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Beneficial Mulching, and Types of Mulch You Should Never Use

I am already dreaming of fall. Fall is a good time to add a fresh layer of mulch to the garden.This view of the front garden shows wood chip paths and pine straw used as mulch. Good organic mulch has many uses and benefits:

*Mulch is often beautiful and gives the garden a fresh and neat appearance.

*Mulch retains moisture around plants without making the soil soggy.

*Mulch helps to suppress weed growth.

*Mulch protects plant roots from temperature extremes in both summer and winter. 

*As it breaks down, a good organic mulch will feed worms, beneficial fungi and micro-organisms in the soil.

*The worms and other earth dwellers will pull aging mulch into the soil, improving soil texture far better than any tiller and increasing soil nutrients available for plants.

*Mulch can prevent soil erosion.

*A layer of mulch around a plant will protect trunks from mowers and weed trimmers.

*Mulch helps to prevent soil compaction from foot traffic.

*Mulch can be used to create inexpensive but lovely paths.

There are some important things to know before applying mulch.

When applying mulch around a plant, be sure to leave a "doughnut hole" around the plant's trunk. Never pile mulch in a volcano next to the trunk. Also, do not apply more than a 2-3 inch deep layer of mulch around a plant. Wider is better than thicker. Too much mulch can make water difficult to penetrate through to the soil and over time can even suffocate plant roots.

Also, never apply mulch so that it touches your house. Termites will use the mulch as a pathway to your siding.

Here are some common mulches and how to use them:

Compost:Composted organic matter provides nutrients to both plants and soil organisms. It can be incorporated into the planting hole at planting time, as well as be used as a mulch on top of the ground. Because of its fine texture, compost is not as effective at preventing weeds as some other mulches.

Wood chips and shredded bark:These are beautiful mulches. Wood chips and shredded bark make great garden paths, but fresh wood chips and bark will pull nitrogen out of the soil as it ages, possibly decreasing available nitrogen for nearby plants. Therefore, use aged bark or chips around plants, rather than fresh. For the same reason, fresh mulch should not be incorporated into planting holes.

Pine straw:This is an economical, attractive mulch. It contains compounds that inhibit seed germination, so it is great for suppressing weeds. It is acidic, so is beneficial for alkaline soil or for use around plants that like acid soil.

Newspaper and cardboard:Newspaper or cardboard will block light and suppress weeds. Cover with another type of mulch for appearance. Newspaper and cardboard is very useful when establishing a new garden. There is no need to till or tediously pull or spray old vegetation. Simply cover the area with a layer of newspaper or cardboard, wet thoroughly, then top with several inches of good garden soil and plant. Avoid newsprint with colored dyes.

Straw:Straw or hay is often used in vegetable gardens. Unfortunately, it  frequently contains weed seeds, and it provides the perfect environment for mice and voles. Its light color may not appeal to some gardeners.

Pebbles and rocks:These look most at home in a rock garden (of course!) or a desert application. Pebbles and rocks absorb heat from the sunlight during the day, then release the heat at night, so they can help protect plants during chilly nights. Water drains through easily. An edging is needed to prevent the pebbles from washing away, and weeding can be a nightmare. A layer of landscape fabric beneath the rocks will postpone the weed problem but will not prevent it. In fact, it can make the problem worse. Landscape fabric deteriorates over time and will allow weeds to take hold. Believe me, pulling weeds through the rocks and landscape fabric can make the saintliest gardener cuss, and removing old landscape fabric is not fun, either. Pebbles and rocks are probably best used in applications where the gardener can spray weeds without worrying about harming plants, such as  paths and parking areas. Forget the landscape fabric.

Dyed wood mulch:Wooden pallets and various types of wood trash are chopped up and dyed. This mulch may contain harmful chemicals, including creosote and arsenic. Rain will wash the color out of the wood, and you may see it running onto your patio or drive. Some people like the colors, but I would never use it.

Dyed rubber mulch: This stuff is made from old rubber tires. Instead of being disposed of in a toxic waste dump, the tires are shredded and dyed in an assortment of colors, packaged nicely and then sold as mulch. It stinks like petroleum in the summer and leaches pollutants into the environment. To my horror, rubber mulch is often used on playgrounds. Never put this material in your garden.

Here is another view of mulch used in my garden. It has been raining, so everything looks fresh.

Imagine what my garden would look like if all the mulched areas were bare dirt and weeds! 



