Effective Mulching Methods

Mulching is an underrated but extremely beneficial practice an owner can use to sustain or prolong the health of a tree.

What is Mulching?

Mulches are materials that can be put on top of soil to help maintain moisture or improve soil conditions. It is one of the best techniques a home owner can take to improve the health and vigor of a tree. Allotment owners frequently use this technique to help nurture and grown vegetables. However, improper use may actually have a detrimental impact on the plant.

Benefits of Mulching

  • Gives a good visual and well-cared for look to plant beds.

  • Reduces the chances of tree damage from trimmers or lawn mowers.

  • Inhibits some plant diseases.

  • Improves soil fertility as most mulch types will decompose.

  • Provides insulation for soil, protecting shallow roots from extreme summer or winter temperatures.

  • Controls weed and pest growth.

  • Reduces soil moisture loss into the atmosphere.

The ideal conditions for tree growing is a wooded or forest environment. Within this, trees have roots anchored into rich, aerated soil that is full of essential nutrients a tree needs to be healthy. With urban sprawl, more and more trees are becoming exposed to urban environments. This environment is much harsher with poor quality soil, reduced organic matter and large fluctuations in both temperature and moisture. In such cases, by applying 2-4 inches of mulch, we can mimic a more natural environment that a tree craves.

Types of Mulch

You will find many types of mulch on the market. They generally fall into two categories: organic and inorganic.
Organic mulches are the most common form and include things such as wood chip, pine needles, hardwood & softwood bark, cocoa hulls, compost mixes and a variety of other products, usually made from formally living organisms. Organic mulches will decompose over time at different rates, depending on climate and the materials within it. It is preferred by gardeners and tree surgeons because the decomposition qualities are often seen as ones that help soil quality.
Inorganic mulches include things such as stone, rock, rubber, geo-textile fabrics, and other materials. Inorganic mulches do not decompose so do not need to be replaced as regularly, this is why local authorities and councils often use this type of mulch in public spaces. Because of their inability to decompose and improve soil quality, most professionals will opt for organic mulches should they be given the choice.

Little and Often

The benefits of mulching are plentiful. However, applying too much can be harmful. The ISA (International Society of Arboriculture) recommend a depth of 2-4 inches. Be careful not to pile it high and produce a ‘mulch volcano’. Ensure organic mulches are properly decomposed before placing more on top.

Problems with Mulching

  • Some mulch can give off sour, distasteful odours. This organic matter may produce acid upon discomposure which can harm young un-established plants.

  • Thick blankets of mulch can knit together and exhibit the entering of water or air into soil.

  • Mulch piled high against tree trunks can attract rodents that may chew the bark.

  • Some mulch types can seriously affect the pH level within the soil. This may be detrimental to the conditions the tree prefers.

  • Too much mulch against a tree trunk can allow insects and disease to enter the tree trunk.

  • On wet soil, too much mulching can lead to excess moisture, which can stress a plant and cause root rot.


Mulching Method

The type of mulch you use or plan to use will depend on factors personal to your needs. Whichever method you choose, there are some generic guidelines that are best to be followed:
  • Firstly, check soil drainage within existing soil, if soil is poor draining anyway, adding mulch could limit water penetration even further. It’s even possible to check pH levels with the use of a testing kit. Some plants will benefit from acidifying mulch such as pine bark.

  • For well drained locations, 2-4 inches of mulch can be added (less for poorly draining soils). Mulch can be put from near the base of the trunk all the way out to the edge of the trees crown. Remember, trees rooting systems often extend beyond the drip line.

  • If mulch has previously been placed, check the level and composition. Use a rake to break it up if you wish to place more on top. If mulch becomes dry and faded overtime, a water soluble, vegetable based dye can be used to freshen it up.


Mulch should not be piled or stacked against a stem or trunk. If so, pull it back until the base is exposed. Wood chip mixed with leaves and bark generally make the best type of mulch. As a tree services company, we supply local garden centers and allotments with this type of mulch on a frequent basis. If can be purchased cheaply and if used correctly, will improve the health of plants on your site.

Thanks for reading
Sam Clark
Tree Surgeon
SPC Tree Services

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