I have a Phalaenopsis orchid whose leaves have been turning yellow for about 2 months now. It sits on a shelf near the window, but it doesn't get direct sunlight. I water it once a week, letting it dry out a bit between waterings. Is it really a lack of light, or am I watering it wrong?
It's not necessarily one or the other - it could be both throwing her off. Phalaenopsis like indirect light but they need quite a bit of it, and near a window without direct sun sometimes it really is too dim, especially if it's an interior room. But weekly watering is way too much - these orchids prefer to dry out well between waterings, like every 2 weeks, and they get root rot super easily if the substrate stays too wet. I'd try moving her to a spot with more light (no direct rays of course) and space out the watering a lot, really let it dry for a few days before watering again.
Phalaenopsis really does need a lot of indirect light, so move it closer to the window or get it out of a dark spot if that's where it is. Before you mess with the watering, try that for like 3-4 weeks and see if it improves, because sometimes we want to water when really it's just a lack of light.
One tip that works: stick your hand inside the pot, down in the middle of the soil. If there's still moisture there, wait a few more days before watering. Phalaenopsis can get pretty dry between waterings, and you end up drowning it without realizing.
Don't mess with everything at once, because then you won't figure out what's actually causing the problem. Weekly watering might be fine, but Phalaenopsis orchids are pretty picky about light - they need plenty of indirect brightness, and near a window without direct sun sometimes ends up not being enough depending on which way it faces and how much light actually gets there. Try increasing light exposure (moving it closer to the window or to a brighter spot) and leave it like that for a few weeks before you change your watering routine, because better lighting already makes a huge difference in leaf yellowing.
Most of the time it's actually overwatering. Watering once a week is way too much for a Phalaenopsis orchid, especially if the substrate (that tree bark stuff) isn't draining well. These orchids prefer to stay almost dry between waterings - the ideal is to water only when the root turns light grey and is no longer dark green.
That said, light matters quite a bit too. Near a window with no direct sun might be borderline - ideally it would get like 2-3 hours of weak sunlight or be in a really bright spot all day. But before you move it around (which stresses it out too), try changing your watering schedule first. Let the substrate dry out completely, switch to watering every 10-12 days instead of weekly, and keep an eye on the roots if you can. Yellow leaves caused by overwatering won't recover, but new ones will come in green if you fix the problem at the source.
What nobody else mentioned: if the roots are rotting (they get soft and brown), you need to repot it with fresh substrate. That's the biggest trap here.
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