For over two decades, Arentz Landscape Architects has developed a consistent body of enduring and award-winning work. We are a boutique firm with regional offices in Washington, DC, Orlean, VA and Rochester, NY. Focusing on residential and select institutional design, we are committed to consistent design quality, process and implementation. We emphasize lifelong stewardship of the gardens that we create and the relationships that we develop.

We approach design holistically and collaboratively. ALA is typically an integral component of interdisciplinary teams of architects, interior designers, civil, structural, and geotechnical engineers, arborists, artists and sculptors. We carefully study each site and its regional context and environment, identifying unique site qualities and ecosystems. Cultural and historical fabric often control or greatly influence our responses to site development. We synthesize and reduce design to its simplest and freshest expression, connecting our work to the architecture that we help to site. Our work aims to blur the lines between the built and natural environments and indoor outdoor relationships.


Richard Arentz's photo

Richard Arentz

Michael J. Rossetti's photo

Michael J. Rossetti

Patrick Carter's photo

Patrick C. Carter

Andrew Seifarth's photo

Andrew Seifarth

Joseph Sampsell's photo

Joseph Sampsell

Hannah Gomez' photo

Hannah Gomez

Sandi Olsen's photo

Sandi Olsen

Richard Arentz photo

“My goal is to find the most fitted relationship to our clients and the landscapes that they choose to live in.”

Richard carries his design and observation skills forward as lead designer and Principal at Arentz.

Richard’s agrarian roots formed his connection to the landscape at a very early age. He observes, “You understand the seasons, the impacts of weather and the interconnectedness of man to nature, growing up on a farm”. He was given the freedom to explore, study and sketch the natural and cultivated landscape. His skills of observation were further enhanced by opportunities to work in 14 different countries, working on environmental, cultural, historical and economic issues of landscape. After graduating from the Pennsylvania State University with a B. S. in Landscape Architecture, his first day of work was in Heidelberg, Germany. This first experience lead to other firms and opportunities with incredible mentors. Projects ranged from resort development in Tunisia, to NATO facilities in Iceland, Embassies in Uganda and Peru, and spending a year living and working on a new government center in Tokyo, Japan. He is currently working on multi-family housing projects in Accra, Ghana.

Richard’s work is frequently published and has been recognized with many awards from the Potomac Chapter of ASLA. Richard received the 2014 Distinguished Alumni Award from the Pennsylvania State University, College of Arts and Architecture. He has lectured at Penn State and Garden Clubs through out the metropolitan area and in England.

Michael J. Rossetti's photo

Michael is a native New Yorker and began practicing Landscape Architecture in Upstate New York in 1998. He joined Arentz Landscape Architects in 2003 and worked in the Washington, DC and Virginia offices for over a decade. In that time Michael served a breadth of roles on residential projects in Washington, DC, Virginia, Maryland, New York, Nevada, Idaho, Jamaica and Florida. He now lives in New York and in 2017 introduced Arentz Landscape Architects to Rochester, NY.

Michael is a licensed Landscape Architect in New York, Virginia, and Maryland. He has a Bachelor’s of Landscape Architecture from Penn State University and was awarded the Merit for Excellence in the Study of Landscape Architecture from the ASLA in 2003. He is also a two-time winner of the Penn State School of Arts and Architecture Medal for Creative Achievement.

Patrick Carter's photo

Born and raised in the Washington DC metropolitan area, Patrick knew from an early age he wanted to "do architecture." He completed his B.S. in Architecture and Masters of Architecture from The Catholic University of America in Washington, DC. Through university and his career, Patrick has focused on high-end and highly detailed custom residential architecture and design in the DC Metro area and around the world.

Throughout Patrick’s education and early professional career, his passion for the found/worked/re-worked landscape led him to meet Richard Arentz and ultimately join Arentz Landscape Architects in 2006. Working at Arentz, Patrick is able to fulfill his ideal, collaborative & holistic approach to residential and boutique commercial projects; seamlessly integrating landscape and architecture.

In his free time, Patrick enjoys traveling, boating on the Chesapeake, riding his motorcycle, working on classic cars and skiing. Patrick holds architecture licenses in DC, Virginia, Maryland, West Virginia and New Mexico. He is also a member of the AIA & NCARB.

Joseph Sampsell's photo

Joe earned his Bachelors of Science degree in Landscape Architecture from Virginia Polytechnic Institute in 2007. While there he earned an ASLA Merit Award for the body of his undergraduate work. Joe joined the Arentz team in 2013. He brings a diverse background of commercial, residential and institutional experience from his time in architecture and civil engineering offices. His work since joining the firm includes senior project management and design for Virginia based projects, Mount Prospect, Old Rag View, and his first significant international project with the Ayi – Mensah Park project in Accra, Ghana. Joe’s interest in landscape design is grounded in the desire to foster personal connections to place through the expression of materials, plants and seasonality. He is licensed in Virginia and Maryland.

Hannah Gomez's photo

Hannah Gomez

Sandi Olsen's photo

Sandi joined Arentz Landscape Architects in January 2016. Previous, Sandi worked in the accounting field in many different industries including hospitality, nonprofit, screen printing and airplane manufacturing.  She started her career in the corporate world at Southland Corporation, but found she liked working with small businesses owners because of the one on one interaction. She has her Associates degree in Computer Science from Northern Virginia Community College.

