Heather N. Kolich, ANR Agent, UGA Extension Forsyth County
Of all the pests that trouble plants, weeds cause the most economic damage. While many gardeners want to get away from chemicals, we seem to be conditioned to battle pests with some sort of spray. So we get lots of calls here at the Extension office from people looking for a spray that will provide natural weed control.
Well, there is no spray, chemical or natural, that controls all weeds under all conditions. But guess what? The hands-down best weed control for gardens and landscapes is all natural mulch.
Mulch creates a physical presence that interferes with seed germination and seedling emergence. Sunlight can’t reach weeds underneath the mulch barrier. Denied the light they need for photosynthesis, weeds weaken and die.
Mulch has the added benefits of maintaining soil moisture and moderating soil temperature. Organic mulches such as pine straw, pine bark, and wood chips restore organic matter to the soil as they decompose, improving soil structure and fertility. Inorganic mulches such as lava rock, crushed gravel, and river rocks don’t decompose, but they may create heat islands that can damage tender plants. The weight of rock mulch may also cause soil compaction.
To get the best results from mulch:
- Apply a 3-4 inch deep blanket of organic mulch around the root zone of plants. This is sufficient depth to shade out weeds, but not deep enough to suffocate roots or tempt rodents to nest in the mulch. Remember that roots extend horizontally through the soil far beyond the plant stem, so just as you dig the planting hole 2-3 times wider than the pot, make your mulch island 2-3 times wider than the spread of the plant’s leaves or branches.
- Pull mulch away from the stem or trunk of plants. One of the functions of mulch is to retain moisture. This is good for roots, but bad for stems. Constant contact with moist mulch – as in mulch volcanoes – can rot stems and bark, leading to plant death.
- Use aged mulch around plants to get more immediate benefits of nitrogen release.
- Use freshly ground tree trimmings on paths and unplanted areas for the best weed control. This green mulch initially reduces soil nitrogen, but as the mulch ages and decomposes, it returns that nitrogen to the soil.
Better yet, you can get free mulch at the Forsyth County Recycling Convenience Center at Coal Mountain Park, located at 3560 Settingdown Road. This mountain of mulch comes from the annual “Bring One for the Chipper” Christmas tree recycling event and county maintenance branch trimming. Bring your shovel and containers for yet another benefit – a free mulch workout!