Board of Directors

A new normal at the Gardens: Zoom board meetings!  Left to right, top to bottom are Troyce Fisher, Joni Frederick (office coordinator), Roy Markwardt, Bob Rennebohm, Merlyn Tiedemann, Barb Nicholas, Ciar Carnell, Becke Dorenbush (with Donna Dull on the phone), Andy Johnston, Leigh Trembath, David Burgart, Brenda Winter (bookkeeper), Ann Grochala, Angie Perez (development coordinator), and Linette Heydt.


Troyce Fisher, President 

Troyce has been the president of the Central Gardens Board of Directors for three years now and is grateful for the patience of other board members and volunteers who teach her how to properly weed and dead head! Retired from a 43-year career in educational leadership, besides volunteering at CGNI she also relishes being a grandma, is a member of the newly created State of Iowa Children's Mental Health System board, and enjoys reading, walking, doing random acts of kindness, and savoring a glass of fine red wine.

Becke Dorenbush, Vice-President

Becke has enjoyed bringing friends and family to Central Gardens since its inception. Becke remains active in the Iowa Dental Hygienists’ Association for which she serves as the Corporate Relations Chair. Practicing dental hygiene for 43 years working in Blue Earth, MN, Ames, IA and Jewell, IA, she recently completed a mission trip to Haiti with Zion Lutheran Church, providing oral health care to those in need. She has enjoyed helping with the Gardens’ Plant Sale and Gardening Fair, planting and weeding.

Ann Grochala, Treasurer

Ann is a master gardener who spent most of her career in finance in the Washington DC area and returned to Iowa in retirement. With parents and grandparents who had large vegetable gardens, she developed her love of gardening at a young age. She enjoys sharing her knowledge with young gardeners as a volunteer in the Kids BEE Happy Garden. She also maintains the Plant of the Year garden. Ann became a board member in 2018. Ann lives in Clear Lake.

Donna Dull, Secretary

Donna Dull of Clear Lake, retired after teaching kindergarten for 41 years and then decided to take part in some community activities that she had been unable to join before because of her daily teaching schedule. Vegetable and flower gardening was done on both the maternal and paternal side of her family, so when the idea of a public garden was talked about, she decided to join the project. She has been a member of the group developing our Central Gardens since the very beginning. Her first board position was as historian and then board secretary responsibilities were added. She continues to hold both positions. Peonies from her maternal grandfather's yard and a rosebush from her paternal great-great-great grandmother are important in her own yard. The rosebush is said to have come down the Ohio River and up the Mississippi River by flat boat to Iowa before the Civil War.

Roy Markwardt

I grew up as a third generation avid gardener. Being a farmer was a natural extension for pursuing my love of the land and an appreciation of what it can produce. I am pleased to be able to volunteer and be a part of this valuable asset of North Iowa. After leaving our gardens on the farm and 40 years of accumulation and labor of love, I and my wife Patty wanted to be a part of Central Gardens of North Iowa. I am looking forward to serving on the board and making the gardens a beautiful place for all of North Iowa.

Andy Johnston

Andy lives in Mason City and joined the Board in 2017. He is excited to be a part of an organization tasked with adding beauty and recreational opportunities to North Iowa. Any is a lawyer with the law firm of Heiny, McManigal, Duffy, Stambaugh and Anderson. When not in the office, he enjoys getting his hands dirty. He lives with this wife, Tasha, two dogs, Ollie and Doby , and cat, Gilly.

Barb Nicholas

Barb Nicholas, Clear Lake, is the Gardens “plants manager” and one of the charter board members of Central Gardens. She retired from nursing to devote more than full-time to taking care of the plants in the Gardens. Her eye for aesthetics and knowledge of which plants will prosper where is a big reason the Gardens bloom in such magnificent ways. Chances are you’ll find Barb at the Gardens no matter when you drop in. She scouts for the best buys for purchase of our annuals, oversees where to place them for maximum effect, serves on the design committee, and even unofficially mentors a young gardener from the Gardens neighborhood who “helps” Barb do some of her many tasks.


Bob Rennebohm

Bob Rennebohm is a summer resident of Clear Lake. He joined the Central Gardens Board in 2014. Bob is a Registered Landscape Architect with over 45 years of experience in the design and construction of public spaces, arboreta, recreational facilities, playgrounds, and public and private gardens. Several of his projects have received national awards. As Chairperson of the Central Gardens Design Committee, Bob's goal is to shepherd the continual evolution of the Gardens as one of the premiere public gardens in Iowa.


Linette Heydt

Linette Heydt of Clear Lake connected with Central Gardens soon after her family moved to the area, because their daughter wanted her wedding in a garden. That was in 2008 before there were any buildings on the sight. (Central Gardens has grown more and more beautiful every year since that day!) She became a board member in 2009, and is a volunteer at heart. She especially enjoys helping with the fundraising events at the Gardens. With her schedule she’s not able to do a lot of the hands-on work in the gardens but is so appreciative and amazed at the many devoted volunteers who help make the gardens so beautiful.


Leigh Trembath

Leigh’s passion for nature, children and volunteering came from her roots, with both parents being educators and involved community members.  An active volunteer for Central Gardens since 2006, she rejoins the board in 2019. She also serves on the Clear Lake Farmers Market board and Clear Lake Local Foods Team. Leigh’s involvement at Central Gardens has focused on education, developing Fresh on Fridays and building the kids Bee Happy Garden. She is grateful for the support received to create an area where  kids can connect to plants, pollinators and the food we eat.  When not gardening, Eva & Oscar (Bernedoodles) escort her to the dog park regularly. Leigh also enjoys  photography, traveling and most of all spending time with family!


Gary Nyhus

Gary Nyhus has lived in Clear Lake for forty years with his wife Sandy, a retired French teacher. Gary and Sandy have two sons. Son Chad lives in Mason City with his wife Rebecca and son, Finley. Their son Jason lives in Minnetonka, MN with his wife Melita and daughter, Ciella.
Gary is a retired math teacher, coach, and athletic director. He has been inducted into the Iowa baseball coaches Hall of Fame, the National coaches Hall of Fame, and the Iowa athletic directors Hall of Fame.
Gary has served Central Gardens as a volunteer since 2013. He also volunteers at Hospice of North Iowa, Mercy Hospital, Clear Lake Noon Lions, Zion Lutheran Church in Clear Lake, and Newman High School in Mason City.  He currently serves on the board of directors of Apple Valley Assisted Living, the Newman Foundation, and the Iowa Baseball Coaches Association. He recently served as a mentor and is a former president of the Zion Lutheran Church Endowment.



David Burgart

David Burgart of Clear Lake joined the Central Gardens board of directors in November 2019. He began volunteering at the Gardens in 2014 and has been more involved since retiring in 2016 after forty years of work as a software engineer. He grew up on a family farm in northeast Iowa that was self-sufficient with milk cows, chickens, and a very large pond and orchard. David loves visits with his grandchildren, camping, canoeing, gardening, reading, and volunteering for other organizations such as the BSA, RSVP, and SHIIP. He is looking forward to helping Central Gardens grow and succeed in its third decade of operation.


Merlyn Tiedemann

Appointed to the board just in time for the 2020 season, Merle Tiedemann's love of the outdoors began on the farm he grew up on in northwest Iowa.  After retiring from Holcim Cement, Merle and his wife Julie became volunteers at the Gardens.  Their relocation to Clear Lake has allowed them and their grandchildren more time to enjoy working in Central Gardens.