Look at all health care related jobs, don't limit yourself and your partner to just the med tech jobs. As a horticultural specialist, she is obviously not afraid of hard work, which many health sector jobs are. For med tech you need a lot of chemistry, which I knew I could never pass, and the work is all in the lab. There's also radiology technologist (must be willing to move big/heavy machines around, wear lead gowns, be into surgery at times, and working all over the hospital at all hours of the day (depending on the shift). There's physical therapy, speech therapy, occupational therapy. There's nursing of all kinds, although many/most states are now starting to require a Bachelor's as entry level. There are many many jobs in the health sector, and it's only going to grow. I would say that nursing and physical/occupational/speech therapy are the most people-intensive, so if working with people isn't quite her thing, rad tech and other such jobs give you people in smaller doses. As a surgery nurse, I get alert people in smaller doses (the rest of the time they're under anesthesia or just waking up) which works for me.
Oh, and if she does want to pursue working as a med tech, she can always become a phlebotomist (the people who draw the blood) and work every other weekend during school which could help financially. If she decides that nursing is her thing, she could work as a unit secretary or as an aide (helping the nurses & LVNs). There are many types of entry-level jobs that could help pay the bills.
She might want to consider testing to see which type of job she could be suited for and then request to shadow someone (a doctor/PA, a nurse, a rad tech, etc) to see if the job is really something that she wants to do. All of these jobs are inside buildings, which may not be her thing since she is probably used to being outside most of the day. Many things for her and you to consider, so good luck.