Jan Laurens and Robbrecht's Gardenhouse is a total jewelbox. It's so lovingly and thoughtfully constructed and maintained, and they struck a great balance with offering information and affording privacy. They had a gratis minibar with softdrinks, wine, and chocolates waiting, as well as a guide to the area, and Robbrecht was touching-up the (perfect-looking) exterior trim as I arrived. It was like staying in a boutique hotel, except all of the cords had been built into the walls, because their attention to detail was that high.
Their garden is a marvel- it abuts a canal that you walk around a hedge and under some willows to see, and the garden has immaculate annuals and perennials, as well as some specimen trees. It's not directly downtown, but if you don't mind a short trip with Uber, taking the RET, or riding the bikes, which is really fun, you'll get to discover some elegant Rotterdam neighborhoods, including Jan Laurens's.
Thoughtful folks and a beautiful place.