Natural/Organic Mulches Pros and Cons

Every gardener out there is looking for the perfect solution to the problem of garden weeds, maintaining soil moisture and providing some aesthetics to their gardens plots.  Many gardeners over the years including myself have turned to garden mulches in order to fill that need.  But with the plethora of choices out there it is hard to decide which direction to go.  The first choice anyone that wishes to use mulches must make would be whether to go with synthetic/artificial mulches or to go with natural mulches. 

The term natural or organic mulches covers a variety of mulch types.  This list could include wood chips, tree bark, straw, grass and pine needles. I would also include in this article the use of paper and cardboard as mulch since they are compostable and made from plant fibers.  To cover all the types would be to extensive for this article so I am just going to gloss over a couple of the more common ones and give the pros and cons for them.


Wood Mulches[1]

To get started I will cover the usage of wood products such as wood chips and bark in order to mulch gardens.  From what I have seen in my travels and my research, wood chips and bark are a favored mulch for flowers gardens, ornamental plantings and trees.  They are derived from many types of wood and are sometimes colored to provide a backdrop to flowers, shrubs and trees.  Some of the pros and cons for wood mulches are


       -Retains soil moisture

       -Adds nutrients to soil

       -Suppresses weeds if thick enough

       -Moderates soil temperature

       -Prevents erosion and soil compaction

       -Enhances beneficial organisms

       -Aesthetically pleasing

       -Can be very cheap or even free



       -Must be replaced possibly on a yearly basis depending on climate and type of wood




My Take on Wood Mulches

I personally am a fan of wood mulches for all the reason mention above plus a few more, like how easy it can be to apply and spread.  It amends the soil with nutrients and organic matter which is a huge plus in my book.  Since it does hang around for years at a time it can be tricky to use in vegetable production systems since those are relatively short-term and intensive and you don’t want to deal with leftover wood chips the next year.  On the flip side though it is a great addition to any long-term flower or ornamental plantings for preventing those windblown seeds from taking root.  I also love using wood mulches around the base of trees since it reduces grass/weed completion with that tree and it makes mowing around the tree a breeze.  All in all wood chips are a good product just make sure the wood included in the chips have no allelopathic properties or contain rot inhibiting chemicals like coal tar creosote.   


Non-Woody Mulches

The term non woody mulches covers a variety of products from grass clippings to straw all the way to pine needles and leaves.  These can be obtained either very cheaply or free with a little forethought and planning.  Case and point would be the pine needle or leaf mulches, instead of hauling them away to be burned or composted, using them in your gardens or your neighbors gardens it a free effective way to dispose of them.  The same principle could be applied to grass clippings though you would have to let your lawn get a bit long before you can amass enough grass fiber to make it worthwhile.  So pros and cons of using non woody mulches would be


       -Very cheap or free

       -Easy to obtain with forethought

       -Can make your own mulch onsite

       -Promotes sustainable growing practices             since all materials are local

       -Provides organic matter to soil

       -Provides nitrogen to growing plants                     quickly

       -Prevents erosion and improves water                    infiltration.


       -Would need to be replaced frequently


       -Could be more labor intensive to gather             and spread

       -Compacts and decomposes quicker and             may need to be applied mid year.

       -Some perennial weeds can come through           mulch if   it not thick enough. eg. Thistles.

       -May acidify soil such as in the case of pine         needle if very liberally applied

 My Take on Non-Woody Mulches

I like many things about non-woody mulches.  First and foremost in my opinion is there ease of availability.  I for example used grass clippings from the lawn around my garden plot to mulch my 12 x 12 foot garden to about 6 inches deep in grass clippings.  This greatly reduced weed pressure in my garden with only those perennial weeds making it though the mulch layer.  But since I was unable to mulch it again like that for the rest of the summer my mulch layer got very thin and did not provide all the benefits it once did.  So to sum it up they are great to use in a pinch and can work great but they have to be applied frequently since they decompose rapidly.  If you have lots of time and material to mulch with these they could be a great option for you.  For longer lasting non-woody mulches I would suggest going with straw or pine needles, due to their structure and carbon content they take longer to compact and decompose in the garden.  If you do buy straw try to buy straw labeled Weed Seed Free since it will reduce how many foreign seeds get transported into your garden.


Paper & Cardboard Mulches

The use of paper and cardboard in sheet mulching is a relatively new process and as a result of that there is not much literature out there on it yet.  What I have been able to dig up and from my experience is that it can be effective but it does come with potential problems.  In my experience it can be very effective for preparing a site for the next years planting and as a potential weed barrier in current vegetable operations.  But studies have shown that it can be attractive to insects which could harm plants or it could even create anaerobic conditions if the cardboard or paper layers stay wet for too long.  They can also cause some erosion problems and dry out the soil beneath them if they become hydrophobic which will cause the water to move across the top of the mulch and not infiltrate through it. 

My Take on Paper & Cardboard Mulch

Like I said above I like the use of this mulch in prepping a site for planting in the following year but the jury is still out on whether it makes an effective weed barrier in an existing operation.  I am currently conducting an experiment in my garden using cardboard as a weed barrier/mulch and am posting the results to my blog under the Gardening tab.  I hope you will join me there and follow along as I discover how well cardboard works as a weed barrier.

Thank you all for your time and I hope this article helps you decide what type of mulch you would like use in your garden whether you be growing vegetables, flowers or doing landscape plantings.


Garden Plot with Cardboard Mulch

Cardboard Mulching
Credit: Personal Photo