I've had my phalaenopsis on the windowsill for a month now, watering it once a week. The leaves started turning yellow from the bottom, and the buds that were just forming just fell off. What am I doing wrong?
Most likely it's overwatering. Once a week might be too often, especially if your pot doesn't have drainage holes or the soil dries slowly. Phalaenopsis orchids like their roots to dry out between waterings. Check if the pot feels wet, smell the soil - if it has a musty smell, the roots are rotting, and that explains the yellowing leaves. When roots rot, the plant can't absorb nutrients properly and drops buds as unnecessary.
Try watering less often and more carefully - when the top layer of bark has dried out about an inch or so. It's also important where your orchid is sitting: if there's a heater or air conditioner nearby, the dry air can cause buds to drop too. The windowsill should be bright, but without direct harsh sun at midday, otherwise the leaves will get sunburned.
If the roots are already rotted, you'll need to repot it in fresh bark and cut off the black roots with a sharp knife. After repotting, water even less - roughly once every 10 days, until the plant recovers. Yellow leaves won't turn green again on their own, but new ones should grow healthy if you fix the care routine.
Check if there's water pooling in the saucer after watering - if moisture builds up there, the roots rot, and that's exactly why your leaves are turning yellow. Phalaenopsis needs to be watered once the substrate dries out completely, not on a schedule. A week is just a rough estimate; it all depends on room temperature, air humidity, and how porous the bark medium is where your orchid's growing.
Buds usually drop from stress - either from overwatering, or from sudden temperature swings or drafts. A north-facing windowsill can get cold, or maybe there's an AC unit nearby. Try moving the pot away from the edge of the window frame, and make sure the temperature doesn't drop below 15 - 16 degrees at night.
One more important thing: when you start watering less frequently, the plant might look stressed for the first month, but that's normal - it's recovering. New buds will appear once the root system gets back on track.
# Yellow leaves and falling buds are usually caused by moisture issues, but often it's not just overwatering - it's water sitting stagnant in the substrate. Orchids grow in bark, not soil, and it needs to dry out between waterings. If the saucer is constantly wet or water starts pooling in the pot when you water, the roots suffocate and rot, which is why the leaves turn yellow and buds drop.
First thing - check how you're watering. The best method is to submerge the pot in a bowl of water for a couple of minutes so the bark soaks evenly, then let the water drain completely. After that, the pot should sit somewhere the excess water won't collect in the saucer. And most importantly: don't water on a fixed schedule like once a week. Only water when the bark is completely dry - that could be ten days, it depends on the humidity in your home and the temperature.
Here's a tip: put a small glass of water next to your orchid. As it evaporates, it'll increase the air humidity - the leaves will stop drying out and the buds won't drop. Meanwhile, the substrate itself stays drier, which is perfect for phalaenopsis. If the leaves have already turned very yellow, trim them off - they won't recover anyway, and the plant will just waste energy on them.
My friend got a phalaenopsis, and the exact same thing happened to her - for a month or two she was watering it like a regular houseplant, then the leaves turned yellow and the buds started dropping. Turns out the bark needs much more time to dry out than soil does, and she was also leaving water sitting in the saucer. When she moved the pot to a place where moisture wasn't pooling and started watering less frequently (making sure the bark actually dried out), after a while new leaves came in healthy and it started blooming again. Maybe you should check whether you've got water sitting in your saucer after watering and how quickly your substrate dries?
Drainage holes in the pot are the first thing you need to check, because without them water will definitely stagnate, even if you water carefully. If the holes are there but water is still pooling in the saucer - that's a sign that you're really watering too often. Here's the thing: a lot of people think that since orchids "like moisture," you need to keep them wet all the time, but phalaenopsis actually prefers the cycle of "soak and dry out." Let the substrate dry completely (the bark should become really light), and see what happens with new buds - usually they start appearing again after a couple of weeks.
The main thing is that orchids in bark don't like frequent watering. At my dacha I see how people kill flowers with too much water, and then they're surprised. Once a week for a phalaenopsis is often, especially if it's not very hot in the room. The bark should dry out about five centimeters deep before the next watering - that could be 10 days or two weeks depending on the season.
Check the saucer - if water pools there after watering, that's a problem. The roots become waterlogged and start to rot, and that's when the leaves turn yellow from the bottom, and the buds drop. Make sure the pot drains well, and drain any excess water from the saucer after watering. If the substrate is wet - wait for it to dry, don't rush with watering.
With buds, sometimes they drop from stress - overwatering is stress, but it could also be a draft, or a sudden temperature change. A windowsill is a dangerous place - it gets cold at night and gets direct sun. Try moving it away from the radiator and window if there's a draft there. And don't worry if the first leaves take a while to recover - wait until the substrate dries out properly, and the plant will gradually bounce back.
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