Mulch is an integral part of our landscaping. It enhances the appearance of our home, adds nutrients to our soil, suppresses weed growth and helps the soil retain moisture. It also seems though, that mulch is often misunderstood. For this column, I have asked Kevin Donnelly, a horticultural soil scientist to answer a few questions about mulch. Kevin is a key member of the Quality Control Team at Midwest Trading.
What is mulch?
Mulch is a layer of material applied to the surface of the soil.
What is it usually used for?
Biggest reason is to prevent weeds and protect the soil. In landscaping it will also add to the aesthetic of the bed. Mulches help maintain soil moisture, reduce erosion and insulate from temperature extremes.
What is most mulch is made of?
Plant based products line bark or wood chips, some compost as well. In vegetable applications, straw can be used. On large scale there can be a cover crop that then can be considered a green mulch.
Mineral. Different stones are used in landscape settings such as lava rock, pea gravel and other stones.
How do the types of mulch vary?
They vary in look and functionality. In an annual bed, you will likely want a finer texture mulch and need to apply yearly. In perennial or wood plan areas, you can use a coarser textured mulch and may not need to apply every year. Perennial beds over time will fill in and less mulch if any will be needed.
Is there any type of mulch that you do not recommend homeowners use?
Synthetic mulches like rubber. I would also caution against stone mulches as they have two drawback. It can reflect heat back up to the plant material and dry out plant material, and it will overtime collect soil and other materials and weeds will grow into it. Removing rock can be very difficult, especially if a proper landscape fabric was not put down first.
How should a homeowner make a decision regarding the type of mulch he or she should use?
Application and personal preference. Mulch is a part of the landscape view, so the color or the texture of the mulch and the look a homeowner is trying to get comes into play. Dyed mulches will lose their color over time. That time will vary between suppliers as well. The good thing, as with gardening in general, is that you can try new things each year or two. If you plant annuals every year, you are going to need to mulch every year. Try something out, if you like it and it works, great. If not, try something else. Landscape and gardens evolve over time and there are ample opportunities to try. Unlike siding, or other housing projects, which are more of an investment and more permanent.
Depending on the planting situation, is there a certain amount of mulch that you recommend?
2-3 inches usually does the trick. Avoid mulch volcanos around trees, which can be detrimental to a tree. Mulch should be near the soil level
Is there a time of year that you recommend mulch be spread?
Spring and fall or anytime a new landscape is being installed. In the spring when new plantings are happening, or spring garden cleanup a layer of mulch is needed to prevent weeds from growing up. In the fall mulching is helpful because it will offer some protection to plants by insulating a little bit against cold temps and likely reduce heaving that occurs from freeze thaw cycles.
Why does it seem that mulch needs to be spread every other year?
It breaks down over time and adds organic matter to the soil. This is a slow process but it will improve soil health. Stone mulches or other non-organic ones still need to be maintained as stuff will wash into it, or fabrics may break down over time from UV.
What are the benefits of putting mulch down regularly?
Less weeding for one thing. It will keep the landscape looking good, and depending on the site, prevent soil loss from rain. You want to protect the soil environment.
How does mulch help the plants?
It evens temperature and adds moisture to the soil.
How does mulch help the soil?
It will add organic matter back to the soil, which improves soil health. Homeowners need to remember that they are dealing with an ecosystem under foot, and if they treat it well, plants will thrive.
What are some common problems that you see with regards to how mulch is spread?
Either not enough or too much. When mulch is mounded around the trunks of trees a few things can happen that will end up damaging that tree. In the winter, critters may burrow in there and start eating the bark. Roots may form in the mulch layer and not into the soil.
Kathleen Carr is the owner of The Growing Scene, Inc., a garden center and landscaping company. She can be reached by calling 815-923-7322 or Kathleen@thegrowingscene.com. Have a gardening question? Please contact her. She may address it in an upcoming column.
