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  • Wayne Cardinalli

Planning a new garden? Start now - remove grass by smothering

by Wayne Cardinalli

If you plan to plant a pollinator garden next spring, you can take some action in the fall. Decide where you want your garden. How much sun or shade will plants get? Will it the area be large or small? What type of soil do you have? You will need to remove existing vegetation - the lawn and all weeds must be eradicated.

You can save yourself some hard work by smothering your turf now rather than digging it up. This is called sheet mulching.

Late fall is the perfect time to start. During summer drought most lawns go dormant, so it’s better to sheet mulch when the grasses are alive. The idea is to eliminate your lawn by preventing its active growth. The lack of light stops the process of photosynthesis which helps the smothered grass die back. At the same time, worms, bugs and other beneficial micro-organisms break down the organic matter into your soil so it will be available to your plants. When the grass dies, you can plant right into the mulched area, without removing the smothering materials.



Sheet mulching steps
  1. Cut your lawn as low as possible. throw grass clippings back on lawn. Remove all deep-rooted weeds (thistle, bindweed, etc).

  2. Ensure good drainage by loosening the soil underneath the bed area with a spading fork.

  3. Water thoroughly right away. Moisture is essential to the composting process.

  4. Cover the planting area with overlapping newspaper (15-20 layers, black & white print only – no glossy inserts) or one layer of corrugated cardboard. Do not use coated or waxed cardboard, as it will not decompose. Remove staples and tape. Use the largest size boxes you can find.

  5. Dampen the newspaper or cardboard as it is laid down to protect your layering work from disruption by wind. Overlap the edges by at least 6” to prevent weeds and grasses from weaving their way through. When it eventually breaks down, the newspaper or cardboard will add carbon back into the soil.

  6. Water again until the newspaper/cardboard is soggy all the way through

  7. Add a layer of an inch or two of compost - this can be chopped leaves, composted manure, mushroom compost, homemade yard waste compost.

  8. Finally, add a layer of 4 to 6 inches of mulch. Wood chips and/or shredded bark work well.

  9. Allow 6 - 8 weeks for the grass under the paper/cardboard & compost layers to die back.

  10. Keep your new ‘compost area’ watered well. It should always have the consistency of a damp sponge.

  11. Be patient! The longer you allow the decomposition process to take place, the better results you will see.

Pros and Cons of sheet mulching
  • Why people love it:

It’s easy, involves minimal labor, and doesn’t require you to dig up your old lawn.

It’s cheap! You don’t have to haul your old lawn away to the landfill.

This method leaves all original organic matter in place, doesn’t disrupt existing soil structure,

and also adds organic matter to the soil!

Grass becomes soil-improving compost, and at the same time creates air pockets in the soil.

  • Why some people don’t prefer it:

It takes a fairly long time, so patience is key.

This is not a practical application for steep slopes, which need sod removed by hand in spring.


References:


Create New Garden Beds with Sheet Composting and Sheet Mulching - https://extension.psu.edu/create-new-garden-beds-with-sheet-composting-and-sheet-mulching


For those with concerns about ecological impact of newspaper and cardboard on soil health:

Sheet Mulching (Lasagna Gardening) – Does It Harm Soil? by Robert Pavlis - https://www.gardenmyths.com/sheet-mulching-lasagna-gardening-harm-soil/







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