Dahlia seedling leaf tips browning
Any ideas here? I have two different types of dahlia and both are doing the same thing. None of my other seedlings (other plants) are getting these brown leaf tips.
They are growing in vermiculite, receive 16 hours of HID lighting and I am keeping the vermiculite moist, but not wet via bottom watering.
The seed leaves got the brown leaf tips first, the next leaf set was clean, but after a few days also developed the brown leaf tips. As can be seen in the photo the 2nd true set of leaves is coming in and is clean so far, but I am not expecting them to remain that way if I don't figure out what's going on.
They haven't been fertilized yet.
Any help is appreciated.