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Sunday, May 16, 2010

The Dirt on Mulch in Florida



Editor's Note: The author of this post, Steve Woodmansee, is the owner of Pro Native Consulting in Miami, and also the Vice President of Finance for the Florida Native Plant Society. Steve has written a comprehensive piece on the subject of mulch, which we are going to present in two installments. If you want to learn more from experts like Steve, come to the FNPS conference in Tallahassee, May 20-23. You can attend all days or single days. There will be great field trips, too, check the link!

Mulch can be an important part of landscaping and installing native plants.  Mulch is typically organic matter consisting of wood chips, twigs, bark, or leaves/needles. Some people also use gravel and rocks, or even products made from recycled tires in lieu of natural organic mulch. 

Benefits of mulch can include:
  1.  Increasing nutrients to the plants, thus building the soil.
  2. Conserving water.
  3. Insulating the soil and plant roots (from both heat and cold).
  4. Stifling weed generation.
  5. Providing a habitat for wildlife.
  6. Creating a stylized landscape.
               Hardwood hammock forest using local tree trimmer mulch

Mulch Drawbacks
Before purchasing and applying mulch, determine first whether it is needed, and second what kind is right for you. Some mulches can be messy in high traffic areas.  Another undesirable characteristic is that some mulches float during heavy rains, and will often travel downhill into areas where it is not desired.  During droughts or hot times of the year, organic mulch is flammable, and probably not recommended for planting adjacent to the home.

Organic mulch provides habitat for a variety of smaller critters including some which are often considered a nuisance, such as carpenter ants and termites.  Some organic mulches may be more resistant to these insects, but remember that one of the purposes of using native plants is to increase wildlife in the yard.  Many species of birds, lizards, and mammals consume these and other critters, so they are an important part of the food web.   For example, the once more common Northern Flicker has a diet primarily of ants and termites.  If termites and ants worry you, consider using an inorganic mulch like pea rock or recycled tires.

Mulch is also not suitable for some types of habitats.  Pine dominated habitats are relatively low in nutrients compared to broad leaf habitats.  With pineland plantings, some recommend using pine straw (pine needles), however I do not.  Walking through a healthy pineland, you will notice that there aren’t very many pine needles or leaves on the ground.  This is because fire, a natural part of a healthy Florida ecosystem, removes this excess organic material.  The same qualities  that we desire for  stifling weed generation also inhibit important wildflower and grass seeds from regenerating in landscapes heavily laden with pine needles or pine bark.  Butterfly gardens, like pinelands, often incorporate wildflowers, which will not regenerate as successfully through a thick layer of mulch.

Bare soil in a pineland planting

Bare soil or sand is important habitat for certain beneficial wildlife species, such as antlions, wasps and their kin.  Many wasps and bees make burrows to rear their young.  So keep some areas of the yard bare.

For almost all other cases, mulch is ideal, and almost certainly applicable to some part of your landscape.  Examples include vegetable gardens, fruit trees, and native hardwood forest communities.  Stylized landscapes also incorporate mulch.  It should be noted that in the industry, mulch is rated on its durability (meaning its ability to persist in the landscape, to not break down or compress) and appearance. These may not be the goals of everyone’s landscape.

Mulch Application
Mulch is simple to apply.  For individual or specimen plantings, plan to create a ring around the tree or shrub.  Apply a thick layer of mulch up to 8 inches high at the edges.  Most recommend only 3-4 inches thick, however I find this to be too thin, and in most cases the mulch will settle.  Be sure and keep mulch 3 – 4 inches away from the trunk of the planting, and thicken as you go away from the tree.  For newly planted material, I recommend that mulch extends to at least the drip line of its canopy.  This is so new roots which reach to the edge of the canopy benefit.  Expand mulch rings as the tree or shrub grows.

For massive contiguous plantings, such as habitat creations or large landscapes, spread mulch across the entire area, following the above guidelines.  Once settled, the mulch tends to stay in place, but it is helpful to create a border of landscape timbers, bricks, or stones to prevent mulch from leaving the area.  Plan to reapply mulch as needed.  You will know when it gets thin.  Eventually your created habitats will re-mulch themselves as  natural detritus is formed from falling leaves.


2 comments:

  1. An article on why bare soil is essential to bees: http://nature.berkeley.edu/urbanbeegardens/general_mulchmadness.html

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  2. An article on why bare soil is essential to bees: http://nature.berkeley.edu/urbanbeegardens/general_mulchmadness.html

    ReplyDelete