Our People





Denny Sisson is a Great Falls native, and has been in the landscape business for over 20 years. He launched Sisson Landscapes in 1990 with a mission to provide superlative landscape design and maintenance services to high-end commercial and residential clients throughout the D.C. area. Denny holds a landscape architecture degree from Virginia Tech, and provides design leadership on all our projects. His thoughtful management and positive approach have allowed Sisson to grow to a company of 50+ employees, while still maintaining a friendly and supportive corporate culture.


Roger Clapp is a Great Falls native, with 10+ years in the business, and he joined us in 2011 to work as a Landscape Designer. He earned his Masters degree from George Washington University’s well-regarded landscape design program, and as a student was awarded several notable scholarships. Before he graduated, he was the top winner of the Association of Professional Landscape Designers’ International Student Design Competition. He has earned industry accolades for his professional work, is a contributor to Fine Gardening magazine, and gives back by serving on the board of the APLD’s metro DC chapter.

In his former life Roger worked as an Art Director for a web development company, and is a great help with our website and marketing communications.


Maria Fernandez joined Sisson in 2005, and pulls double duty designing beautiful landscapes as well as managing our landscape maintenance division. Maria has a degree in Horticulture, and is also an ISA certified arborist. Prior to working with Sisson, she ran her own company called Garden Restorations, which specialized in the renovation and re-creation of historic gardens in Georgetown and Old Town Alexandria.


Sam Celich grew up in Vienna, VA., and joined us in 2015 to work as a floral designer and customer service liaison. She has over 10 years experience in the horticultural industry, and is a great help with our container planting services. As a photography major in college, she also has a great eye for composition, and helps us out with our photography-driven social media marketing on sites such as: Houzz, Instagram, Pinterest & Facebook.


As business boomed, Denny needed some help managing the business, and Denny’s folks- Sharon and Hal, stepped in to help hold down the fort at our Sterling production facility. Sharon is in charge of all our administrative functions and bookkeeping. She has had many years of experience managing medical practices and helps to keep all of us organized and efficient. Hal is a retired Navy Captain, and helps out with contract renewals, as well as providing ongoing financial analysis for the business. Both are pleased to be part of Sisson’s success.



We wouldn’t be able to do what we do without the hard work and can-do attitude of our Landscape foremen and work crews, many of whom have been in the business 20+ years. Our guys are landscape professionals who conduct themselves in a polite and respectful fashion, and take pride in their work. Many have gone back to school to obtain additional landscape certifications, and all are legal residents.

We look forward to meeting you!

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