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Staff & Board

Staff and Board Members

Board of Directors

A 14-member board of directors makes fiduciary and policy decisions guided by these six commitments:

  1. Promoting horticultural and environmental stewardship
  2. Building the infrastructure of our free public garden space
  3. Enhancing learning opportunities for members and guests
  4. Being inviting to all
  5. Being responsible stewards of our resources
  6. Achieving excellence in all that we do


Board Members


Becke Dorenbush


Becke Dorenbush has watched Central Gardens grow and change since its inception 20 years ago. She has seen buildings built, gardens mature, and events and children’s programming develop. And as she witnessed upgrading and improvements come to completion in 2020, 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


Leigh and her husband Stuart have been residents of Clear Lake since 1982 when they married and moved 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


Ann is a master gardener who spent most of her career in finance in the Washington DC area and returned to Iowa in retirement. She now lives in Clear Lake. 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.


Donna Dull


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 were done on both the maternal and paternal side of her family, so when the idea of a public garden was being discussed, 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


Roy grew up as a third-generation avid gardener. Being a farmer was a natural extension for pursuing his love of the land and an appreciation of what it can produce. He is pleased to be able to volunteer and be a part of what he considers a valuable asset of North Iowa. After leaving his gardens on the farm and 40 years of accumulation and labor of love, he and his wife Patty wanted to be a part of Central Gardens of North Iowa. He looks 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. Andy is a lawyer with the Heiny, McManigal, Duffy, Stambaugh and Anderson law firm. 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 of 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 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. 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 large garden and orchard. David loves visits with his grandchildren, camping, canoeing, gardening, reading, and volunteering for other organizations such as the RSVP and SHIIP. He is looking forward to helping Central Gardens grow and succeed in its third decade of operation.


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 arrangements, 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 currently works 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®. She is 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.

Ciar Carnall 2021

Ciar Carnall


Ciar loves plants and flowers and so it was fitting for her to get married in Central Gardens. She and her husband have one daughter and live in Clear Lake where she works as a full-time florist. Ciar has volunteered at Central Gardens for the last eight years and has been involved with Fresh on Fridays, the Garden Fiesta, Picnics and Performances, and planting beds. She has served on the board of directors since 2019. 


Vernon Johnson


Vernon and his wife Heather moved to Clear Lake in 2005 becoming active in the community as youth coaches in basketball and volleyball. Vernon works at Kingland in the marketing department and has volunteered for a variety of events and organizations such as North Iowa Fire,  the Clear Lake Wellness and Recreation facility and Tri Clear Lake. Vernon and Heather have three daughters. 

Help Us!


Learn about ways you can help us out at the gardens. We are always looking for volunteers throughout the season.


Staff Members


Joni Frederick

Development Coordinator

Since retiring as a corporate negotiator with Wellmark Blue Cross Blue Shield in Des Moines and relocating to Clear Lake in 2016, Central Gardens has been one of Joni’s favorite places in north Iowa. She has served the Gardens since 2017 as a committee member for the annual garden party and now serves as its part-time development coordinator. Local music, cooking, and caring for plants and gardens are some of Joni’s other interests.


Drake Tiedemann

Part-Time Summer Groundskeeper

Drake Tiedemann, a junior at Northwood-Kensett High School, has joined Central Gardens as a groundskeeper for the summer. Drake’s grandparents, Merlyn and Julie Tiedemann, brought Drake along with them to work in the gardens early this season and his enthusiasm and spirit was readily apparent. After just three visits, he was asked if he wanted to work here.

Drake enjoys being outdoors and appreciates the beauty of the Gardens. He participates in wrestling and cross country during the school year. Welcome Drake! We’re glad you’re here!


Nikki Johnson

Office Coordinator

Nikki and her husband Rick are both from Belmond, Iowa and recently moved to Latimer.  Nikki joined the Central Gardens team in June of 2021 as Office Coordinator, and is excited to help CGNI continue to provide abundant educational, recreational and cultural programs for our communities to enjoy.

Nikki is also the Educational Coordinator for the Surf Ballroom & Museum in Clear Lake, carrying out all educational and community outreach programs.

Nikki and her husband are excited to welcome their daughter to the world in September.

Nikki also enjoys volunteering at local animal shelters, doing anything outdoors, playing music, cooking, and baking.