Chlorophilia: from the Greek khlōros, meaning green, and philia, meaning loving; thus, loving all things green and growing.
Now, that sounds straightforward enough and many of us would willingly admit to having chlorophilia but a word of caution. I’ve just been reading on the Wiki Knowledge Dump blog (the place where rejected Wikipedia articles often get resurrected) that the word (which does not appear in standard dictionaries) was ‘invented’ in 2004 to describe a physical or sexual attraction to plants. Tree-huggers, take note!