GARDENRiver Hills garden includes formal rose garden, arboretum with treehouseMilwaukee Journal SentinelA Gothic-inspired treehouse is nestled in a red oak tree that has two trunks on the River Hills property of David and Dedi Knox, seen on June 9, 2023. The Knoxes' gardens will be featured in this year's June Open Days event that's connected to the Garden Conservancy, an international organization that promotes gardening.Angela Peterson/Milwaukee Journal SentinelA tulip from a variegated tulip tree is seen on the 15-acre River Hills property of David and Dedi Knox on June 9, 2023.Angela Peterson/Milwaukee Journal SentinelBranches and flowers from a variegated tulip tree is seen on the 15-acre River Hills property of David and Dedi Knox on June 9, 2023.Angela Peterson/Milwaukee Journal SentinelMargaret's Garden, named for David Knox's granddaughter, is in bloom on his property in River Hills on June 9, 2023.Angela Peterson/Milwaukee Journal SentinelPeony flowers bloom in Margaret's Garden, which David Knox named after his granddaughter, on June 9, 2023 in River Hills.Angela Peterson/Milwaukee Journal SentinelOne of four ponds is seen on the property of David and Dedi Knox on June 9, 2023 in River Hills.Angela Peterson/Milwaukee Journal SentinelDavid Knox walks along one of the many scenic paths on his 15-acre River Hills property on June 9, 2023. Knox's gardens will be featured in this year's June Open Days event that's connected to The Garden Conservancy, an international organization that promotes gardening.Angela Peterson/Milwaukee Journal SentinelLeaves from a Japanese maple tree are seen at the River Hills home of David and Dedi Knox on June 9, 2023 in River Hills.Angela Peterson/Milwaukee Journal SentinelLeaves from a sycamore maple tree are seen at the River Hills home of David and Dedi Knox on June 9, 2023.Angela Peterson/Milwaukee Journal SentinelLigularia desdemona plants are seen on the property of David and Dedi Knox on June 9, 2023 in River Hills.Angela Peterson/Milwaukee Journal SentinelA variety of trees, some nearly 100 years old, are seen on the property of David and Dedi Knox on June 9, 2023 in River Hills.Angela Peterson/Milwaukee Journal SentinelA variety of colorful perennials fill Anni's Garden, which David Knox named after a granddaughter, at his property in River Hills on June 9, 2023.Angela Peterson/Milwaukee Journal SentinelSum & Substance hosta are seen on the property of David and Dedi Knox on June 9, 2023 in River Hills.Angela Peterson/Milwaukee Journal SentinelA copy of the statue "Seated Hermes" is framed by Miller's Crimson, a candelabra primrose, on the River Hills property of David and Dedi Knox on June 9, 2023.Angela Peterson/Milwaukee Journal SentinelFlowers from a golden chain tree are in bloom on the River Hills property of David and Dedi Knox on June 9, 2023.Angela Peterson/Milwaukee Journal SentinelA formal rose garden is seen at the home of David and Dedi Knox on June 9, 2023 in River Hills.Angela Peterson/Milwaukee Journal SentinelA hybrid tea rose is in bloom in a formal rose garden at the home of David and Dedi Knox on June 9, 2023 in River Hills.Angela Peterson/Milwaukee Journal SentinelCelestial Shadow, a flowering dogwood, is in bloom on the property of David and Dedi Knox on June 9, 2023 in River Hills.Angela Peterson/Milwaukee Journal SentinelScotch pines, right, are among the trees in a mature pine forest on the River Hills property of David and Dedi Knox, seen on June 9, 2023.Angela Peterson/Milwaukee Journal SentinelA variety of perennials grow on the 15-acre property of David and Dedi Knox in River Hills, seen on June 9, 2023.Angela Peterson/Milwaukee Journal Sentinel