Brown aerial root tips on Brassavola

[Roberta]

As long as you have all those new roots, you're fine. Older roots do just eventually stop growing. If the environment is very humid, they can get really long, but that just isn't practical in the house. Those new ones look great, the plant will have plenty of root surface to keep itself hydrated. As for urea, much of what you hear about how bad it is is baloney....In nature orchids have to break down nitrogen-containing compounds, so they must have the bacteria in their roots to accomplish that. And they really don't need much fertilizer at all. Yours is quite dilute, and that is excellent. One thought... the fertilizer that you're using has a high middle number - phosphorus, which lowers the pH, necessary if you are using tap water that tends to be alkaline. In pure water, it may be making the solution too acidic (as well as not providing calcium and magnesium). You could just mix some tap water in to the "soup" when you fertilize. You might invest in an inexpensive pH meter. Aim for a pH of around 6.

[j_orchids]

Originally Posted by Roberta

As long as you have all those new roots, you're fine. Older roots do just eventually stop growing. If the environment is very humid, they can get really long, but that just isn't practical in the house. Those new ones look great, the plant will have plenty of root surface to keep itself hydrated. As for urea, much of what you hear about how bad it is is baloney....In nature orchids have to break down nitrogen-containing compounds, so they must have the bacteria in their roots to accomplish that. And they really don't need much fertilizer at all. Yours is quite dilute, and that is excellent. One thought... the fertilizer that you're using has a high middle number - phosphorus, which lowers the pH, necessary if you are using tap water that tends to be alkaline. In pure water, it may be making the solution too acidic (as well as not providing calcium and magnesium). You could just mix some tap water in to the "soup" when you fertilize. You might invest in an inexpensive pH meter. Aim for a pH of around 6.

This is all great info! Thank you! I have been using the fert. in distilled water, but it contains no Cal or Mag. I do have a cheap pH meter, but I'm not sure it's working.

So the deal with urea is that it doesn't hurt the plant - it just might not be available for the plant to use? If I'm just using the fert. to mist the roots and then letting the plant dry, might that lead to a harmful buildup of "urea salts" or something that go unused. Maybe I am over thinking this.

This I know about my water: TDS was 52ppm this month as reported by my utility, but they don't break down the constituents. Fluoride is 0.72ppm. I read that fluoride can harm plants. That's why I switched to using distilled water. Should I just go back to using filtered tap water with the fert. that I have, assuming that the urea and fluoride are no big deal and the 52ppm TDS provides enough Cal and Mag to keep the plants happy (my filter does not remove TDS)?

Oh, also, my utility also reported pH 8.5 for my water source this month.

~Jon