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Reader Comments (23)

Hi Deb, great post about mulch! I was aware already of most of the information that you provided, but didn't know that dyed mulch is made from wooden pallets and wood trash and that it may contain harmful chemicals.
Honestly, I hate the look of rubber and dyed mulch and it would never occur to me to spread it in my garden, but unfortunately you see it often used in California.
In my garden I usually use compost as mulch, because it breaks down the fastest and feeds my soil the best. It truly has considerably improved my soil. It has been one drawback though: Although I have only a small garden it is quite expensive. I am still going back and force to buy a compost bin and try to create my own mulch. At least it would create part of the amount that I need, even though I never would be self-sufficient mulch-wise.
Wishing wonderful last summer days!
Warm regards,

August 7, 2016 | Unregistered CommenterChristina

Great information! In most of my beds, I use shredded bark mulch for the reasons you mention. For the vegetable garden, I use marsh hay. It's different than regular hay in that it's harvested from a marsh and doesn't contain the seeds that can be a problem with regular hay. Here's some info about it: marsh hay link. I also use rocks and lava rocks in many of my pots. Lava rock is a pain in the tush, but it discourages digging by squirrels and chipmunks. I wouldn't use it for a large area, but it is very effective in the pots.

August 7, 2016 | Unregistered CommenterBeth @ PlantPostings

I made the mistake of using mulch made from wood pallets once. It wasn't dyed but it still was horrible and I ended up removing it all and replacing it. I make my own compost but I never have enough so I usually order composted material from a local company now and generally spread it every spring to protect the soil from the challenges posed by too much summer heat and not enough irrigation.

August 7, 2016 | Unregistered CommenterKris P

Red dyed mulch? I wonder if there is any garden in which that would look nice. And dyed rubber mulch sounds even worse. I do like springy paths made of wood chips and shredded bark.

August 8, 2016 | Unregistered CommenterDenise

good post! My favorite mulch is pine bark fines. I also hate hate hate the rubber mulch on play grounds.

August 8, 2016 | Unregistered CommenterEvelyn

Very detailed and informative post, Deb.

I actually believe the best 'mulch' is a groundcover plant (aka 'green or living mulch') but it's hard of course to find just the right groundcover that's robust, but not too aggressive.

Meanwhile, I think shredded hardwood is probably my favorite at the moment. Seems less likely to float away in heavy rain than pine bark nuggets (which I don't think you covered).

Pine straw has its place too, I think, but I hate pulling whatever weeds do make their way through pine straw and I think pine straw has a tendency to swamp small perennials. It's probably best for large-scale plantings where it can be used among trees and shrubs.

Incidentally, if you're not supposed to put mulch next to your house, what are you supposed to put up against the foundation?

August 8, 2016 | Unregistered CommenterAaron Dalton

Hello, everyone! Thank you all for your comments!
Aaron, regarding mulching next to the foundation of a house, termites love the cool, often damp environment provided by mulches, especially when the mulch layer is thick. It is best to leave a strip of bare dirt about 6 inches wide next to the house. However, if appearance is a concern, I think a very light scatter of the mulch should not hurt, and avoid watering the area. Most people apply mulch around foundation plantings, which are usually several feet from the house, and that should be OK.
Also, pine nuggets are in the same class with the wood chips and shredded bark.
Best wishes to all! Deb

August 9, 2016 | Registered CommenterDeborah Elliott

Great post Deb, I think the rubber used in children's play areas is not made from tyres, at least not in the UK, I don't know about other countries.

August 10, 2016 | Unregistered CommenterChristina

I enjoyed reading this post. I do love a good mulch. I wish I had more compost so that I could mulch all of my borders every year. One day, maybe....
This year I tried using lawnmower clippings, spread very thinly, in the kitchen garden. (Needless to say, I don't use chemicals on my lawn). I found the clippings particularly useful under strawberries. I don't like strawberry mats and since I'm a coeliac, I'm not keen to start throwing straw around my edible plants. I am waiting to see if the clippings create increased weed issues. So far, so good.

August 10, 2016 | Unregistered CommenterSarah Shoesmith

Great stuff Deb, I couldn’t agree more, I have been preaching about my mulch for years :-)
I use only pine bark mulch in my own garden after some experimenting with gravel mulch and getting tired of the work involved – and I think bark mulch has a natural look, smell lovely and ticks all the boxes for me. The bark we get over here is ready composted (I think for about 6 months) so can go straight into the beds, and won’t affect the nitrogen level at all as long as it is not dug into the soil much. Oh, and we have no issues with termites here in Britain so we can mulch all the way to the house as long as it doesn’t cover any airbricks. I can’t imagine what my garden would look like without bark mulch – it would have LOTS of weeds!

