Our Tour Guides


Dr. Denny Schrock is the Iowa State Master Gardener Coordinator. He was previously a garden editor with Meredith Corporation, where he edited 40 garden books under the Better Homes and Gardens, Scotts, Miracle-Gro, and Ortho brands. Schrock serves on the editorial advisory board of The American Gardener magazine, and in 2015 he was honored as a Fellow by GWA, the Association for Garden Communicators. Denny has extensive international experience, from living in Poland for two years, to leading student and Master Gardener study tours to Ecuador, South Africa, France, England, Belgium, the Netherlands, and Italy. In addition, he has traveled on his own to more than 30 countries around the world.



Eric Tschanz has been in the public garden world all of his career. He recently retired as the Executive Director of Powell Gardens where he spent the last 29 years. Through his involvement with the American Public Garden Association he has had the opportunity to travel and make connections with many U.S. botanical gardens. His personal travel and garden tours have taken him to England, Scotland, Ireland, Holland, France, Spain, Italy, Mexico, Costa Rica and New Zealand. Eric has an undergraduate in horticulture from Ohio State University and completed his graduate work at Longwood Gardens and the University of Delaware.




Kari Harper, owner of Hidden Treasures Tours, has undergraduate degrees in Communications and Art with an emphasis in Art History and a Masters in Project Management. Prior to Hidden Treasures Tours, Kari owned and operated a marketing and project management company. Kari began working with Mary Kroening in 2014 as her marketing consultant and assisted in the overall tour planning and administrative operations of the company. Kari purchased the company in 2017. Kari’s travel experience has taken her internationally to the Bahamas, Canada, Costa Rica, Spain, France, Romania, the Netherlands, and Italy. Her passions include art, cuisine, history, and dance.



Mary Kroening, the founder of Hidden Treasures Tours, has over 15 years’ experience leading tours throughout the world. Mary has her BS from Concordia College and her MS from Colorado State University. She started her travel career by offering horticulture study tours to Costa Rica with custom itineraries designed specifically for Master Gardener groups. Since that beginning she has arranged tours for gardeners, bird watchers, wine enthusiasts, natural history interest groups and others. Mary has two grown daughters and in her spare time enjoys travel, backpacking and gardening.



Tour Guide: SUSAN MAHR

Susan Mahr has degrees in Biology and Entomology and has been the state coordinator for the Master Gardener Program in Wisconsin for nearly two decades. As part of her responsibilities there, she has lead numerous educational tours to Costa Rica, New Zealand and South Africa, and has hosted garden-related tours for HTT to Italy and New Zealand. In addition to leading tours, she has also done extensive personal travel throughout the world, especially to see plants in habitat. Susan is also an avid gardener, with personal interests that include tropical plants, vegetable gardening, bulbs and perennials.