Make a Lawn into Garden with Cardboard

Garden

Give up the grass!  Grow veggies instead.  Or wildflowers.  Or herbs.  Or make a butterfly garden.  Or plant fruit bushes.

In the 10 years I worked as a Landscape Gardener I got plenty of experience manually digging out sod to make garden beds.  Its not fun.  Don’t do it unless the area you’re digging out is small.  Strips of sod are heavy and it is back breaking work.

If you have the budget and enjoy machinery you could rent a sod-digger to take out the grass.  However, sod-diggers are heavy and handle like elephants.  Plus, you still have to carry and dispose of the strips of sod somehow.

The Cardboard Method is less back breaking and it feeds nutrients back into the soil.  In essence, the grass gets covered with cardboard for a few months which causes the sod to decompose.  Once the grass is decomposed the cardboard and grass (and its roots) can be turned back into the soil.  The length of time it will take to decompose depends on your climate:  temperature and moisture will determine decomposition time.

This method can be started at any time of year.  Starting it in the spring, rather than fall, will result in faster decomposition of the sod and the process won’t take as long.

Steps

1)    Decide which area of your lawn you want to make into a garden (whether its a veggie garden, herb garden, flower garden, or wildflower garden, etc).

2)    Mark out the area using string or a shovel or a hose.

The neglected garden area at my new acreage overgrown with grass and weeds.

3)    Collect enough cardboard to cover the area.  Choose cardboard that has minimal writing, pictures, and dyes on it.  A little bit of dye is okay but any paint on the cardboard will either flake or seep into your soil.  Make sure the cardboard is mostly a brown colour, not white, or black, or something else.  Remove staples or tape or plastic that is stuck to the cardboard.  Anything you leave on will end up in your soil.

4)   Collect an organic mulch covering for your cardboard.  This step is optional.  The method will work with just cardboard.  When you add decomposed organic matter on top of the cardboard, it will add even more nutrients to your garden when its dug into the soil later on.

Choices include:

  • Well-rotted manure
  • Decomposed compost
  • Peat Moss
  • Loam

Its important that any plant material you use as mulch on top of the cardboard be decomposed.  If you dig non-decomposed mulch, such as leaves or grass, into the soil, it will not add nutrients.  As the non-decomposed dug-in grass and leaves decompose they may sap nutrients from the soil in the decomposition process and this will not help your plants to grow.  Also ensure that your mulch has no pesticides or herbicides in it as they will damage your plants.

Note:  In the photo below with Step 9 you will see that I’ve used some partially decomposed grass and leaves on top of the cardboard – I’m okay with that because the climate and moisture levels here over the winter are high and will cause the grass and leaves to decompose enough over the winter.  I put the cardboard down in October and will dig the garden in April.  Six months plus lots of wet snow plus a relatively mild winter here (average temps between –3 to +1 degrees) will ensure sufficient decomposition of the grass and leaves.

5)  Mow the grass low.   The shorter the grass the easier it will be to dig in later.

The garden area weed-wacked low to the ground with the long grass and weeds raked off.

6)  Rake off any long pieces of grass or tough weeds and compost them.

7)  Cover the area with cardboard.  Make sure there is an overlap of 3-6 inches with each piece of cardboard – grass and weeds will grow through any gaps or cracks.

Cardboard covering the areas where the grass grew in to the garden beds. Cardboard overlaps 3-6 inches. The area around the tree has no grass to be covered.

Garden

8)  Optional:  Cover the cardboard with decomposed mulch 1-6 inches thick.  The depth of the mulch mostly depends on how much you have.  The more mulch, the more your soil will be enriched.  If you have really poor soil, I recommend using a deeper thickness of mulch.

Cardboard covered with the remains of an old bag of peat moss that was in the shed.

9)  Water the cardboard thoroughly.  If you live in a climate with alot of moisture and you’re leaving the cardboard for more than 4 months you don’t need to water the cardboard.  If you live in a windy, dry climate its crucial that you water the cardboard so it decomposes sufficiently and doesn’t blow away.

The cardboard covered with as much partially decomposed leaves and grass as I had on hand. The uncovered cardboard will still do its job.

10)  Let Mother Nature take its course.  Leave the cardboard for 2-6 months.  In warmer moister climates the process won’t take as long.   In colder dryer climates the process will take longer.

11)  When the sod and cardboard are rotted you can dig everything in.  Mix the rotted cardboard and sod into the soil thoroughly.  Rake it smooth.  Plant your seeds!