Sheet Mulcing Tip
Sheet Mulching is...
...a layered mulch system. It is a simple and underutilized technique for optimizing the benefits of mulch and Nurturing the soil. Sheet mulch can:
- Suppress weed growth
- Reduce labor and maintenance costs: weeds are composted in place
- Improve nutrient and water retention in the soil
- Encourage favorable soil microbial activity and worms
- Enhance soil structure
- Improve plant vigor and health, often leading to improved resistance to pests and diseases
Sheet mulching can be used either in establishing a new garden or tree planting, or to enrich existing plantings. In both cases, mulch is applied to bare soil or on top of cut or flattened weeds. New plantings are planted through the mulch, or a small area is left open to accommodate established plants and trees.
Step 1: Prepare the site. Knock down or mow existing vegetation so that it lies flat. Remove only woody or bulky plant material. The organic matter left will decay and add nutrients to the soil. Add amendments to this layer if a soil analysis indicates the need for adjustment of pH or minerals.
Optional: "jump start" the decay of weeds and grass by adding compost or manure at the rate of about 50 lbs/100 square feet. Soak the area with water to start the natural process of decomposition. It is much easier to soak the ground now, before the remaining layers of mulch are applied.
Step 2: Add a weed barrier.
The next step in sheet mulching is to put down an organic weed barrier that breaks down with time. It is essential that the barrier is permeable to water and air. Plastic mulches are not recommended. |
Recycled cardboard, a thick layer of newspaper, burlap bags or old carpets of natural fiber work well. Many paper companies offer recycled cardboard or paper in rolls of varying widths. Two or three layers may be required to achieve an adequate thickness. If the weed barrier is applied too thickly, the soil can become anaerobic. Overlap the pieces of the material 6-8" to completely cover the ground without any breaks, except where there are established plants you want to save. Leave a generous opening for air circulation around the root crown. Wet down the cardboard or paper barrier to keep it in place.
Step 3: Layer mulch and compost. The top dressing mimics the newly fallen organic matter of the forest. It must be free of weed seeds. Good materials for this layer include chipped plant debris, tree prunings, leaves or straw. Well decomposed, weed-free compost is also a good material but it should be spread directly over the weed barrier and covered with bulkier materials such as tree prunings, to optimize weed control. In total, the compost/mulch layer should be 3-5 inches deep. Many materials suitable for the top layer often have an attractive appearance, making sheet mulch a versatile practice.
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Step 4: Plant. Punch a hole in the cardboard and place plants in the soil under the sheet mulch. Smaller plants can often be planted right into the mulch/compost layer. Add a small amount of compost around the rootball if compost has not been included in the top layer. In most cases, the benefits of sheet mulching outweigh the costs. However, take care to prevent these potential problems:
- As with any mulch, do not pile materials up against the trunks or stems of plants to prevent disease.
- Especially during the dry season, snails and slugs will be attracted to the sheet mulch and can damage small seedlings.
- Rodents can find a cozy home in mulch and can readily debark certain trees. Protect young trees with physical guards.
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