The Marion County Master Gardeners are holding an open house for six area gardens on July 9 and 10. The tour is being used as a fundraiser for Marion County Habitat for Humanity. Those interested are asked to start at the Bessie Spaur Butterfly garden outside Knoxville Hospital & Clinics. After making a $10 donation to Habitat for Humanity, visitors will be given a map to all six gardens, and are encouraged to visit them in any order. The gardens are open for visiting between 10 am and 4 pm Saturday, and 1 to 5 pm Sunday. Children 12 and under are admitted for free.