Board of Directors


Becke Dorenbush, President

Becke Dorenbush has watched Central Gardens grow and change since its inception 20 years ago. She has watched buildings be built, gardens mature, and events and children’s programming develop. Now, as we watch 2020 Upgrade improvements come to completion together, she looks forward to a memorable 2021 with the Plant Sale and Gardening Fair, Fresh on Friday, the Summer Garden Party, Picnics & Performances, the Fiesta, Movement Saturdays, and much, much more.
Becke has been a dedicated board member since 2017, a regular volunteer at Down & Dirty, and a long-standing garden adopter.  She also serves on the Gardens Events and Finance Committees and chairs the Membership and Marketing and Summer Garden Party Committees.

Leigh Trembath, Vice-President

Leigh and her husband Stuart have been residents of Clear Lake since 1982 when they married and moved here from Chicago.  Planning to stay just a few years they found Clear Lake a wonderful place to live so they set down their roots and raised two wonderful daughters here. Volunteering and being an active member in a community is important to Leigh, with past participation on the North Iowa Soccer Club, Healthy Harvest of North Iowa, and Clear Lake Farmers Market boards.  Since 2006, Leigh has been involved at Central Gardens with a special focus on education, developing Fresh on Fridays, and building the BEE Happy Discovery Garden.  Leigh gardens organically and feels it is important to be a curious gardener, asking questions and learning from nature.  When not gardening, Leigh loves taking photos, walks in nature, reading and spending time with family, which also includes their two bernedoodles, Eva and Oscar.

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.


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.


Barb Leonard

Barb retired after teaching first grade for 26 years. She has lived in Clear Lake with her husband Jim all of their married life – 47 years. They have two daughters, a son-in-law, and two granddaughters. Her hobbies include painting (oil, acrylic, and watercolor), golfing, crossword puzzles, reading, and flower gardening. She volunteers at Fresh on Fridays cutting and making arrangement which she loves.

Bri Sholly

Brianna (Bri) lives in Ventura with her husband, two toddlers, and two dogs. Their family loves spending time outside gardening, birdwatching, hiking, and exploring. She has a background in conservation, having received her M.S. in Wildlife Science from South Dakota State University in 2015. Bri’s current position is as the Youth Services Librarian at the Clear Lake Public Library. She has really enjoyed partnering with Central Gardens over the last few years, including Story Time in the Gardens and the more recent StoryWalk®, and she’s excited to take on this new role and become even more involved in the Gardens.

Jennifer Merfeld

Jennifer and her husband Bob moved to Clear Lake after graduating from Iowa State University. Together they raised three active children while Jennifer worked as a marketing professional in the technology sector and Bob made his career in the agriculture industry. As a long-time resident, Jennifer has volunteered for a variety of events and organizations, including as a youth soccer coach for North Iowa Soccer Club and as a member of the Clear Lake Parks and Recreation board. Having been raised in a small town nearby, Jennifer spent many weekends and summers in Clear Lake and continues to enjoy its beauty and charm.