Download DID YOU KNOW….. Sheet Mulching: No

DID YOU KNOW…..
Sheet Mulching: No-Till Garden Beds
Many gardeners like to till their garden beds on an annual basis to “fluff” up the soil and provide a
nice, open space for their plantings. While the appearance and smell may be appealing, few know that
they are actually in many cases doing more harm than good. Tilling the soil has the following nuintended consequences:
1) It breaks up soil aggregates which are a product of soil organic matter and biological activity
2) It disturbs and destroys populations of soil biology including bacteria, fungi, and earthworms.
3) It stirs up weed seeds and thus creates more work weeding the garden
4) Combined with rain events can lead to soil erosion
Sheet mulching is one strategy to remedy lifeless soil, inhibit weed growth, and mulch all at the same
time. Not surprisingly, this is a commonly used technique in Permaculture because it is easy, quick
and effective. Whether you want to start a new garden, fill a raised bed with soil or expand an
existing garden, sheet mulching is one of the easiest techniques. It’s the simple process of layering
carbon (“browns”) and nitrogen (“greens”) on top of dirt, weeds, grass, or an existing garden much
like making lasagna (sheet mulching is also known as “lasagna gardening”). This technique is best
used with veggie transplants, tree systems, and perennial beds; direct seeding is not as successful.
For more on this and other topics, you can visit:
http://blogs.cornell.edu/garden/sheet-mulching/
Image adapted from Chelsea Green Publishing.
Materials you will need:
- Weed barrier such as non-glossycardboard, newspaper, phone books, or scrap paper (the bigger
the sheets, the better)
- Compost or manure (this needs to be completely cured if you plan to plant directly into it)
- Mulch such as fallen leaves, straw, or wood chips
Steps:
1.
Let existing vegetation grow as tall as possible, or if the soil is bare sow a cover crop and allow it to grow to
12 – 24″. Mow, scythe or cut your lawn, weeds, or other vegetation right down to the ground. Leave this material
right there where you cut it (it will breakdown into new soil and feed the biology).
2.
Aerate your soil using a broadfork or a regular hard-tined garden fork. Stick in the ground and move back
and forth around the entire site you plan to mulch.
3.
Plant any crops that will require a large planting hole (including woody plants, perennials in large pots, and
large transplants).
4.
Add soil amendments if needed (as determined by your soil test).
5.
If you have compost materials that may contain weed seeds (like fresh manure, leaves, or hay), spread
them in layers on the ground. Put a dry, carbonaceous layer of hay or shredded leaves below or above this manure
layer. Avoid thick layers, and make sure to get a good carbon-to-nitrogen ratio just as if you were building
a compost pile. Water this layer well if possible.
6.
Lay down the weed barrier. Use large sheets of cardboard from appliance stores if possible, because these
last longer and are quicker to put down. You can use layers of non-glossy newspaper too. Make sure to have a 4- to
6-inch overlap where sheets meet so buried weeds can’t find a route to the surface. If you have already planted
crops, or have other preexisting plants, don’t put this barrier over them. Rather, cut holes in the cardboard/paper to
make some breathing space for each plant. A great tool for this is a hori-hori, or Japanese garden knife.
7.
Now you can add weed-free organic materials. Keep it simple and add a nice layer of compost or manure.
Or you can do some sheet composting here; alternating layers of nitrogen-rich materials (e.g. fresh grass clippings,
kitchen scraps) with carbonaceous materials (e.g. straw, leaves).
8.
Add your final top mulch layer, at least 3 inches thick. Water the whole bed thoroughly once again. Your
sheet mulch bed is complete.
9.
You can plant right into the bed you made if you like. To plant a large transplant, just pull back the top layers
until you get to the weed barrier (cardboard or newspaper). Cut an X into it, peel back the corners of the X and dig a
hole. Throw a double handful of compost in the planting hole and then put in the plant. Pull the layers and top mulch
back around the plant, water well, and you’re all set. Planting seeds is easy too. Just pull back the top mulch to the
compost layer and plant your seeds. You may want to cut through the weed barrier below first, depending on how
thick it is and weed pressure below the barrier. If you are planting seeds, be sure to water enough to keep them
moist (could once a day in hot weather), as compost on top of cardboard can dry out quickly.
Sheet mulching can be done at any time of the year, but it best done 6-12 months before you want to
garden in the space to give all the layers time to breakdown. Then the process can be repeated every
year after your garden season is over. Over time, as material builds up and you get further from the
seed layer, it may not be necessary to do the entire process.
Additional Resources:
Toby Hemenway’s “Bomb-proof” Sheet Mulch
Sheet Mulching Factsheet from University of Oregon
Sheet Mulching poor urban soils with Jonathan Bates & Eric Toensmeier
Author: Falk, Elizabeth, Steve Gabriel Cornell Garden-Based Learning, updated 3.5.14
[1] Permaculture is a design technique for landscapes including gardens, farms, homesteads, and
urban sites. Permaculture uses ecological principles based on patters found in nature. These ecological
principles combined with a design method helps to create sustainable, healthy and abundant
landscapes while also meeting basic human needs. Source: www.fingerlakespermaculture.org