Hold the presses: you said friend. White might be just the thing.
As usual, I'm not your expert. I do know that red is for romance and love. In fact, in Europe it would be very odd not to give a lover red roses, so I am told.
I believe white stands for innocence and purity. Who wants that? I suspect the white for valentines info is incorrect, though it wouldn't be the first time I'm wrong (like maybe they are good for a friend).Yellow is friendship or betrayal. Pink is friendship. Yellow might be best for a friend.
I'm sure any roses you send would be appreciated! If you can go to Costco they have a dozen at high quality and low prices.