It was about a man who owns a flower shop and gets together with a business owner who was a horrible drunk due to his divorce. The shop owner also talks to plants and ends up losing his memory of his lover because his special plant died. I'm not sure if this is all correct because it's been a while since I read it and I can't find it again.

well you could try to search with categories like florist
but in this category the only one that seems likely is Manhattan Love Story.

it sounds interesting so I really want to know what it is ^^

Unfortunately, that's not it, and I couldn't find it under the florist category either. I really apppreciate the help though. It's really driving me crazy.

first of all sorry for my bad English but after reading this topic I just coudn't stop myself from replying because I know the feeling of frustration when you can't fint manga you want to reread all too well and additionally manga i think you're referring to is pretty good
So anyway....could it be Kare Otoko ni Izumi that you're looking for?

YES!!! Thank you! Thank you! A million times thank you!