For her senior thesis at New College of Florida, Charlene (Charlie) Lenger set up a plant leasing business and wrote about her experience. The project was so successful that she launched Tropex Plant Sales in 1981, three months after her graduation. Sarasota-based Tropex today has 64 employees at seven locations, annual revenues of about $3.5 million and 1,100 customers. “We are the 14th-largest plant leasing company in the U.S. and Canada,” says Lenger, 52.

Describe Tropex. We are interior landscapers. We provide interior foliage plants and potted flowers for commercial businesses and high-end residences. We also do exterior plants at entrances and artificial Christmas trees and Christmas decorating.

Secret of your success? I’ve worked 80 hours a week for more than 30 years.

What’s special about Tropex? We have a barcode system to keep track of everything and a quality control system for the plants. We practice open book management so all our employees know what salaries are paid, what customers pay us and what profits we make. And, unlike other plant companies, we have customer service managers who are responsible for keeping our customers happy.

The easiest part of your job? Doing the design or the redesign. I was designing Barbie clothes when I was 6 years old. Now I use plants to help create and define space.

Toughest? When a client decides not to renew. It feels like we’ve been fired, whether it is because they don’t have the money to stay with us or because they are closing. In either case, it hurts because we are losing a relationship.

How’s business? We lost $1 million in the recession. We were a $4.5 million company, but now we are down to [annual revenues of] $3.5 million. Some of our customers went out of business and others fine-tuned and reduced the amount of plant leasing. I think we have touched bottom and things are on their way up.

Goal not achieved? To be a statewide company. We now cover about four-fifths of Florida population-wise and about three-fifths geographically, with administrative offices in Sarasota and locations in Fort Myers, Naples, Miami, Palm Beach, Orlando and Tampa. I expect to be statewide in about nine years.

Favorite business book? Getting Things Done by David Allen [also a New College alum]. He is the world’s leading expert on productivity.

What do people not know about you? I haven’t watched television since 1976. That discipline gives me time for a bunch of new opportunities.