My original plan was to major in marine biology, but then I got sidetracked... I earned a B.A. in American Sign Language / English Interpretation with a minor in Educational Interpreting...
There is a critical shortage of sign language interpreters across the country; you'd have PLENTY of work. I'm currently working full-time as an interpreter in a video relay center, which means I interpret phone calls between people who are Deaf or hard-of-hearing and people who are hearing. I've previously worked full-time as an interpreter in school (middle and high school), a university (interpreting for Deaf students ranging from core classes to Ph.D. level classes), conferences (state, local, national, and international), concerts and plays, doctor's appointments and surgeries, legal proceedings and trials, mental health situations (competency hearings, addiction recovery meetings, therapy sessions, etc.), and other events (I was one of the interpreters for the grand opening of a new national park site commemorating the Little Rock 9 and the integration of Central High School in Little Rock, Arkansas). I've interpreted for public presentations of celebrities.
I've been interpreting for 12 years and I LOVE it.
As far as things that are plant related, obviously botany and biology. There's horticulture, agriculture, landscaping design, etc. I think it just depends on what you want to do.