Extension Master GardenerSM Volunteers of Buncombe County

Mulch

Should I Use Rubber Mulch?

This past week’s garden tasks have included the prep and thought of getting mulch spread.   Lots of mulch.   We have a pretty good size property and if the whole landscape were to get mulched at one time, it would take 25-30 yds of mulch.

Oh, my back aches!
Oh, my back aches!

My back just isn’t up to the task!   The most I have spread in any one purchase has been 10 yards…usually smaller loads, a little at a time.

If I were smart, maybe I should consider using more permanent mulch….once it’s down, maybe I’d have the job done for about 10 years!   By that time, I’d be too old to worry about mulch.

It seems that most all of the organic forms of mulch are only going to last a couple of years without having to be freshened it up.  So, I’ve done a little research on more permanent mulch…RUBBER MULCH.   Rubber mulch comes up on every internet search for permanence…Let me tell you a little about rubber mulches.   They are all made of scrapped car tires.   Of course, all of the positive things about rubber mulch are published by the folks that are trying to sell me on their product.

Rubber mulch professes to:

  • have no odor, looks like shredded wood
  • comes in numerous natural (or unnatural, i.e. Blue) earth tone colors

BlueMulch

  • be safe for plants and pets
  • controls weeds
  • not house or feed insects
  • allow penetration of water and fertilizers
  • be economical due to the permanence (definitely not due to initial cost)
  • be good for the environment, because no trees are cut down from using it
  • be good for the environment (270 million scrap car tires yearly that won’t go to the landfill)

With all of that being said, I should use rubber mulch, right?    Well, after thinking again (and reading several articles),

I’ve concluded that Rubber mulch:

  • does smell at higher temperatures
  • really doesn’t look like real wood up close
  • research (primarily done by Washington State University) shows that the chemicals that synthetic rubber are made of are toxic.  Aluminum, cadmium, chromium, copper, iron, magnesium, manganese, molybdenum, selenium, sulfur, and zinc have all been identified in laboratory and field leachates.  The chemicals leach into the ground, thus, the groundwater, etc., plus will actually kill the plantings.   More info on this is available from the following article:   http://www.theinformedgardener.com, written by Linda Chalker-Scott, Ph.D., Extension Horticulturist and Associate Professor, Puyallup Research and Extension Center, Washington State University.
  • studies have shown that mulch made from wood chips, have done a better job of weed control than rubber mulch.  Also, sawdust was found to be a better mulch for Christmas tree production in terms of weed control, microbial biomass, and soil chemistry.
  • isn’t really permanent…oxidation actually begins to turn them cloudy, white.   The manufacturers say to buy product with UV protection….MORE CHEMICALS, duh?
  • is very flammable and is hard to extinguish.  (Ever had a kid’s bottle rocket land in your yard? or had hot charcoal to get spilled beside the patio?)
Rubber mulch, shown flaming, produced the highest flames and temperatures of the eight mulches tested.. Courtesy of the UC Division of Agriculture and Natural Resources
Rubber mulch, shown flaming, produced the highest flames and temperatures of the eight mulches tested.. Courtesy of the UC Division of Agriculture and Natural Resources

Should I use rubber mulch?   I think I’ll go the organic route.   What about you?

Article written by Patsy McNatt, Extension Master Gardener Volunteer.

To Mulch or Not to Mulch…That is the Question!

This is the sort of “between the seasons” period when we sometimes look around for things to do in the garden, just to be outdoors on nice days.  And checking the mulch in your shrub borders or flower beds is one of those things than might occur to you.

But why mulch in the first place?  Well, mulch can keep down weeds. It won’t prevent all their seeds from germinating, but it can make it easier to pull them. It can insulate the soil from temperature swings, both summer and winter, and help retain moisture so that plants have a constant supply.  An absorbent mulch can prevent splash that might pass a disease from the soil to the plants and control erosion from water and wind. And as it decomposes organic mulch feeds the plants and the worms, microbes and other organisms that benefit the plants.

straw mulch to discourage weeds and retain moisture
straw mulch to discourage weeds and retain moisture

And, it can add to the asthetics of the garden just by providing a unifying feature.

“Should mulch be replaced every year?” No! Replenished perhaps but not removed and replaced.

“Can I use cardboard or shredded newspaper?” Sure, they’re organic and will decompose.  But consider that voles can find shelter under the cardboard and shredded newsprint may blow around. And there is controversy as to whether office paper should be used at all because of the various chemicals involved in its production.  I’d avoid it as a mulch. Just ship that paper off in your blue bins.

“How deep should mulch be?” Three to four inches is enough, and of course that will be reduced as the mulch composts.

Say NO to Mulch Vocanos
Say NO to Mulch Vocanos

The exception here is around trees or shrubs. Mulch piled against the trunk can serve as an “umbrella” shedding water that the roots need or when it does retain moisture two things may happen: the new roots grow upward rather than down or horizontally and the added moisture can lead to fungal canker and trunk decay. You want to be able to see the curve where the roots go out from the main stem. Don’t create a “volcano”!

Article written by Glenn Palmer, Extension Master Gardener Volunteer.

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