Like its big brother The Growlight Garden, the Micro Growlight Garden relies on a clever but simple self watering system. The planted trays sit on a thick fleece mat that has one end dangling into a reservoir of water. The mat draws the water up by capillary action so it stays evenly moist. The planted trays easily draw water from the mat as it is needed in the soil. All the user has to do is top up the reservoir with fresh water every few days, and the system runs itself. Between uses, the mat can be cleaned with regular dish soap or a biodegradable laundry soap. A few drops of bleach will kill any mould or mildew spores that might appear on it. But after months of use, you may choose to replace the mat with a Replacement Mat for Micro Growlight Garden.