Mulch in Your Vegetable Garden—Beyond the Basics

By on April 29, 2013

Tricia takes the mystery out of mulching; we filmed our mulching video in her raised bed vegetable garden.

Everyone tells you to mulch your vegetable garden—but exactly how should you choose a mulch?

In our video, Tricia shows you the basics of mulching.

What’s the difference between compost and mulch?

compost in a vegetable bed

That was a trick question. You can use compost as a mulch all by itself. But you shouldn’t.

Finished compost or “humus” is a cornerstone of organic gardening. In the photo above you can see Tricia spreading it in a raised bed. Compost is decomposed organic matter full of microorganisms that will populate the soil and expand the soil food web in your garden. The compost will also improve your soil quality and structure—in clay soil it increases drainage, and in sandy soil it helps retain water.

Compost feeds your soil and mulch protects your soil.

You can use compost alone as a mulch, but it will sink into the soil pretty rapidly.

What we think of as a “best practice” is to spread a one inch layer of compost and then cover it with a two inch layer of natural mulch like straw (not hay that has seeds), paper, bark, wood chips, dry grass clippings—or with a layer of plastic mulch.

Some gardeners worry that those layers of compost and natural mulch will keep water from reaching the roots of their plants. Not true. Even with our preferred drip irrigation, the water will trickle in and, importantly, will evaporate much more slowly because of the mulch layer.

When to use plastic mulch

Be sure to put the plastic mulch on top of the irrigation (or it will block water flow to the soil).

Plastic mulch is—plastic—and therefore an effective weed barrier. That’s a good thing in the vegetable garden. From the strawberry plants that are hard to weed between, to the big vegetable leaves that conceal weeds, you can see how it would be handy.

Plus, certain plants like certain colors of plastic mulch. Really.

How to choose from the rainbow of colors in plastic mulch

red plastic mulch film
Who’s rockin’ the red plastic mulch?

The strawberries and the tomatoes, that’s who. Eggplants too. Tomatoes and eggplants do 12% better with red mulch. If you don’t want to go the whole red plastic film route with your tomatoes you can take a shortcut with a red plastic Tomato Crater for each plant.

silver mulch film
Silver mulch film reflects well on certain vegetables

Aphids don’t like silver mulch film. Which means the rest of us do like it.

Use silver mulch film with your peppers and, according to Pennsylvania State University Extension, you can expect a 20% increase in size and yield.

Black plastic mulch to heat things up

Potatoes respond to all mulch colors, but they produce at their highest quality with black plastic mulch.

Are you growing onions? They’re broad-minded and respond to all of these colored plastic mulches.

Two big no-nos in mulching

volcano mulching tree
1.  For our first item on the DON’T list, let’s step outside the vegetable garden and get a vivid example of “volcano” mulching around a tree.

See that mound of mulch? Not unlike a volcano? It’s a bad idea, and for some reason has become popular around the U.S. One of the worst of the many bad consequences of volcano mulching is excess moisture around the tree trunk, which can lead to fungal canker diseases.

Friends don’t let friends volcano mulch a tree. Keep mulch at least six inches away from the tree trunk, and don’t pile it up deeper than two inches.

mulch and stems
2.  Now we’re back in the strawberry bed and it’s easy to remember, in this smaller venue, not to volcano mulch the strawberries or vegetables either. Keep all mulch one to two inches away from the stems of vegetables and soft fruits.

Those are your pointers on mulching. Now get out there and mulch! You’ll save yourself from endless weeding and watering.

  Comments (14)


I like the term “volcano mulching” .  Consider changing the no-no to “mountain mulching”.  Volcanos have a hole in the center, to give the trunk/plant breathing space.  Mountain mulching has no hole.

Posted by April on May. 04, 2013 at 2:06:18 AM

April, Excellent point! We did not coin the phrase “volcano mulching” though and it is now a popular, national term to describe the strange and terrible practice of over mulching trees.

Posted by on May. 04, 2013 at 8:54:57 AM


Oops! I have done this to my trees near my garden. I was only mimicking what the “professional” landscapers do in our area. I will remedy the situation tomorrow. Embarassing!

Posted by Brian Kulis on May. 05, 2013 at 9:15:19 PM

Brian, Don’t you hate it when the “professionals” lead us astray?

Posted by on May. 06, 2013 at 10:20:19 AM


I’m in a tropical region….can dried leaves be used as mulch? We have lots of it. Straw is not easy to get in quantity.

Posted by Bubun on May. 07, 2013 at 10:42:11 PM

Bubun, Yes, dried leaves are a good mulch. You might want to chop them up with a lawnmower or shredder so that they are fine enough that the water flows through them. A mass of large leaves could block water from reaching the soil.

Posted by on May. 08, 2013 at 10:25:18 AM


Can you use white pine needles as mulch?

Posted by Lori Harp on Jan. 16, 2014 at 3:02:01 AM

Hello Lori,
Yes, pine needles can be used as a mulch. Be aware they lower the pH so if you have alkaline loving plants, or acidic soil already they can cause a problem. For acid loving plants like blueberries and azaleas pine needle mulch is a preferred mulch.

Posted by on Jan. 21, 2014 at 8:18:56 AM


I have a terrible earwig issue in my area of South.

Posted by Tina Dibernardo on Mar. 12, 2014 at 11:34:48 AM

Hello Tina,

Earwigs can be troublesome in vegetable gardens. In yards with turf and mature ornamentals they are actually beneficial insects. This article from UC Davis has great tips for managing earwigs:

Posted by on Mar. 14, 2014 at 12:56:26 PM


I see you have plastic cones around some of your fruit trees.  To keep the mulch from the trunk?  Where can I get them and what are they called?  Thanks

Posted by Craig on Jul. 01, 2014 at 9:34:59 PM

Hello Craig,

Yes, they’re called tree guards. They do keep the mulch from the trunks. They also protect the tree from damage by weed whackers or rabbits. We sell them on our site:

Posted by on Jul. 02, 2014 at 10:36:12 AM


Hi there, I live in the Bay Area and my ‘yard’ is completely covered in about 4 inches of rough chopped mulch from local trees and such.  (We did this because we let the yard die due to water restrictions.) Do you think I could build and grow a raised bed garden on top of the mulch?  My only other option is building raised beds on top of concrete.

Posted by Autumn on Oct. 26, 2014 at 11:40:43 PM

Yes, you can put your raised beds on top of the mulch. I would suggest putting down some weed fabric to discourage weed growth.

Posted by Suzanne at Peaceful Valley on Oct. 28, 2014 at 3:42:04 PM

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