When you need more than just supermarket-stock plants and shrubs, I would recommend Canadale Nurseries in St Thomas Ontario. The quality and variety of trees, shrubs, perennials, annuals etc is excellent. We were looking for a Witchhazel shrub that I had seen in a gardening magazine and they had one; we also have purchased several fruit trees, roses and miscellaneous plants. They are priced a bit higher than some garden centres, but you really get what you pay for - the plants are top quality, and they come with a guarantee. They are helpful on the phone and on-site and If you sign up for their email program, you get notification of their regular sales. I highly recommend them - worth the drive.