Why urea free fertilizer?

[boxerfan]

I'm just curious, everything I have read says to use urea free fertilizer, but I don't know why. Anyone know? Lisa

One theory is that urea needs soil in which to break down, Orchids are not grown in soil, they're grown in bark, therefore the urea doesn't break down as quickly. I'm not sure if this is true or not, but there are so many good urea-free fertilizers around that I don't worry about it.

[PhalPal]

Urea-free is recommended for orchids because soil is required for urea-based nitrogen to break down. (like orchids126 stated above) By time the urea has broken down enough to be useable to the plant, it has been flushed out of the pot with regular waterings. Even plants grown in soil will take 12 months to break down the urea-based nitrogen and at best only 2/3's of that is useable.
I use nitrate nitrogen (2/3) and ammoniacal nitrogen (1/3) for ALL my plants, not just orchids for this reason. It is sort of frustrating for beginners when most of the available orchid fertilizers are urea based. I DID notice a big difference when I learned this little fact and switched to a suitable fertilizer. My leaf growth was MUCH greater and healthier.
Some possible brand names to look for that are urea-less: Dyna-Grow, Peters Peat-Lite Special, and Normans Orchids fertilizer. (online) Some farm supply stores also carry a good variety of the less generic types.
I hope this helps you!