Green Mulch – The Many Benefits In & Around the Garden

Sedges, botanically known as Carex are truly an underused group of grass-like plants for the Garden. Found around the globe, there are a number of species native to North America that have only of late come into the spotlight as a living, green mulch. Not only do they look great and have deer resisting properties, many require very little care and ease a gardener’s workload!  

Carex & Sedges – The Benefits of Green Mulch for the Garden

Carex is a huge family with over 2,000 species that are known for their ‘edges’ or serrated leaf margins. The name Carex was coined by Carl Linnaeus (1707-1778) and comes from the Greek Keiren, which means to cut – a reference to the leaves. Interestingly, for those who enjoy words, the name Sedge was derived from the Old English Sagu, which means saw, another reference to the foliage! The flowers of sedges are typically not very showy, but do possess a subtle beauty for the inquisitive gardener. Unlike grasses, the flowers or inflorescences of Sedges and other green mulch plants are monoecious, with the male and female organs found in separate ‘flowers’ on the same plant. In fact, the separate flowers are often on the same stem, with the male flowers located just above their female counterparts. 

living mulch
Come spring, the new foliage literally emerges up and through that of the previous year, making the plant not only very low in maintenance, but self-mulching!

The Benefits of Oak Sedge in a Garden

Carex pensylvanica or Pennsylvania Sedge was one of the first native species whose assets were broadly promoted to the gardening community. The species epithet was created by the French naturalist Jean-Baptiste Lamarck (1744-1829), describing the general area from where it was collected. It is also called Oak Sedge, for its tendency to grow amongst Oak Forests. This species has very attractive and delicate foliage that is a mere ⅛” wide and up to 12” in length.  

Oak Sedge is a great choice for green mulch, as it spreads by underground stems, allowing it to quickly expand and become a dense groundcover.  As the foliage lengthens, it prefers to lay against its neighbor, producing an overall effect similar to rushing water, as seen in the image above.  As a result, even though the foliage is 12” long, the overall height reaches a more demure 6-8”.  This plant thrives in dry shade, making it a great alternative to turf grass, Pachysandra, Vinca, and English Ivy.

In addition, Oak Sedge can be mowed should the gardener wish and it tolerates light foot traffic!  With the advent of December’s chill, the foliage fades to tan and remains attractive through the winter months.  Come spring, the new foliage literally emerges up and through that of the previous year (as seen in the photo, above left), making the plant not only very low in maintenance but also self-mulching!  

The Advantages of Cherokee Sedge as Green Mulch

Carex cherokeensis is a taller clump-forming sedge that can be used as a green mulch. It remains green through early winter. The picture at right was taken in January.  Described in 1824 by the German-American botanist and mycologist Lewis David von Schweintz (1789-1834), the plant was named after the town of Cherokee, Texas.  Native from Missouri and North Carolina south to Texas and Florida, Cherokee Sedge is naturally very heat and drought tolerant.  Unlike its aforementioned cousin, the 12” long foliage not only remains upright and arching, but also glossy! The plant produces shorter rhizomes than Oak Sedge, but it still makes a very effective groundcover or can be interplanted with shade-tolerant perennials. Plants prefer shade to part shade and are adaptable to soils from dry to very moist, making it ideal for rain gardens!  

living green mulch
Carex cherokeensis is a taller clump forming sedge that remains green through early winter. This picture was taken in January.

The Uses of White Tinged Sedge

Another fine textured and clump-forming sedge is Carex albicans, the White Tinged Sedge with its small yet attractive off-white inflorescences (as seen at right).  The species epithet is from the Latin Albicō, meaning to become white, a reference for when the plant flowers.  It is very low growing, as seen in the image below, and is native to well-drained woodlands. Its low stature makes it ideal for under-planting and filling the areas between various shade-loving perennials like Snakeroot, Foam Flower, and Trillium. 

In this day and age when we are looking to reduce our impact on the world, what could be better than a drought-tolerant green mulch? It is a design strategy that Mother Nature repeatedly uses and it’s now prime time to follow her inspiration and consider planting green mulch.