ever since i got the flower of knowledge the customers all have red dollar signs and frowns, i have lowered the price on every plant and they still are upset with the prices is my flower of knowledge broken?

It depends upon the game difficulty that you have set, which other magic plants that you have, and the prices you were charging for the plants before you got the Plant of Knowledge. There are circumstances where you might temporarily have that problem.

Im finding the same thing. i got the magic plant of knowledge and the magic plant of wealth at the same time, so all the plants are worth more now. plus i am using the more expensive ones to built up my dollars so i can spend them, but i find if you just be patient and wait they will eventuall buy the plants.

sorry for the mistake in posting i didn't even think about it being a spoiler i was just not thinking period! will try not to do that again

I think some of the customers will always frown - You cannot please everyone - as long as the plants sell, don't let them bother you! I have plenty who frown too but I sell all in just a minute or three.

so far when a plant doesn't sell it is because it has a hidden dead leaf i need to prune so i will just ignore the sour faces then and hope that purple roses appear in the game some day!

The purple roses do not appear. AtarahPern created a mod that changes the Tilia to purple roses, though.