Mulch and bark materials

Any old mulch will not do. It's essential to choose the right product for the specific job.

There is so much to choose from — dedicated tree mats, sheet products and particulate materials such as bark, woodchips and green waste. Some are also suited to creating surfaces for walkways and tracks, while bark offers additional properties making it a suitable impact-absorbing surface in play areas.
When selecting a product for mulching or surfacing purposes, many specifiers simply look at the price. But opting for the cheapest may save money only in the very short term. There are many other factors that should be taken into account, including value for money.
If a mulch product fails to conserve moisture and prevent weed development, or if a playground surface fails to cushion a toddler falling from a slide, the cost in the long run could be very high. Such materials should be chosen with care and only after consideration, investigation and examination.
Mulch mats are suitable for use around individual trees in new planting schemes. Sheet mulching is used by nurserymen and also as an “underlay” for particulate mulches in landscape projects. In both cases it is essential that the mulch products eliminate light so weed seeds cannot germinate. At the same time, moisture in the soil should be conserved, although rainfall and irrigation water needs to pass through.

Product longevity must also be considered. Mulch products should provide a benefit to new plantings during the period of establishment. Particulate products with a short lifespan may require “topping up”, while disposal may be an issue with long-life mats and sheets.
Particulate materials, such as bark and woodchips, are popular in landscape schemes because of their pleasant, natural appearance. But with loose products it is essential that specifiers understand particle size and how it affects the performance, life expectancy and appearance of the mulch. The size and development of the plants, site features such as gradient, and factors such as exposure to wind and likely rainfall will all influence product selection.
Sloping sites, and especially those that are open to the elements, will need a heavier-grade material to ensure the particles remain in place. Larger particles may also have the advantage of a longer life before they break down but if used at a less-than-satisfactory depth, gaps between the particles permit light to penetrate the soil and promote the germination of weed seeds.
On some sites, such as roadside plantings and roundabouts, where cigarette ends may be discarded by drivers, it is important to look at the fire-retardation properties of the mulch options.
Appearance will also depend on the site and the nature of the project. Obviously, prestigious landscape schemes need attractive-looking mulches to prevent them from looking shabby.
The importance of appearance and longevity were recently highlighted in research undertaken by Westland Horticulture of Dungannon, Northern Ireland.
“Our research into consumer attitudes and product use showed that gardeners want a mulch that will look attractive and benefit their gardens for more than one season,” reports Westland head of marketing Gillian McLean. “So we have focused on producing a top-quality mulch, using only the finest ingredients, that will enhance the look of any garden season after season.”
The resulting Westland Mini Pine Bark Nuggets, although mainly aimed at the retail market, are aesthetically different from others on the market and are guaranteed to last three to four years.
Specifiers should be aware of the role species plays in the properties of bark mulch. Pine bark, for example, tends to be chunky and attractive. It also smells nice. Spruce bark, on the other hand, is cheaper, flatter and more leathery in appearance. Darker-coloured barks are generally thought to be more aesthetically pleasing.
From the landscaping point of view, two other factors remain crucial when sourcing particulate mulches. Clearly you will want the product delivered when you need it, but it also needs to be consistent and easy to handle. Stringy material is difficult to shovel. Rounder particles are easier to spread and rake out. The mulch should not be smashed to pieces and should never be used if it is found to contain quantities of dust, fines or contaminants such as glass, plastics or chemicals.
These days, there are also large volumes of green-waste mulch material. Such products certainly have a place in landscaping but need to be well composted. Green-waste materials that are still undergoing decomposition will compost further on site and there is concern that this process may rob the underlying soil of nitrogen. Specifiers should also be aware of the possibilities of pest and disease transfer, increased fire risks and the likelihood of the material being blown away by the wind.
Finally, the key to success lies in your judging the product. Whatever type of mulch or surfacing material you consider, always ask to see a sample of the product before placing an order and always obtain genuine proof of up-to-date testing along with technical information. Then, when the product is delivered, compare it with both the specification and the original sample before accepting delivery.

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