Cindi: Due to a couple of recent restaurant fires in the Louisville area, I am looking to stop using wood mulch and use something with less flammable potential. Is there any non-wood mulch that you particularly like? I am especially interested in lava rock.

BTW: Someone recently called in to your radio show and apparently stumped you with a question about using glass as mulch. I found this short video (2 minutes, 38 seconds) clip on using specially glass as mulch. Thought you might find it informative.

http://www.brightcove.com/title.jsp?title=769355741&channel=340475606

There are lots of inorganic mulches to choose from; we used lava rock pretty extensively when I was with Brightside and had good luck with it.

Generally speaking, there are two types of mulch-organic and inorganic.

Organic mulches would include any material that is readily degradable or that is derived from a living or previously living organism. Organic mulches include hardwood, cypress and pine bark mulch; leaf litter, straw, newspaper, compost and manures would also fall in this category.

Inorganic mulches then would be derived from non-living materials. Clear or colored plastic sheeting, geotextiles, rock, recycled rubber materials and carpets would be considered inorganic mulches.

Both types have advantages and disadvantages. And within in category, there are certainly pros and cons.

Personal preference certainly plays a major part in the selection of mulches. All mulches whether organic or inorganic are beneficial in that they help to regulate the soil temperature, they hold in valuable moisture, and they suppress weed competition.

Organic mulches have the added benefit of soil improvement. As organic mulches degrade, they add valuable nutrients and organic matter to the soil. This will improve the cation exchange capacity of the soil—nutrients will be more readily available to plants, and the water holding capacity will be improved. These are major benefits or plant material.

The flip side of this is that they do degrade at various rates and therefore require retreatment more often that inorganic.

There is also some question as to whether or not organic mulches like hardwood mulches will attract termites. Termites are of course naturally occurring organisms found underground or infesting wood structures in Kentuckiana, but I’ve never really seen any evidence that organic mulches will bring then nearer or into a home. It is certainly advisable to keep a “Dry Zone” near the foundation of the house, an area of several inches that is free of organic materials like mulches that would hold water and potentially lead to infestation from opportunistic organisms.

Keep in mind that molds and mulch do sort of go hand in hand. Organic mulches are made from materials that are decaying and in order to decay, they need microorganisms like fungi to participate in that process. This is actually a good thing, because it is generally believed that if you have lots of ‘good’ microbes working in the soil, they will out compete the ‘bad’ microbes responsible for causing diseases. More often than not, these good microbes are working away without any notice from us, but occasionally when they are in the reproductive phase they will become more noticeable with white or yellow fruiting spores. You can generally take this as a good sign.

Although inorganic mulches do typically last a long time, this can sometimes be something of a drawback because they can be difficult to remove. For instance the only way rock or rubber mulch is going to go away is if it is hauled away.

If you have mulches that have not degraded much over time, more often than not, you can simply rough up the surface a little bit to refresh the color with even adding more. If you are using especially durable mulches, and the layer ahs gotten thicker than a couple of inches, rake the mulch up a bit to refresh it and then apply a very thin layer to create a just laid look.

Thanks for the informative video about recycled glass mulch---does anyone out there know where to find it in the Kentuckiana area?