Sheet mulching for the win!

Amanda here reporting from our second glorious rainy day of this fall.  I hope you were able to get a good harvest in before the rains- as I type this my house is filled with the sweet smell of roasting tomatoes which will become a bright sauce for the winter.  (In case you’re wondering, I’m going to freeze it- not can it).

As the seasons turn yet again, I have to say that fall is my favorite.  There’s something about the light changing and the shifting that makes me go into squirrel mode.  I’ve been drying pears, making pickles and harvesting herbs and it’s so satisfying!  And, of course, I’ve been thinking about next season, too.

One of the questions I get a lot from friends who are new to gardening is how to turn previously fallow land into garden space.  Some people tarp the area over the winter to deprive the grass (or vinca or whatever vegetation you’re trying to smother) of light.  While this is one option, often it’s hard to find plastic that won’t degrade and we can all agree less plastic is always a good thing!

So, onto my favorite permaculture trick: Sheet mulching.

Sheet mulching is essentially using sheets of cardboard and/or paper to smother out grasses and lets worms and biology do the work of making new garden space over time.  Hot tip: if you decide to sheet mulch and there’s no rain the forecast, wet all the cardboard down and moisten the whole thing at the end to get it activated.


The basic process goes like this:

  1. Identify the area you want to cover and how big it is. Sheet mulching is actually pretty resource intensive with all the organic matter, so start small!
  2. Mow or weed whack it down to the ground.  Depending on how much organic matter you have cut down, you can either leave it in place or put it on top of the cardboard.
  3. Procure all your materials: Large swaths of cardboard, old newspaper if you want, biodegradable fabric or wool rugs, compost or manure and straw or fallen leaves.  Some people use wood chips but I prefer not to for veggie garden spaces.  Wood chips take a long time to breakdown and are acidic.  Our foothill soils are naturally acidic- so unless you are planting something like blueberries or fruit trees that don’t mind acidity- stick to straw or leaves.
  4. Layer one: CARDBOARD: First, put down the newspaper if you have it (don’t use the glossy parts of the newspaper- just newsprint), then the cardboard.  Remove any tape/plastic from the cardboard. You want to make sure the ground is totally covered by cardboard, so having each piece overlap by 6-8 inches or so is a good place to start.
  5. Layer two: ORGANIC MATTER: Once you have your cardboard layers down, you can add compost, manure, animal bedding, or foodscraps.  The idea is to have a rich mix of things for microorganisms and worms to feast upon.  Really get a big pile going here- up to 5 inches!
  6. Layer three: MULCH: Now that you have the foundation, it’s time to seal it in.  Mulch is going to protect your organic matter from washing away in the rains, and will also protect it from light, as well as seal in moisture to help make a great habitat for the FBI (Fungi, Bacteria and Invertebrates) who are the real workers in getting your new garden space up and running.  You want to make sure you have at least a 3 inch layer on top.  You can use rice straw (which is about $8 a bale) or you can use my favorite (free!) resource which is fallen leaves.  While your neighbors unknowingly rake up their valuable leaves conveniently into bags, you can ask them if you can take the bags away and voila- free mulch! And bonus- you get to meet your neighbors and be the weirdo who wants to take their leaves home, perfect.
  7. WAIT: Now, you wait and let nature do the rest.  In the spring, you will be able to plant right into your sheet mulched masterpiece- no tilling required!

If you want to really get into sheet mulching, check out this amazingly detailed guide or take it to the next level and make a lasagna garden (it’s pretty much the same- just more layers).

Till next month, get mulching!  (And start thinking about where you are going to plant your garlic!)

If the sheet mulching feels a little daunting and you need some help getting your garden off the ground- we’ve got you covered.  Learn more about the Sierra Gardens Program here.