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MULCH FACTS
A mulch layer around trees, shrubs, planted beds and covering bare ground provides many benefits. In areas that are difficult to mow, irrigate or otherwise maintain, use mulch to replace turf or groundcovers. Also consider placing mulch in shady areas where plants don’t grow well.
- Organic mulch materials improve soil fertility as they decompose. Organic mulches include bark materials, pine needles, compost, and paper.
- Over time, many types of mulch improve soil aeration, structure and drainage.
- Mulch buffers soil temperature, keeping soils warmer in winter and cooler in summer.
- Mulch helps maintain soil moisture by reducing evaporation. A layer of mulch also minimizes water needs for established plants.
- Fresh mulch inhibits weed germination and growth.
- A mulch layer can inhibit certain plant diseases.
- Mulch around trees and shrubs (not against the trunk) eases maintenance and reduces the likelihood of damage from string trimmers.
- Mulch gives planting beds a neat and uniform appearance, adding a contrast of color and texture that complements plantings.
- Fine-textured mulches that mat together decrease erosion.
GUIDELINES FOR USING MULCH
Follow these tips when adding mulch to your landscape:
- For well-drained sites, apply a 2–3 inch layer (after settling) of mulch around trees, shrubs and bedding plants. Coarse materials, such as pine nuggets, may be applied to a depth of 4", but don’t allow mulch to accumulate to a greater depth. Do not add mulch if there is a sufficient layer already in place (2"-3").
- “Volcano mulching,” or mulch applied too deeply, hinders oxygen exchange to roots, which stresses the plant and causes root rot. Do not place mulch against the trunk.
- Avoid more than one inch of mulch on a newly planted rootball or shrubs. Too much can cause drought stress to new plants because the mulch intercepts water meant for the roots.
- If mulch is piled against the trunk, pull it back several inches to uncover the base of the trunk and the root flare. Mulch piled against tree trunks and shrub stems holds moisture. Stems and trunks that remain constantly wet are prone to crown rot. Mulch piled high against the trunks/stems of young trees and shrubs may also create habitats for rodents that chew the bark. This can girdle and kill the plant.
- Mulch out to a tree’s drip line or beyond, at least an 8-foot diameter around the tree. Remember that in a forest environment, a tree’s entire root system (which extends well beyond the drip line) would be mulched.
- Create self-mulching areas under trees where leaves can stay where they fall. Fallen leaves are a site resource, not yard waste.
- Avoid thick blankets of mulch and prevent matting. Matted mulch prevents water and air from seeping through. Rake old mulch to break up any matted layers and to refresh the appearance.
- Organic mulches may require weeding and replenishment once or twice a year to maintain a total depth of 2"–3".
- Do not use cypress mulch. There are no regulations to manage wild harvesting which depletes our necessary wetlands.
- Shell, crushed stone, or pebbles can be used as mulch but they won’t contribute to the soil’s nutrient and organic content or water-holding capacity. Limestone and shell both raise soil pH. These materials also reflect heat. While some Mediterranean plants, like lavender, may enjoy this, the excess temperature can stress other plants and increase their water needs.
HOW MUCH TO BUY
Mulch is often sold in bags, by the yard, or by the “truckload.” So, how much mulch do you need for your yard if you want to achieve the recommended depth of three inches?
By the BAG: 1 bag containing 2 cubic feet covers 8 square feet (2 ft. X 4 ft.)USING YARD WASTE AS MULCHBy the BALE: 1 bale of pine straw covers 18 to 20 square feet.
By the YARD: 1 cubic yard covers 108 square feet (9 ft. x 12 ft.)
By the TRUCKLOAD: 1 mini pickup holds 1.5 yards and covers 162 square feet (9 ft. x 18 ft.)
1 full-sized pickup holds 2.5 yards and covers 270 square feet (9 ft. x 30 ft.)
When purchasing 2 cubic feet of mulch
you will need the following amounts to achieve desired thicknessYOUR PLANT BED DEPTH OF MULCH IN SQUARE FEET 2 inches 3 inches 4 inches 25 sq. ft. 2 bags 3 bags 4 bags 50 sq. ft. 4 bags 6 bags 9 bags 100 sq. ft. 9 bags 13 bags 17 bags
Search locally for sources of recycled organic materials. Sometimes you can even acquire mulch for free!Tips on Obtaining Recycled Products for Mulching:
- Use mulch that originates in your own landscape, such as leaves, pine needles, or grass and shrub clippings. Chipping or shredding of fallen leaves prevents matting.
- Local power companies, municipal solid waste departments, and tree services may supply free or low-cost mulch and may sometimes deliver bulk quantities. Try to get only mulch from branch trimming. It is generally more disease-free than mulch from other sources, such as roots.
- Team up with other homeowners and have bulk quantities delivered to your neighborhood.
- If you need lots of mulch for a new landscape, place an ad in the local newspaper so suppliers come to you.
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