Let's answer some questions about using mulch in the garden, including the pros and cons, types of mulches, which mulches work best for both vegetable and flower gardens, and my all-time favorite weed suppressing technique that uses two kinds of mulch.
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I'm a big fan of using mulch in the garden. One of our most popular videos is how we use mulches to have (almost) weed-free flower beds.
And the no-till vegetable method I use needs mulches like compost, leaves, and straw, to name a few.
So in answer to the question, "Is mulch good for a garden?" you can probably guess what I think!
Mulching garden beds and pathways is probably the number one thing that has made gardening actually doable without the hours of work I saw people putting into their gardens growing up.
But there are a lot of other questions about garden mulch - What is it? How to use it? What type is best? - that gardeners have asked over the years.
They are all good questions, so in this article, we're going to:
- Define what mulch is.
- Look at the pros and cons of mulch.
- List the different types of mulch (and which last the longest).
- Discuss which mulches are best for different parts of the garden.
- Go over how to use mulches in the garden and best practices.
I hope this resource answers some of your questions about using mulch in the garden - if not, be sure to leave a comment and ask yours!
Using Mulch In The Garden
Let's start with the most basic question:
What is mulch?
The Merriam-Webster definition is:
: a protective covering (as of sawdust, compost, or paper) spread or left on the ground to reduce evaporation, maintain even soil temperature, prevent erosion, control weeds, enrich the soil, or keep fruit (such as strawberries) clean.
I would add to this, except it covers it perfectly! These are all the reasons I use mulch in the garden, though controlling weeds and maintaining even soil moisture are my top two reasons.
Now that we know what mulch is, let's move on to more specific questions.
What is mulch made of?
There are a lot of different materials that can be used as garden mulch:
- grass clippings
- hay and/or straw
- shredded bark or wood chips
- animal manure
- pine needles/straw
- plastic/landscape fabric
Even though these are all considered mulches, not all are good as a TOP mulch - the kind I like for helping hold down weeds and keep the soil moist.
Cardboard, paper and manure are all best as layering mulches while straw, wood chips and compost work as top layers (though compost can be a bottom layer as well - more on that below).
Pros & Cons of Using Mulch in the Garden
Pros: What is mulch good for?
- Mulches help retain moisture in the soil.
- They work to suppress weeds.
- They keep the soil cool and evenly moist.
- They can prevent frost heaving in winter.
- They make the garden look more attractive.
- Organic mulches help improve the soil's structure, drainage, and nutrient-holding capacity as they decompose.
Cons: When can mulch cause problems?
There are mainly two ways that mulch may hurt the garden or plants:
- Over-mulching plants roots can bury and suffocate plants. In addition, researchers have discovered that excessive amounts of hardwood mulch cause manganese and other elements to build up to levels that are toxic to plants. This is why I prefer feeding mulches like compost.
- Mulch can provide hiding places for pests.
Also, if you lay mulch over dry soil and don't plan for root-level watering (like a drip system or soaker hoses), you could lose plants to lack of water.
In my experience, the benefits far outweigh the potential problems, especially when you can fix them with appropriate application.
Which mulch is the best?
Well, it depends.
If you live in dry climates, you'll have less weeds to deal with and can use mulches mainly for looks and conserving moisture. You won't want mulches that dry out and may blow away like straws or leaves. It's better to look at rocks, shells, or larger wood chips.
If you live in mild, moist areas (hand raised), you'll need to use mulches that cover completely because weeds will come up in every nook and crannie left open.
Even then, your yard may have different microclimates and you may find that different mulches work in different areas:
- Dry and shady? Lay newspaper and a compost or leaf mulch to feed the soil and conserve water.
- Moist and shady? Use cardboard and medium wood chips so that weeds don't have a nice place to take root.
- Hot sun all day? Lay newspaper and compost or pine needles or straw to help hold in the moisture.
