

They do tend to grow new roots from new shoots during the growing season, which would be right around this time of year.

Originally Posted by estación seca

Humidity has nothing to do with it.

I don't know if I'd be that confident to say such a thing...

Originally Posted by estación seca

The high humidity is not to induce roots, but to decrease water loss from the leaves until new roots form.

Again, I differ slightly in opinion.

Yes, the humidity does help decrease water loss from the leaves until new roots form, but I'd be hesitant to say that it does not help induce root growth. Just my .

[estación seca]

Before I had an evaporative cooler I grew Cattleyas in my sunroom. The relative humidity was 20% - 40%. They made new roots when they were ready. Now that I have an evaporative cooler, and it's always 60% - 80% in there, they still make roots only when they are ready, with new growth, and not out of season.

[King_of_orchid_growing:)]

I am not disputing that they grow roots during this part of the year, because they do.

[nogreenthumbs]

Originally Posted by estación seca

First, were all three photos taken at the same time? One photo shows two swelling eyes, which grow to form new growths. I don't see the longer growths on this photo. The other two photos show elongating growths, which could be those two eyes some months later.

All of the posted photos were taken about 5-10 mins before I posted. The two longer growths are on one side, the shorter growths are on the other side.

The left elongating growth looks healthy, but the one on the right is turning black at the tip.

The coloration of the longer new growth is more of a red/purple/wine color in person, which may not have come out well in the photos, but you have much more experience and knowledge than I do so you're probably correct. The small new growth does however appear to be turning black at the tip. Since I've got 2 growths from the winter and 2 more than are almost 1" long, and the plants got sad roots, I'm not concerned with having another new growth abort. That's probably a good thing in the grand scheme so the plant isn't trying to create the new growth and can maybe direct that energy into root production, wouldn't you say?

This is often caused by insufficient water, which in turn can be caused by not watering enough, or by having a sick root system. Some people say extra calcium prevents this, but your plant's problem is roots, not calcium. That new growth will probably die back completely. There is a chance only the tip will die, leaving a stunted growth. Fortunately such a stunted growth would probably have growing points, which have the potential to make completely normal growths, with proper care.

I tried to do what is recommended by letting the media completely dry between waterings but it was difficult to be certain since the pot was black plastic and the media seemed old when I repotted. I was watering about once a week in an environment the AC running which is usually pretty dry. I was fertilizing (as the seller advised) with balanced Osmocote. I noticed before repotting a buildup of salts on some media at the top of the pot. There may have been a watering (most likely over if anything) but I also think excess fertilizer was a factor.

Most Cattleyas make new roots as new growths are elongating. Yours doesn't seem to be doing this. It is possible it is one of the ones that makes new roots only after growths mature. Cattleya warsczewiczii is one such plant. This kind of plant needs careful attention not to kill the old roots before growths mature, because the plant will then not be able to take up enough water to support new growths.

It's possible fertilizer burn killed the roots, but more likely is that you overwatered the plant during the cooler winter, and the roots rotted. Or you underwatered as previous new roots were forming, and killed them before they got big enough. Or the plant had poor roots when you bought it. When the roots aren't good, or you don't water a healthy plant enough, new growths are smaller than previous growths.

Cattleyas won't make roots until they decide it's the right time in their growth cycle. Humidity has nothing to do with it. The high humidity is not to induce roots, but to decrease water loss from the leaves until new roots form.

I looked at the plant in better light just now. I see what appears to be small bumps very low on the growths from last fall. Hopefully, those will be roots.

Thanks. I guess I'll do what I can and wait and see.

---------- Post added at 07:28 AM ---------- Previous post was at 07:24 AM ----------

Originally Posted by King_of_orchid_growing:)

Have you seen my Huntleya wallisii? The humidity is around 92% in the dart frog tank I have it in. Granted it does have good roots inside the basket, and it is a plant that does like quite a bit of moisture, so keeping the media dry doesn't really apply to my Huntleya, but notice that the roots growing in the air are growing like CRAZY!

The roots have grown about 1" in about 2 weeks!!! If the humidity was even 17% - 27% lower, those roots would not grow like that.

You want evidence, that's your evidence. I posted that for a reason. I wanted people to understand the power of controlling humidity for certain orchids.

Your Lc is not the same as a Huntleya, but the basic principle is similar. Jack up that humidity, and you will get the plants to produce roots, especially during growing season.

These are grown indoors with the AC running most of the time, but the missus does like to open the windows in the evenings so the humidity is not as low as it would normally be when the AC is always running. It has been very humid here lately. I do have them sitting on humidity trays as well. I guess I could try a sphag and bag approach.

---------- Post added at 07:39 AM ---------- Previous post was at 07:28 AM ----------

You guys missed one of the main points of my question.

Should I try to create an artificially humid environment (assuming I can't just put it in a naturally humid one) AND stop watering? Or should I continue to water (allowing to dry between waterings)?

[Ray]

Originally Posted by nogreenthumbs

You guys missed one of the main points of my question.

Should I try to create an artificially humid environment (assuming I can't just put it in a naturally humid one) AND stop watering? Or should I continue to water (allowing to dry between waterings)?

Yes, find. A way to increase the humidity. Short-term, you can just invert a clear plastic bag over the plant and pot to simulate a greenhouse (decrease the direct light exposure a bit, or that could become a "broil-in-bag" situation). Longer-term, find a way to boost it constantly.

Water the plant normally. The roots that grow will be optimized for whatever conditions they develop in, so why stress them by starting them in one, then changing it?

Many of the AOS recommendations appear to be merely documented, long-accepted hearsay, rather than well thought-out information. If you are repotting a plant with severely damaged roots, for example, keeping it dry for a few days will help the wounds dry up to reduce the chance of infection, but it does little to nothing to enhance other root growth. In fact, a brand new root tip, encountering dry medium, may desiccate and die.

[King_of_orchid_growing:)]

I'd do as Ray says.

[nogreenthumbs]

Originally Posted by Ray

Yes, find. A way to increase the humidity. Short-term, you can just invert a clear plastic bag over the plant and pot to simulate a greenhouse (decrease the direct light exposure a bit, or that could become a "broil-in-bag" situation). Longer-term, find a way to boost it constantly.

Water the plant normally. The roots that grow will be optimized for whatever conditions they develop in, so why stress them by starting them in one, then changing it?

Many of the AOS recommendations appear to be merely documented, long-accepted hearsay, rather than well thought-out information. If you are repotting a plant with severely damaged roots, for example, keeping it dry for a few days will help the wounds dry up to reduce the chance of infection, but it does little to nothing to enhance other root growth. In fact, a brand new root tip, encountering dry medium, may desiccate and die.

Ray, thank you. As always, a huge help and fount of knowledge. It seems like you should be able to trust the AOS recommendations, but they just didn't seem "right" to me somehow which is why I asked. It's much to easy to get into the
"You definitely must do it this way."
"But why?"
"Because that the way we've always done it."
rut.

And great tidbit about reducing the amount of light. I'd wondered about that creating too much heat.

Originally Posted by King_of_orchid_growing:)

I'd do as Ray says.

Yeah, that's my tendency.