I prefer a white background. Yes, the black makes the bright colours pop, but others, like dark green, disappear. As designers we see the black as elegant, dramatic, romantic - but when you put images on your website they are there so that the customers can get a good look at a product that they might like to buy, not to impress people that always see things from a design perspective. I don't think the black really acheives this. Have a look at other online retailers - I don't think I've ever seen a product shown with a black background. Sure, following the herd isn't always the best move but I think Amazon etc know what they are doing.
I don't have room to have a dedicated area for taking photo's - so like someone said in the other thread I use a white sheet as my backdrop which I fold up again after use and then take the wrinkles out using photoshop. Unfortunately my PS skills are lacking - I use the blur tool to change the background which ends up giving the backdrop a silky look. I know my pics aren't the best, but they do look real and give the impression that I am indeed a real florist.