Garden bark mulch has many functional uses in the landscape, including helping to suppress weeds, although it doesn’t provide an impenetrable weed barrier. It’s an organic form of mulching, conditioning the soil as it deteriorates. You shouldn’t layer bark mulch too deeply or problems with moisture and disease can put the plants’ health at risk.
Garden Bark Mulch for Landscaping
Bark mulch is used with ornamental shrub planting as a method of weed control. Bark mulch suppresses weeds by blocking light that seeds need to germinate, but it doesn’t completely prevent weeds. It also helps retains moisture in the soil and keeps plant roots cool in hot weather. Bark mulch resists compaction, it doesn’t blow away and it provides an attractive finish to newly planted areas. It’s also a by-product of the lumber industry and so readily available.
Mulch Depth to Prevent Weeds
To determine how much mulch you’ll need for an area, use an online mulch calculator. You’ll need to know the width and length of the project area to determine the square footage of the bed you plan to mulch, along with the depth of mulch you want to apply to the area.
Bark breaks down slowly and will not need replenished often – some of our mulches laid 5 years ago are still as effective today. However, routine top ups may be necessary should soil show through (often as a result of animal interference or cultivation techniques). We’d recommend that you replenish bark every 2-3 years in order to maintain its full benefits. The coarser the bark, the longer it should last.
The exact processes involved are not yet proven, but an anti-biotic effect is suspected to arise from micro-organisms within the bark. Mulching with bark creates a much healthier root environment, which is also thought to be a contributing factor.
To what depth should I lay the mulch?
When used as a soil conditioner, or in tree planting, however, bark will reduce the amount of nutrients available to plants. This is not considered a major concern as when the bark decomposes, the nutrients are re-released into the soil as the bark acts as a slow release fertiliser.
The pH of our bark is on the acid side of neutral, pH5-6. In comparison, peat is usually in the range of pH3-3.5. Because bark lies on the soil surface, it allows for the passage of rainwater and air into the soil, and therefore has no harmful effect on the soil’s pH.
Does bark combat plant disease?
To work out how many bulk bags you need, simply multiply the length, width and depth of your area in metres. For example: 4m (length) x 5m (width) x 0.05m (depth) = 1m3 (1 bulk bag).