- Windy area? You'll want a mulch that won't blow away when dry like wood chips, shells, or rocks.
That being said, I do have my favorite top mulches that both look good and work well.
My favorite all-time mulch that I've used for years in flower beds is basic garden compost you can get at any landscape company.
It's inexpensive, is a dark color that looks wonderful in the garden, and actually feeds the soil as it breaks down.
When you use compost as a top mulch in beds and borders, you won't need to fertilize your shrubs and perennials ever.
Really! The lush flower bed above was only given a yearly (or every other year) 2-inch layer of garden compost and no other fertilizers. The plants bloomed and grew like this every single year.
However, I have learned that garden compost as a top layer is not for everywhere.
If you have a shady, moist area, the weeds will take root in the fertile ground of the compost even as it is suppressing weeds from below.
Also, if you garden next to fields or neighbors with lots of weeds, you'll get blown-in weeds that will love the nice topping.
In these cases, I suggest a 1-inch layer of garden compost to feed the soil, followed by newspaper or cardboard and then a 2-inch layer of wood chips, pine straw, or other type of mulch that will discourage blown-in weeds from rooting.
Shredded bark vs. wood chips as mulch:
Wood chips are larger and chunkier than bark mulch, providing a cleaner ground cover than smaller shredded bark while discouraging weeds from rooting.
The free wood chips/shredded bark you can get from some communities and tree care companies is a great resource for mulch, but the size of the pieces are all over the place, so I use this only for pathways.
Which mulch lasts the longest?
Cedar wood chips is one of the longest-lasting organic mulches.
While more expensive than other mulches, cedar chips last longer because it's naturally resistant to decay (bonus: it's oils naturally repel insects, too).
However, because this mulch is long lasting, it won't provide much nutritional benefit to the soil beneath it. You will need to supplement shrubs and perennials with fertilizer.
Thick, black plastic is one of the longest lasting inorganic mulches when covered with rocks or chips to block the sun damage. I don't recommend this for long-term planting areas, though, as the barrier will deplete the soil of nutrients.
What about landscape fabric?
I have a hate-hate relationship with landscape fabric that's sold in stores as a "professional weed control."
After having pulled up yards and yards of weed-infested landscape fabric from our last two homes, I beg people in climates that have lots of grasses and weeds to NOT use it!
In the photo above, I'm removing our farmhouse's last owners "permanent" mulch of landscape fabric and rocks since the weeds had taken over.
Once the roots are in the fabric there is NO weeding them out. Your only choice at that point is to spray them continually with weed killer (no thank you) or to remove it.
You will also notice that the soil uncovered is compacted and depleted. It works that way like solid plastic, even though it has holes to allow water through.
When Should I Put Mulch on My Garden?
While the best time to mulch both flower and vegetable gardens is in the spring, I've found mulching anytime you can is better than not at all.
Sometimes it took until August to complete the mulching of our previous cottage's extensive flower beds. I just watered well before covering the beds to make sure not to bake the beds.
Using soaker hoses or other root-centric watering systems will make this easier, too - the water will always be able to get to the roots that way without having to penetrate the mulch.
If you live in cold climates, mulching in the fall could be a way to help regulate the freeze-and-thaw cycles.
So the real answer to when should you mulch your garden is: whenever you can!
How to Mulch Your Flower Garden
Flower Gardens, Beds, and Borders
There are a couple ways you can go about mulching your flower garden.
The first is to weed the area completely, then lay down a 3 to 4-inch layer of mulch. If it's a shady area, you may be able to get away with 2 to 3-inches.
Depending on where you live, this may be all you need. Drier climates have less weeds. Urban settings have less weeds blowing in from neighboring fields.
However, if you live in a place like me - moist much of the year where weeds and grasses grow out of control - the thought of spending hours weeding may make you want to give up on gardening all together.
This is where the my favorite paper-mulch combo comes in to save the day.
