The mulch question for organic gardeners is not, "If?" but "What kind?" and "How often?" Choose from more than a dozen types of landscape mulch for weed control.
When applied to mulch, the term “organic” has dual meanings: either the mulch is free of toxic chemicals, or it’s composed of something that was once alive, such as decomposed plant material. One thing all experienced organic gardeners can agree on is that mulch is essential in the garden. Mulch suppresses weeds, controls erosion, retains soil moisture, moderates soil temperatures, and enriches the soil when it breaks down.
Some gardeners choose their mulch based on ease and availability. For example, if your area is rich in pine trees, their dropped needles yield free mulch. If you live near a brewery, you might trade fresh vegetables with the brew master for some spent hops to cover and enrich the soil. Your utility company might offer wood chips by the truckload to their customers, if you’re willing to hazard the occasional ground up poison ivy vine in your delivery.
Consider one of the following mulch alternatives for the organic garden. These choices include mulches that are expensive, cheap, or free; beautiful or homely; and common or unusual. There is no single best mulch; experiment with a range of materials until you find the one that complements your gardening style.
Aluminum Foil
- Increases sunlight in cloudy areas
- Useful for houseplants spending the winter on a dim sill
- Repels some insects
- Speeds the ripening of fruits and vegetables
Bark or Wood Chips
- Inexpensive and readily available
- Breaks down slowly, so lasts through the season
- Appealing in gardens with high visibility due to uniform appearance
- Don’t mix it into the soil, as it ties up nitrogen
Buckwheat
- Expensive but richly colored
- Can blow away in exposed areas
Carpet
- Useful for permanent paths between garden rows
- Use wool or cotton carpet to prevent chemicals from leaching into the soil
Cardboard
- Cheap and plentiful
- Cover with wood chips to improve appearance
- Pierce with garden fork to reduce water runoff
Cocoa Shells
- Have an appealing chocolate aroma
- More costly than most bagged mulches
- Toxic if consumed by dogs
Compost
- One of the best soil-enrichment agents
- Must be replenished frequently
- Can serve as mulch before fully decomposing
Grass Clippings
- Adds nitrogen back to the soil
- Use a thin layer to prevent matting
- Best source of grass clippings is organically grown lawns
Hay or Straw
- Cheap or free
- Can harbor weed seeds
- May attract rodents seeking winter shelter
Leaves
- Can use shredded leaves or leaf mold
- Allow raked leaves to decompose for one season to prevent matting
Paper
- Use non-slick newspaper
- Mix shredded paper with grass clippings or coffee grounds to prevent caking
- Lay a thick layer of paper between garden rows for long-term weed suppression
Pine Needles
- Acidifies soil for blueberries, azaleas, and hydrangeas
- Breaks down slowly
Rocks
- Good choice for alpine plants
- Does not enrich the soil
- Gardeners must deal with weeds that pop up between rocks
- Rock or gravel mulches are a nuisance when they migrate into the lawn or nestle into the soil
Sources:
Cornell University Department of Horticulture
