Mulch and bark

Selection of the correct materials helps to protect plants and can also absorb impact.

Mulching materials come in many different forms, ranging from the dedicated tree mat, via sheet mulching, through to particulate products such as bark, woodchips and green waste. Some particulate products are also suitable for use as loose impact-absorbing surfaces in playgrounds.
For many people, price is the deciding factor when purchasing bark products or other mulching materials. But, as with most purchases, consider the value-for-money aspect. Buying a cheap product may save money but it could cost dearly if it fails to conserve moisture and prevent weeds, or if playground surfaces fail to provide the impact-absorption needed when a toddler tumbles from a slide.
Mulch mats will be appropriate for individual trees and shrubs while sheet mulching is relied on heavily by nurserymen and is also used under particulate mulches in the landscape. The aim is always to eliminate light to prevent weed seed germination and to conserve moisture while letting rainfall or irrigation water through to the soil.
Longevity of product is also important if trees and shrubs are to benefit during the period of establishment. However, consider how the mulch material will be disposed of.
The range of loose mulching products is huge and one of the primary considerations is particle size because it affects the performance, life expectancy and appearance of the mulch.
Site features — particularly gradient, exposure to wind and likely rainfall, as well as the size of the plants and length of time to maturity — will influence product selection. A sloping site by the sea will need a heavier grade material to ensure stability. Large particles may have a longer life before they break down but a balance is needed — if very large particles are used at a less-than-recommended spreading depth, gaps may form that permit light to penetrate to the soil and allow weed germination.
Species is also important. Pine bark mulch tends to be chunky and is very attractive in its appearance. It also smells nice. Spruce bark is a cheaper alternative — it has a flat, leathery appearance but is adequate for many situations. Appearance is a matter of personal choice but the darker-coloured barks are deemed aesthetically more pleasing and tend to be used on more prestigious sites.

Putting it in place
Make sure that the product is easy to handle. Stringy materials are difficult to shovel, whereas mulch of rounder particles is easier to shovel and rake out. Products that are smashed to pieces, full of dust and fines should not be used. Watch for contaminants too — you do not want glass, plastics or chemicals in the product.
One type of product becoming more commonplace is green waste. High transport costs and landfill taxes mean many local authorities, contractors and other high-volume green-waste producers try to re-use botanical waste from their work. Surpluses may be available for sale. Mulch made from green waste has its place in landscaping — but only if properly composted. Composting that takes place on site may rob the soil of nitrogen for the process. Specifiers should also be aware of the possibility of pest and disease transfer, increased fire risk and the likelihood of lightweight material being blown by the wind.
Whatever type of mulch you consider, check the specification and see a sample of the product before ordering.
While not suitable in every situation, bark and wood-based products are useful as a loose impact-absorbing surface in playgrounds. They are environmentally friendly, aesthetically pleasing, readily available and of low capital cost. They are easy to install, simple to extend and can be maintained using a low level of skills. They are difficult to vandalise, free draining and will not easily freeze, so will allow year-round play. And, at the end of their usefulness as a play surface, the products can sometimes find a secondary use as a soil ameliorant or mulch.
When selecting a product for use as a loose impact-absorbing surface, it is worth noting that wood-based material is easier to negotiate with wheelchairs, walking frames and crutches. As with all playground surfacing, the important factors to consider include the age and ability of children using the facility, the site type and characteristics, the play equipment involved and the availability of finance and labour for maintenance.
Always obtain genuine proof of up-to-date product testing along with technical information and a sample of the product before ordering.

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