What is Marsh Hay and Where Do You Get It?by Karla Lynch on 02/12/11
Back in the day, when I was studying horticulture in college, all of the books suggested using marsh hay as a winter mulch. It appears that most of these books were written by folks on the east coast where this plant was introduced from Europe. It wasn't until I met New Yorker, Charles Lewis (deceased), who explained this mystery to me when he was a senior staffer at The Morton Arboretum. Marsh hay is Phalaris arundinacea, commonly known as reed canary grass. You may have seen the variegated type known as Gardeners' Garters.
As it turns out, this is an agressive grass that has invaded many wetland areas. I see it growing in low fields all around Kane County (Illinois). It does not lie flat and wet under melting snow and this is the characteristic that makes it a good winter mulch. Cut bunches of reed canary grass foliage will shade the ground, but keep the crowns of dormant or emerging herbaceous plants, including bulbs, relatively dry. If you try this, be sure to remove any grass seed heads.
Here's a chance to put those overgrown patches of Gardener's Garters to work. Cut them to the ground and use them for winter mulch.