Each year in the spring, remove the previous years litter by mowing or weed whipping at a height of one inch.  This can be performed once snow is off the ground.  Remove any thatch build-up since thatch insulates the ground,  keeping the soil colder longer, thus reducing the growing season of the garden. It is beneficial to leave plant material over winter as it can provide food and shelter for many birds and insects. This should be a relatively maintenance free garden as all plants are native to Michigan, but if there is a drought the plants would love a little extra water. Finally be sure to sit back and enjoy your new peaceful haven!