August 10, 2016 | Unregistered CommenterHelene

Hi everyone, again! Christina, from what I read, old tires (tyres) are in fact used for rubber mulch on playgrounds in the UK, as well as the US and other countries. Rubber mulch used on playgrounds is particularly concerning because small children have a tendency to put the stuff in their mouths. The sad thing is that companies promote their product as being eco-friendly because it gets old tires out of landfills! Deb

August 10, 2016 | Registered CommenterDeborah Elliott

Very fine overview of the importance of mulch. I, too, am a believer. And what on earth possesses some people to use rubber mulch? It is an abomination. A mulch you didn't mention, that is carried by one of my favorite nurseries, is cocoa bean shells. I've used them here and there. They work well and add a faint scent of chocolate to the garden. Usually, though, I use shredded pine bark.

August 11, 2016 | Unregistered CommenterJason

Great advice about mulching. I generally use compost as a mulch, but I've recently discovered that much of the local compost (which is made primarily from cow manure and seafood waste) has a higher Ph (because of the shellfish shells) than most plants like. I'm developing ways to balance it with acidic pine straw (which I have tons of from the white pine trees that rain pine needles down on my house and garden through much of the year.

August 13, 2016 | Unregistered CommenterJean

We generally refresh the mulch here every year in June. But last year, we took a look around and thought we could skip a year. Big mistake! The weeds took over and I've been fighting them ever since. But the good part is that I had a lot of plant seedlings show up, even from plants that I didn't know you could grow from seed. Still, I'll never skip mulching again!

August 15, 2016 | Unregistered CommenterRobin

This was a wonderful post Deb! Your garden just looks amazing - so neat and tidy! I have to admit there is nothing better than seeing the garden freshly mulched - its like a freshly made bed. I like compost and bark chips the best although I have difficulty sourcing good compost and would never be able to make enough myself for the whole garden. Its getting harder to find the smaller wood chips too, as around here they seem to be these huge pieces which are so ugly. I have several neighbors who use that dyed rubber mulch - yuck it looks awful and the fact that it is poisonous is even worse. :-((

August 15, 2016 | Unregistered CommenterKate R

I use a cedar mulch on my beds. I did not know I might be depriving my plants of nitrogen. I think the shredded tires are horrifying. I know we need to find ways to reuse old tires, but use in landscaping is not the way to go. It is amazing that they put shredded tires in playgrounds!

August 18, 2016 | Unregistered CommenterJennifer

Ok , now I know more than I ever wanted to know about mulching ,lol , yest is very informative.
Like I didn't know about worms and other earth dwellers pulling aging mulch into the soil which increases soil nutrients , that's good to know. Thanks for the info.

August 20, 2016 | Unregistered CommenterPatsi

Very good post, Deb. Great for new gardeners especially. My garden is heavily planted, so shredded bark mulch is long gone from the garden. Compost is what I use, so good for the soil too.

August 20, 2016 | Unregistered CommenterDonna

speaking of termites, do you happen to know a natural way to keep them away? I have been thinking about the termite bond we get on our house and that it may be too toxic. I put it off for now. Sorry, I know this is not really a garden question ;)
LOVE your garden!!

November 20, 2016 | Unregistered CommenterBrooke

Hi Brooke, thank you for visiting my blog and for your kind comment! About termites, I have read that using borax works, as well as parasitic nematodes. Another good thing to use is neem oil.
Best wishes!

November 25, 2016 | Registered CommenterDeborah Elliott

The amount of work that went into this post astonishes me. Thank you for your honest opinion about rubber mulch since I have been looking for one for quite some time.

I planted knock out roses and bought mulch by the truckload to put in all the flower beds. It’s been less than 2 weeks and my roses are dying and also my Crape Myrtles which have been here for 25 years. Leaves on all are turning yellow with holes in them and flowers dying. Could this be from the mulch? If so, is there anything I can do to the mulch to get rid of whatever parasite it might be? Thank you for your help.

July 10, 2018 | Unregistered CommenterBrenda

Hi Brenda,
Hi Brenda,
I can imagine your distress! The fact that the leaves have holes in them does make me think it is some sort of pest. Otherwise, I would suspect that the mulch had a chemical in it that is harming your plants, or that an herbicide sprayed prior to putting in the mulch was affecting your plants' roots. Have you seen any bugs on your plants? It is certainly possible that your mulch brought in some harmful insect, or it could be coincidental. Try spraying with an insecticidal soap or a horticultural oil such as neem oil. Follow directions. if your climate is hot, be sure to spray any horticultural oil in the coolest part of the day.
Best wishes!

July 10, 2018 | Registered CommenterDeborah Elliott

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