I'd try lighting the flower's stems and leaves to try and bring it out of the back ground. Might make it less cluttered. Overall, fairly good B&W conversion. Might want to play with the white and black points a bit too.
There's tons of books devoted to B&W digital or film. I'm not sure of how much you've played with B&W, etc so forgive me if I just talk about things you already know, but these are the steps I usually take (and no I'm not even close to the resident expert):
1) I usually start out with picking a particular B&W film to replicate. There's web-sites out there that will tell you the channel mixer levels to approximate dozens of B&W film. I usually step through a bunch until I find one that "generally" fits with my image to give me a starting point and then start to layer.
2) Black and White is all about tonal range and tonal contrast. I try playing with filter layers to give you the best range and contrast. I usually don't stick to a single filter, but I layer many filters and masks to get the best overall result. Generally speaking I start with a filter to give you the best overall contrast--if I shot a close-up of a fern plant, for example, I employ a green filter initially to give me the most constrast in the mostly green image (green filter will let more green light through then red (see color wheel) so red will be dark and green light). I then use gradient tools or whatever else to mask off certain sections and use layers upon layers to get you the best tonal range and contrast.
3) Next step I usually go through is to set the white and black points. This is easily done with either curves or levels. With this you can set true white and true black or you can clip to the right or left to get high-key or low-key images.
4) Determine if I want to add grain. B&W photos can often be improved by adding noise (simulated film grain). Again, there's lots of write-ups of the interweb and places you can download actual film grain for specific types of 35mm film (i.e. Kodak ISO1600)
5)Finally, I think about duo-tones and whether I actuall want "black" and white or blue, green, sepia, a mix, or whatever.
I usually find that B&W images take a lot more post-processing work then color images. I think Ansel Adams said B&W photography is 10% camera 90% dark room.