Giving back to her community has always been important to Sandi. She feels volunteering is her civic duty, and has been involved with both Girl & Boy Scouts, Salvation Army and Habitat for Humanity.

Sandi has two grown children who are out of the nest but live in the Northern Virginia area. Her favorite hobby is to travel and experience new places.

Andrew Seifarth's photo

Andrew Seifarth


8014 Charnick Rd.
Marshall, VA 20115
Phone: 540.341.4330
Washington, DC
1612 20th Street, NW
Suite 400
Washington, DC 20009
Phone: 202.537.8020
New York
40 Kirklees Rd.
Pittsford, NY 14534
Phone: 585.727.7485


Richard Arentz
Home and Design, Designers Choice Award, 2020

Woodside Farm

Merit Award, Potomac/ Maryland Chapter ASLA, 2019

Whitehaven Street

John Russell Pope Award, ICAA Washington Mid- Atlantic, 2019

Sycamore Point

Luxe Magazine, Residential Excellence in Design Award, 2019

Private Georgetown Garden

Honor Award, Potomac / Maryland ASLA 2016

Big Wood Residence
Merit Award, Potomac / Maryland Chapter ASLA, 2015

The Pennsylvania State University Alumni Award 2014
College of Arts and Architecture, Landscape Architecture Department

Belmont Road
Honor Award, Potomac / Maryland Chapter ASLA, 2014

Rock Ford Farm
Merit Award, Potomac / Maryland Chapter ASLA, 2012

A Northwest DC Garden
Merit Award, Potomac / Maryland Chapter ASLA, 2012

Richard Arentz
Home and Design, 100 Top Designers, 2012

Arentz Landscape Architects
Home and Design, Designers Choice Award, Hall of Fame Landscape Designer, 2012

Richard Arentz
Home and Design, 100 Top Designers, 2011

Spring Valley Residence
Landscape Contractors Association, Excellence in Landscape, 2009 Grand Award

Running Cedar
Washington Residential Design Award, 2009

Running Cedar
Residential Architect, 2009

Running Cedar
Merit Award, Potomac / Maryland Chapter ASLA, 2008

Orlean House
Merit Award, Potomac / Maryland Chapter ASLA, 2007

The Cliff
Merit Award, Potomac / Maryland Chapter ASLA, 2005

Trillium House
Merit Award, Potomac / Maryland Chapter ASLA, 2004

Hillmead Road
Honor Award, Potomac / Maryland Chapter ASLA, 2002

Irongate Road
Merit Award, Potomac / Maryland Chapter ASLA, 1998


Feature, Home and Design, 2020 Idea Book
“Designers’ Choice”

Feature, Architectural Digest, June 2019
“A Queen Anne Mansion is Returned to Its Former Glory.”

Feature, Mountain Living, May/ June 2019
“Set In Stone”

Feature/ Cover, Home and Design, Late Spring 2019
“English Garden”

Feature, Home and Design, Spring 2019
“Weathered Beauty”

Garden Design Magazine - Spring 2018

Feature, Washington Life, April 2012
“Green Scene”

Feature, Washington Post, April 2012
“Outside in: A house and landscape are designed in unison, creating a seamless home.”

Honorable Mention, Washingtonian, February 2012
“Landscape Professionals”

Feature, Home and Design, Spring 2011
“Gardens Galore” – Warrenton Garden Club Tour

Feature, Landscape Architecture Magazine, July 2010
“Terra Virginiana”

Feature, Virginia Living Magazine, April 2011
“Full Circle”

Feature/Cover, The Warrenton Lifestyle Magazine, April 2011
“Historic Garden Week”

Feature, Washington Life, April 2011
“Inside Homes: Inside Out, Outside In”

Feature Washingtonian, June 2009
“Design for Living”

Feature/Cover Architecture DC Summer 2009

Feature, Residential Architect, March 2009
“Design Awards”

Feature, DC Modern Luxury, March 2009
“Organic Compound”

Feature, Washington Spaces, Spring 2009
“Garden Destinations”

Feature, Home and Design, Spring 2009
“A Timeless Design”

Feature, Washingtonian, June 2009
”Natural Beauty”

Feature, Washingtonian, April 2009
“Inside 10 Great Homes: In the Country”

Feature, Home and Design, April 2008
“Lodge in the Woods”

Feature, Washingtonian, May 2008

Feature, Chesapeake Home, October 2007
“An older version of new”

Feature, Architectural Digest, November 2007
“Betting the House”

Feature, Land Online, July 2006
“Landscape Architecture in the news”

Feature, Washingtonian, May 2006
“Outdoor Living”

Feature, Washington Spaces, Winter 2004
“Family Structures”

Feature, Penn State Alumni Magazine, April 2005

Feature/Cover, Washington Spaces – Nov 2004
“Family Structure”

Feature/Cover, Washington Post Magazine - April 2003
“Thinking Outside the House”

Feature, Home and Design - Spring 2003
“Among the Ruins”

Feature/Cover, Home and Design - Fall 2002
“A Potomac Garden that Speaks for Itself”

Feature, Washington Post, Home Section - Sep 1998

Feature, Design of Small Spaces - Smith

Feature/Cover, This Old House - Complete Landscaping

Feature, Poolscaping - Erler


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