Pine needles litter the ground in pine groves, forests and home lawns. These pine needles form layers on homes, roadways and under the trees. Because each tree contains tens of thousands of needles, the tree debris accumulates and covers surrounding bushes, plants and structures. The pine needles act as natural mulch, protecting landscape plants from weather and adding nutrients as the needles decompose. Using pine needles as mulch has advantages and drawbacks.
Pine trees are evergreens with needle-shaped leaves. These needles typically mature at 5 to 18 inches long, depending on the pine variety, and fall to the ground. Forest owners rake and bale the fallen pine needles, called pine straw in some regions, and sell the bales for landscape mulch. Home residents hand-rake pine needles from their landscape trees and use the needles as mulch around shrubs and flowers. The dry needles are highly flammable and clog roof gutters, making them a home hazard. For safety concerns, many homeowners annually remove the dry needles from their roofs and transfer them to the landscape.
Pine needles or pine straw make a lightweight, woven organic mat around plants. This mulch insulates plants, allows air circulation to the soil and decomposes slowly. This slow decay is beneficial to perennial flowers, shrubs and trees as it releases nutrients into the soil. The needles interweave into mulch that breaks up rain drops, prevents soil erosion and reduces water evaporation from the soil. This lightweight mat settles quickly, requiring frequent needle replenishment. An inch per year must be reapplied to maintain most landscape pine needle mulches.
Pine straw bales are common and inexpensive around pine forest lands, but in other regions, they are costly due to shipping costs. The pine needle bales are unrolled or flaked apart and the needles are fluffed, by hand or with a pitchfork, during application. In dry or fire-prone areas, these loose pine needles are a fire hazard and should not be used near the home or close to structures. Some cities and regions prohibit pine needle mulch due to its high flammability. Check with your fire marshal before using pine needles or pine straw around home landscaping.
The airy layers of pine needles are perfect hiding cover for invading rodents. Rats and voles use cover of thick mulch to invade home areas. Rake the straw to one side and check for tunnels or droppings when pests are evident. The pine needle mulches are hosts for insects and fungi that can infest plants. People with allergies should use protective gear when applying pine needles as natural pine habitat contains dusts and moulds. These particles cling to the needles and trigger allergic or asthmatic reactions in some people. Rake pine needle mulch off sidewalks and driveways as the material is a hazard for foot traffic. Like any vegetative straw, the stems are round and slippery underfoot.
- University of Missouri Extension; Mulches; Christopher J. Starbuck; June 2008
- North Carolina State University Extension; Mulching Trees and Shrubs; Erv Evans; 2000
- Glacierland Resource Conservation and Development; Pine Straw Feasibility Study; Donald R. Peterson
- Texas AgriLife Extension Service; Pine Straw as a Ground Cover Mulch