Simply remove the largest, perennial weeds (dandelions, clover, violets, etc.) leaving all the tiny annual weeds and grasses.
Then simply layer 5 to 10 page sections of newspaper on moist soil (water first if soil is dry), under the soaker hose or drip system, and cover with 2-3 inches of compost or other mulch.
Do this every year and you should have less and less weeds to deal with unless they blow in from surrounding areas. Even if weeds do blow in, they are easy to pull since they are rooted in the loose mulch.
This is all you need to do for your bed for the year - no fertilizer or constant weeding. You can concentrate on watering, deadheading, and enjoying your flowers.
When to Use Cardboard vs. Newspaper + Mulch
Use cardboard in areas you will not want to plant anything through out the season or where you don't have bulbs coming up.
Cardboard takes longer to breakdown than newspaper, so you will have a harder time cutting through it to plant as well as making it hard for bulbs to come up.
Also if your climate is drier, go with newspaper as cardboard creates more of a water-barrier than paper.
Safety of Using Newsprint and Cardboard in Organic Gardens
The main sections of newspapers are printed with soy-based ink and so are approved for organic gardens. Avoid colored and glossy pages. (source)
In addition, "the use of brown cardboard as mulch is very effective as a weed barrier and that it biodegrades and does not appear to pose any substantial threat to the health of the soil and soil organisms." (source)
Flower, Shrub & Tree Mulching Tips
Mulches that also retain moisture like wood chips can slow soil warming. In spring, pull mulch away from perennials and bulbs for faster growth.
A wet mulch piled against the stems of flowers and vegetables can cause them to rot so keep mulch about an inch away from crowns and stems.
Likewise, mulch piled up the stems of shrubs and trees can also cause rot as well as provide nesting areas for. Keep deep mulch pulled back about six to 12 inches from established trunks.
How to Use Mulch in Your Vegetable Garden
Is it OK to use mulch in a vegetable garden?
Well, I wrote a whole book on vegetable gardening the easy way, and one of my biggest easy-care gardening techniques is to mulch permanent paths with wood chips, gravel or straw and to use permanent raised beds.
I've found it is THE way to cut down on your weeding. So, yes!
In addition, using organic mulches like straw, grass clippings, weeds, and compost around the vegetables will keep down weeds, help keep moisture levels even, and feed the soil as it breaks down.
However, unlike shrubs and perennials, you will need to fertilize vegetables even when mulched with a good organic topping. Veggies grow fast and fruit quickly in comparison and so need more feeding.
The one place I do use black plastic in the vegetable garden (and also to kill weedy areas to start new planting beds) is as solar weed killers.
I cover beds with the plastic 3-4 months before I want to plant and it will kill everything underneath so I can plant in a weed-free bed. See more on how this works here.
I also use red plastic when planting tomatoes and sometimes peppers - studies have shown that the plants produce more fruit that way and our short season needs all the help it can get.
Here's more on using mulches and compost in vegetables gardens:
- Planting A Garden Bed The No-Till Way = Fewer Weeds
- 9 Simple Steps to Your Easiest Garden Ever (+Printable Checklist!)
- How To Plant Corn Weed Free (Really!)
- Planting Potatoes The Easy Way with Straw (+ Updates)
A favorite book on using mulches in the vegetable garden is Ruth Stout's Gardening Without Work. Now there's someone who uses mulch!
One last question:
Should I remove old mulch?
Do not spend time removing last year's organic mulch! (Landscape fabric and plastic is a different matter...)
As we've seen, organic mulches gradually break down adding beneficial nutrients and other organic matter to the soil.
When you're down to an inch of mulch, top off the old layer with an additional inch or two of new mulch to keep it at its optimum level.
So, tell me - did I answer all your questions about mulch? And if you use mulch in your garden, leave a comment with what works best for you!Disclosure: affiliate links in this article will earn commission based on sales, but it doesn't change your price. Click here to read our full disclaimer and advertising disclosure.