Over the years I've accepted that putting orchids (or any plant) outdoors exposed to the elements is going to allow weed seeds to get into the pots. It really isn't that bad, but this is a new one on me! Growing from under a little piece of the dead remains of an old leaf on a Vanda.
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Be who you are and say what you think. Those who matter don't mind and those who mind don't matter.
Well, weeds will be weeds...taking advantage of any opportunity they can find. I've had one Hell of a time with weeds in my pots (And the landscape beds!) this year.
I've picked up some interesting plants arriving in orchid pots. None has been a big problem, and I kind of like the little white melastome (?) that blooms all the time. I did remove a fern to its own pot.
__________________ May the bridges I've burned light my way.