Is this Phal just losing old leaves or is it a problem?

[AEKass]

One of my phals developed 3 yellow leaves in the past week. I'm not sure if it is just shedding old leaves or if there is a problem. I repotted the orchid a few weeks ago after it dropped its flowers (I also cut the stem when it started to brown). I have photos of the yellow leaves and a photo of the roots in the new medium I repotted it in.

As a bit of background, I moved from northern California to Boston over the summer. My orchids are now near a northwest facing window. I water about once a week (depending on how they look) and use sink water.

Are they yellow leaves just dying old ones? Or do I have a bigger problem?

[Roberta]

That's a very chunky medium. And fresh as well. So you likely need to increase watering frequency. Once a week may be been adequate with the old broken down medium, but now the plants dry out MUCH faster. (Which is good!) It may be shedding leaves as an attempt to lose less water. To get a feel for the new watering needs, consider this approach: Water well (like under running water from the sink), let drain, and weigh on a kitchen scale or postal scale. Weight again the next day, etc. When the pot stops losing weight (not much more water to evaporate) it's time to water again. Once you have done this a few times, you'll have a good idea of how often you need to water. (As the weather gets cold and the heater is drying out the air, you may need to evaluate again and possibly increase frequency some more. You can't just go by the calendar, there is no "one size fits all".

[estación seca]

I agree it should probably get more water.

Also, Phals. in warm, humid greenhouses carry more leaves than do those in cooler, dryer homes. Water loss through transpiration is higher in low humidity. The roots may not be able to take up enough water when a plant is moved to a lower humidity environment, and the plant drops leaves.

[Jmoney]

Not sure if you are well-versed with coconut husk. I find they are very water repellent initially (despite soaking) but in a month or two the material will hold water significantly longer than it does now.

[AEKass]

I am not versed in that medium at all! This was not the potting material I was expecting when I ordered it. Thank you for the advice!

---------- Post added at 03:03 PM ---------- Previous post was at 03:01 PM ----------

Thank you Roberta! You have given me great advice over the years and this is no exception. I had been thinking I needed to water less since I moved to a more humid climate. This also was not the potting material I thought I was ordering and it is much chunkier than the previous material.

[AEKass]

As a bit of an update, I've been weighing the plant and it's been 10 days and the weight is still decreasing! So I think I was overwatering. The new environment is also much more humid than CA.

Thanks for the help!

[Ray]

I don't think you're overwatering. The plant is sucking the water and nutrients out of those older leaves because it's simply not getting what it needs.

I can think of two, potentially connected reasons:

You say to repotted it a few weeks ago... Was the potting medium different from this one? If so, it is possible that the existing roots just aren't "up to snuff" for this medium, so you should be encouraging the growth of new roots with warmth and humidity, possibly with a good stimulant.

The plant should not go dry, but the potting medium should remain evenly moist, considering how coarse and airy it is. Whether the root system is "iffy" or not, the plant needs more moisture.

[AEKass]

Hi Ray:

Yes, it's a totally different medium (which I didn't realize). I have the Kelpak stimulant so I can use that. How often should I use it?

[Dimples]

A northwest window is going to have very low light for most of the day, so it’s possible that the plant is shedding leaves it can’t support anymore. It’s likely the change in medium has also impacted the plant, but if it had been getting more light previously, that’s another factor to consider.

[Ray]

Originally Posted by AEKass

Hi Ray:

Yes, it's a totally different medium (which I didn't realize). I have the Kelpak stimulant so I can use that. How often should I use it?

While trying to kick-start it into growth, I'd apply it two or three waterings in a row at 1 tablespoon/gal.