Looks like over-watering. Try letting the soil dry down more before watering (use a tell?). Also, a high level of dissolved solids (as in fertilizer salts) in the soil solution can inhibit water uptake, so be sure to flush the soil when you water.

I'm pretty sure you are wary of letting the pot sit in water that collects in the cache pot, but if not, that should be avoided as the salts will have a pathway back into the soil.

Tip/Trick: After you water, tipping your pots at a steep angle until they stop draining removes an extra measure of excess water (compare B to A below),

as does using a wick to help drain excess water (compare E to A above).

Newton's First Law of Motion

For conventional container culture, it's a given that saturated/partially saturated media rob roots of the oxygen they need to function normally and efficiently. At best, soil saturation robs your plants of immense measure of potential in areas like growth, appearance, yields, ….. At worst, plants unable to cope with the strain of drought stress caused by saturated media will succumb to it. This isn't a 'scare tactic, it's a very simple and straightforward observation that will be difficult to disagree with a straight face.

Newton's First Law of Motion states that an object will remain either at rest, or in motion at a uniform rate and in a straight line unless acted upon by an external offsetting force. In this case, we will designate the 'object' as excess water in your potting medium. At risk of my being redundant, the 'law' can be seen as a simple statement about inertia, that objects will remain in motion and in a straight line unless a force acts to change the motion. To put the law to work for you/your plantings, you should water to beyond the point of total soil saturation - so the medium has been completely saturated and at least 15-20% of the water you have applied has exited the pot. Unless your soil is purposefully constructed to eliminate all/nearly all excess water, it's extremely probable, when the pot has stopped draining, there will be too much water in the potting medium for the plants' liking.

To eliminate this excess water: immediately after a thorough watering, hold the pot in one hand over the sink, lawn, or over-sleeping significant other and move it downward, then sharply reverse the direction to upward. You'll immediately note that a good measure of 'excess' water will “continue downward in a straight line” and exit the drain hole. The sharper the reversal of direction, the more water exits the drain hole. When you have repeated the exercise until water no longer exits the drain hole on the reversal of direction, you will have eliminated all excess water and your plants will regard you with a newfound sense of awe.

Al

all plants shed the oldest leaves.. its usually seasonal.. and annual ...

i cant quite tell how long youve had this plant... so there might be stresses of moving locations.. light changes... watering changes.. etc ...

soo.... study leaf age.. just remove oldest.. usually lowest or outer most.. and see if that doesnt make it look better ..

also note the newest leaf or two;.. those are what is telling you current situation.. rather than some stress that might have happened weeks or months ago ...

ken

Thank you, Al and Ken. I've had the plant 1 month and this just began. The nursery had these under a sun-filtering carp. I have it on a console in front of a full-wall open window that leads to a balcony with overhead roof, where It receives lots of light but no direct sunlight.

I water the plant weekly, when the surface soil is completely dry to an inch and have not yet applied any form of fertilizers. I did water in a tsp of meal frass as a top dressing 1x when I brought it home. When watering, I do flush the pot to runoff and allow it to drain in the sink. I also do tip my pots to remove any stagnant water. Note I live near the beach in a tropical climate with extremely high heat and humidity.

I have other prayer plants and posted to learn more about the needs of this plant in particular. Not only are the leaves browning in spots, this past week it has not been lifting or 'praying' when the sun begins to go down. Until now it was doing so. This tells me it's in distress.

Two things come to mind. First, I have a tendency to leave new plants in their original pot/medium the 1st month or 2 as they acclimate to their new environment. Perhaps it's time to change the soil to inspect the root system and make sure it's not trapped in one of those horrid 'grow plugs'. Second, I haven't been able to collect rain water lately for my indoor plants and have been using tap water. All are doing well except this one. Perhaps this plant is particularly sensitive and can only tolerate rain water.

M - as dedicated as you are to ensuring your plants are healthy, you might want to consider purchasing a small R/O water filtration system. I have a 5-stage system that can produce about 75 gallons of R/O water per day, and systems that produce 100, 150, or 200 gallons per day. The 75 G/D system is more than enough to filter water for all our drinking and plant needs. I paid about $200 for mine about 10 years ago, and it's currently about $280. It produces water with 0 ppm dissolved solids, so almost all intents/purposes, it's the equal of distilled water and should have a lower level of dissolved solids than rain. See Here

The systems are very easy/quick to install and require only simple tools.

Al