Fall brings a flurry of homeowners and landscape companies adding mulch to trees and shrubs, perennial borders, annual flower beds, and vegetable gardens. At the same time, leaves are bagged or sucked up to be transported to some unknown end. Spring brings more mulching.
What is mulch?
Mulch is any organic or non-organic material you apply on the soil surface to enhance plants’ growing environment. Soil amendments differ from mulch because you dig or till them into the soil.
Organic mulches:
- Living or green mulches: Low-growing carpet-like plants underneath taller plants.
- Pine or grain straw: Widely used in low traffic areas. Grain straw is used in transitional and vegetable areas.
- Grass clippings and leaves: Volume and texture varies with shredding.
- Newspaper and cardboard: Heavy layers block weed growth, but also reduce the penetration of moisture and air and restrict soil life, such as earthworms.
- Compost: Adds nutrients and organic matter in small amounts. Use with other organic materials.
- Arborist wood chips: Aged chips provide some advantages to “fresh” chips, but both work well. As with other mulches, do not “dig in.”
- Bark mulches: The most common commercial mulches are bagged or delivered in bulk. Quality of bark mulches can be inconsistent.
- Sawdust: Not recommended because it can create a barrier to water penetration.
Non-organic mulches:
- Rubber mulches: Last longer than organic mulches, but may be toxic to the environment.
- Gravel and crushed rock: Often used as a design feature or for walkways, but may create too warm an environment for plants and can be difficult to weed.
- Solid plastic sheeting: Specialty uses in vegetable gardens, but not recommended for landscape beds because water penetration is an issue. Most are not biodegradable.
- Other landscape fabrics: Woven fabrics can allow water to pass through, but also can be problematic over the long term.
Why mulch?
In addition to reducing your gardening workload, properly applied mulch offers many benefits:
- Saves water because mulch-covered soil stays moist longer and needs less irrigation.
- Moderates soil temperature.
- Controls weeds since fewer weeds germinate in covered soil.
- Reduces soil erosion.
- Adds organic matter and nutrients to the soil in small quantities.
- Makes garden beds neater.
- Reduces water splatter that carries soil-borne diseases.
- Reduces soil compaction from rain.
- Helps keep mowers and weed-cutters away from the trunks of trees.
There is a downside . . .
- Mulching can be expensive.
- Mulches deteriorate over time, are washed away in heavy rainfall, and are scattered by foot or vehicle traffic.
Application guidelines
- Use what you have: grass clippings, wood chips, leaves—compost or grind before application for great results.
- Arborist wood chips from tree work are often available for free.
- Check the origins of other mulch materials. Some may be dyed or contain contaminated wood. Look for local forest products.
- Apply enough, but not too much! Mulching with 3 to 4 inches of most materials is sufficient. Use at least 6 inches of wood chips for weed suppression.
- Keep mulch away from tree trunks and plant stems. “Volcano” mulch can cause damage to trunks or stems and cause improper root growth.
Bottom line
Enhance your landscape with proper mulching. You can create a richer and more efficient landscape using mulches!
Article written by James Wade, Extension Master GardenerSM Volunteer.
Learn more
Mulch
by Clemson Cooperative Extension
Mulching the home landscape
by Susan H. Barrott
University of Minnesota Extension