Article On Mulch . . . .

From the Morton Arboretum:

What makes good mulch?

Several factors should be considered when choosing mulch:

Texture. Medium-textured mulch is best. Fine particles tend to pack down and retain moisture, which then evaporates before reaching plant roots. Coarse-textured materials may be too porous to hold adequate amounts of water.
Nutrient value. Organic mulch provides nutrient- rich humus as it decomposes. This also improves soil structure.
Availability. Consider the availability of different mulch material and whether you have to haul it yourself. Bulk materials may be available free from your community.
Aesthetics. The type of mulch used is a personal preference. Choose for yourself the look you desire. The Morton Arboretum uses organic mulches because of their many plant benefits. Ideally, organic mulch should be composted or otherwise treated before use so that weed seeds, insects, and disease microorganisms are killed. Composted mulch generally has more uniform texture than mulch that is not composted. Composting is probably not needed for disease and insect control if the mulch is derived from healthy plants; however, if it has been sitting outside indefinitely it is likely that weed seeds are present.

TYPES OF ORGANIC MULCH:

Grass Clippings. Dry or compost before using. Mix with other materials to increase porosity and reduce matting. A source for some nitrogen but also higher alkalinity, which may compromise nutrition.
Hardwood Bark. Pine bark or shredded bark, can be purchased as bags of small or large chips. Long-lasting.
Hardwood Chips. Readily available and often free from municipal sources. If chips are not composted, apply a nitrogen fertilizer at a rate of 1/2 pound/100 square feet of chips.
Composted Leaf Litter (leaf mold). A good source of nutrients but may increase weeds if not thoroughly composted.
Animal Manure. A good source of nutrients. Compost before applying or plant damage (burn) may result due to high salt content. Ideally, should be mixed with a coarse-textured material..
Mushroom compost. A good source of nutrients when mixed with other materials. Source of large amounts of alkalinity and sometimes salts.
Peat Moss. Compacts easily due to fine texture and dries out quickly. Not recommended as a top dressing because water will not penetrate when dry.
Pine Boughs. This is a good covering for perennials in the winter.
Pine Needles. Not widely available and should be mixed with other materials unless soil acidity is desired.
Sawdust. Compost first or mix with a nitrogen source (manure and/or fertilizer) before applying. Oak sawdust helps acidify soil and is good for azaleas, rhododendrons, and blueberries. Do not use sawdust from treated lumber.
Sewage Sludge. A good source of nutrients. Composted sludge is available commercially (i.e., Milorganite or Nutricomp) and should be incorporated with soil or mixed with other composted material.
Shredded Leaves. Leaves are variable in texture and can be collected and shredded at home. Mix into the soil in the fall and allow to break down naturally during the winter for improved soil quality.
Straw. Coarse-textured so it persists a long time, but can blow away easily unless mixed with other materials. Generally not suitable as a landscape mulch, but provides winter protection and cover for grass seed.

APPLYING MULCH

• Spread mulch under trees, shrubs, and throughout planting beds to a recommended depth of 3-4 inches for medium to coarsetextured materials.
• Pull mulch away from the bases of tree and shrub trunks creating a donut-hole. Do not pile it up against the trunk (“volcano mulching”). Excessive mulch on the trunk causes moisture to build up, creating ideal conditions for insect pests, diseases, and decay.
• Ideally, the mulched area around a tree should extend to the drip line of the branches, or at least cover a 4-5 foot diameter area around the trunk. The larger the mulched area, the more beneficial.
• Check the mulch depth annually and replenish as necessary.

BENEFITS OF MULCH

Provides an insulation layer. Mulched soils are warmer in winter and cooler in summer than bare soils. Roots are protected from temperature extremes, creating less freezing and thawing of the soil in winter, which can heave and injure plants.