| Garden Column for the Salisbury Post Darrell Blackwelder October 6, 2005 Sunday morning after church, I stopped by the grocery to pick up a few items for lunch. It never fails that I have a people ask me gardening questions when I'm about, but never had the exact question asked by two different people. "What is the best type of mulch to use for azaleas?" asked from a lady on the cosmetics aisle and from a gentleman gleaning through the apples in the section. So- here is the long version of my answer. Pine needles, bark nuggets, composted ground limbs, twigs and wood shavings are popular organic mulching materials that I would recommend as mulch for azaleas or other plant materials. Avoid mulching material containing green wood or cellulose such as fresh ground limbs, sawdust, twigs because it will attract termites. Pine needles, bark nuggets and composted material do not have viable cellulose that attracts termites. Even thought we've received the bit of rain earlier this week, adding mulch conserves moisture and reduces water consumption. Organic mulches also enrich the soil and in many instances prevent lawn mower and trimmer damage. Mulches also reduce weed competition and often prevent some weed seed from germinating. But, mulches will not prevent or delay weed growth forever. Mulches should be applied 3 to 4 inches deep over clean, weed free soil. Over mulching can cause serious problems with root development. Heavy applications of fine mulch such as sawdust and finely ground bark inhibits oxygen uptake of trees and shrubs. Grass clippings as mulch may create a "thatched roof effect" prohibiting water penetration. These materials and any other "green" material should be composted before using as a mulching material. Landscape fabric or geo-textile material placed under mulch retards and prevents germination of some weed species. However, this material will not prevent growth of bermuda grass. Bermuda grass, nutsedge and other perennial weeds or grasses must be eliminated before applying geo-textile material. Never use black plastic as mulch. Black plastic either allows too little water or excessive amounts of moisture to accumulate in or around the root system. There is practically no oxygen penetration for root growth which is extremely important to root growth and development.Trees and shrubs often do poorly when black plastic is used under a layer of mulch. Many weeds such as bermuda grass easily penetrates plastic creating a nightmare to maintain. Other materials such as crushed brick, gravel, lava rock, or pebbles can be successfully used as mulching material if the sure the materials are compatible with the design. These materials are often used in commercial situations to reduce fire hazards from smokers. However, many landscapes are not compatible with use of these materials. Inorganic materials in many landscape situations require ground cloth or some geo-textile material to prevent red mud or other soil types from staining the material. Darrell Blackwelder is an agricultural agent in charge of horticulture with the North Carolina Cooperative Extension Service in Rowan County. For archived garden columns or other information, visit the Rowan County Master Gardener web site at www.rowanmastergardener.com , e-mail Darrell_Blackwelder@ncsu.edu |