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I germinated a variety of seeds and I now have the starts inside, under two full small spectrum LED lights. I'm using a couple different mediums. Some are in rock wool. Some are in a store-bought starting medium. Some a combination of both. I'm watering once a week by pouring ~1 inch of water into the tray for an hour (then dumping out). I'm adding an organic kelp fertilizer to the water at the recommended dilution.

I notice almost all my plants have crispy yellowing tips and it doesn't seem isolated to specific types of plants or mediums I'm using. Any ideas what's going on?

More requested details

I'm using two of these full-spectrum LED lights: https://www.lowes.com/pd/GE-1-in-1-Light-White-30-Watt-Single-LED-Grow-Light/1001001640

They're hanging approximately 3 inches above the plants. I turn them off for about 8 hours every night, but occasionally I forget and they get 24-hours of light.

Details about the water: I'm using tap water + a splash of organic kelp fertilizer. Where I live, there's no chlorine in the water.

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It looks like classic tip burn from too much light and heat. Combine with the overall small leaves and this points to either lights too close to the plants, the wrong type of light generating large amounts of heat, or having the lights on for too long. If the plants are exposed to 24 hours of light and heat they have no chance to respire properly; they have plenty of opportunity to do the photosynthesis thing given abundant light so they don't need to grow large leaves to collect enough photo energy, but they have to sleep too. If this does not apply then please edit your question to clarify these points and it will help narrow down what is happening. Some detail on the type of water being used would also be helpful.

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  • "Burn" was my gut instinct too. But I'm confused because I read a lot of advice that suggests putting the lights as close as 1 inch above the leaves. My lights are at least several inches above... – emersonthis Mar 26 at 3:09
  • I just update the question with the specific light and water details you requested. Thanks for your insight. – emersonthis Mar 26 at 3:18
  • I wonder if there was anything suspicious about the details I added about water. Also, do you have any advice about how to help plants heal / recover from tip burn? – emersonthis Apr 1 at 15:03

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