Spring has sprung and tis the season that most of us mulch our flowerbeds and trees. Questions I often hear are: 

Which type of mulch is best? 

What kind of mulch should I use? 

I heard that cedar is good mulch, is it? 

Is it okay to use leaves and pine straw as my mulch? 

Can I use compost as mulch? 

Or perhaps the negative: 

I bought this black mulch and everything became stunted or died – what happened? 

I bought this black mulch and if a few weeks it had turned grey, what’s wrong? 

I bought this red mulch and my plants turned yellow – what happened? 

I saw this bag of rubber mulch that is supposed to last forever, does it really work? 

Or the interesting: 

I read that if I change my mulch to ____ then I can increase the sweetness of my tomatoes by 20%, is this true? 

I heard that this type mulch ____ helps suppress fire ants? 

What type of mulch turns gumbo clay into beautiful loamy soil?

In this column we are going to answer your questions on mulch. To get started, mulch is just like any other product, some are very good and some are very bad. In general just like everything else in life. 

To be a successful gardener in Texas one must mulch (and everywhere else also). Mulch comes from the German “molsch,” meaning “soft,” and refers to any loose, generally soft material that is laid down on top of the soil to protect a plant’s roots or spread lightly over the plant itself. Mulch is not a soil amendment; it is a covering or surface layer used to protect the topsoil. Nature does not allow bare ground hence neither should we. Mulching is considered to be the most important step in any gardening program. All natural or organic mulches will improve the soil but like all things, they vary in quality and effectiveness. Good mulch lets air (oxygen) and water enter the soil and allows carbon dioxide to escape. Good mulch will readily decompose releasing the stored nutrients and will provide microorganisms, earthworms and beneficial insects a good home and food source. 

Since it is the mulching season let’s start with the better types of mulch. Three of the best mulches for use in gardening are: Native Mulch, Compost, and Pine Straw or Leaves. 

Native Mulch or Native Hardwood – “Native” mulch is made from recycled fresh green tree and brush material that was recently alive and comes directly from a grinding operation. Native mulch is produced from a mix of native trees (primarily hardwoods) and brush with only a small amount of bark. Good native mulches have a high percentage of buds, shoots, leaves, and cambium layers in them. These materials are rich in protein, vitamins, minerals and other nutrients which is the reason deer and other animals eat them as a food source. Hence, these native mulches are many times higher in nutrients and value than bark mulches. Native mulches encourage the biodiversity of beneficial microbes and earthworms in the soil. They feed the plants naturally as they decompose, and they help prevent plant and soil diseases. 

Some suppliers will compost the native mulch further increasing its value and effectiveness. The heat of the composting process kills any pathogens and weed seeds that might have been 

present. The composting process concentrates the nutrients contained in the raw material and stabilizes nitrogen in a form beneficial to plants. The composting process breaks down the cellulose contained in the raw material rendering it a far less attractive home for termites and fire ants after it is applied, compared to bark or other woody mulches. Additionally, the composting process turns the material a rich beautiful deep chocolate brown color. 

Compost – For decades good compost has been called “Black Gold” by experienced gardeners. Even though most of us think of compost as a soil amendment, it can be used as mulch. It will rapidly improve the soil quality and feed one’s plants as it breaks down hence it will have to be replenished more often. 

Where compost shines as mulch, is on Turfgrass where it can prevent diseases and greatly reduce water requirements. A fine screened (3/8” minus) Leaf Mold Compost applied ¼ inch thick coupled with a good organic fertilizer like MicrolifeTM will prevent most disease problems, greatly reduce water requirements and green up your lawn with thick beautiful grass. 

Pine Straw or Leaves – Leaves are how nature mulches the forest hence it is a pretty good mulch. Leaves are great for weed control and often work better than other types of mulch in this regard. However leaves may blow around and be a little too messy for some. Pine straw does not blow and it is a little more expensive than other types of mulch. However when used correctly and with the right species of plants it can be very beautiful. Note: It would take a several foot thick layer of leaves to give one the soil improvement that 3” of native mulch or compost will give.