National Garden Month: Mulch can reduce evaporation & save water

April is National Garden Month! High Plains Underground Water Conservation District (HPWD) reminds gardeners that adding mulch to flowerbeds can help save water by reducing the amount of moisture lost to evaporation.

"Few gardening practices are as effective and easy as mulching," says HPWD Education and Outreach Coordinator Katherine Drury. She is also a Texas Master Gardener.

She said a two to four inch layer of mulch can help reduce the amount of moisture that evaporates from the soil. This, in turn, decreases the amount of additional irrigation needed to replace the lost moisture.

"Mulch provides many benefits to a landscape," said Drury. "It reduces soil compaction and erosion, it keeps soils cooler in the summer and warmer in the winter, and it can help reduce annual weed populations that compete with desired plants for water. In addition, mulch improves a home’s curb appeal by giving the landscape a polished look.

There are two categories of mulch: organic and inorganic. Each has its benefits and drawbacks. The type of mulch you choose depends on your overall garden goals.
 

A layer of  ORGANIC MULCH  can help reduce the amount of moisture evaporating from the soil.

A layer of ORGANIC MULCH can help reduce the amount of moisture evaporating from the soil.


Organic Mulch

Organic mulch is made from materials derived from living matter that will decompose over time. This type of mulch includes wood chips, bark, leaves, composted cotton burrs, and straw.

These items can be found at local garden stores. However, if you are on a tight budget, some municipalities offer free mulch at their recycling facilities. As these mulches break down, you can till the remnants back into the soil to boost its organic matter content and water holding capacity.

Composted cotton burrs are a favorite for gardeners on the South Plains because it is a locally-produced product. “Gin trash”, or the hulls and stems leftover from the ginning process, can be aged and composted to begin the decomposition process. Composted cotton burrs are excellent at holding moisture.

INORGANIC MULCH  (granite) covers the landscape next to the rainwater harvesting system at the City of Wolfforth Public Library.

INORGANIC MULCH (granite) covers the landscape next to the rainwater harvesting system at the City of Wolfforth Public Library.


Inorganic Mulch

Inorganic mulches are made from materials that do not decompose. These include crushed granite, river or lava rocks, rubber, plastic sheeting, landscape fabric, and even tumbled glass.

Depending on the type, inorganic mulches are effective in reducing soil evaporation and reducing annual weed populations. These types of mulches do not need to be replenished as frequently as organic mulches.

Rocks, crushed granite and tumbled glass are popular ways to decorate a landscape or fill landscape paths. Instead of pouring concrete or other pavement for garden paths, consider using inorganic mulches to allow water to soak into the soil instead of collecting on nonpermeable hardscapes.
 
As a general rule, maintain a two to four inch layer of mulch year round. Replenish organic mulches every time the garden is replanted or when the mulch layer decomposes by half. If you have a flower bed that tends to flood during rain events, explore heavier or anti-float mulches. Whichever type of mulch you use, make sure not to pile it up around the base of plants or trees.