6. Mulching

Mulching is a very important part in the establishment of a newly planted tree. Mulch helps maintain soil moisture, acts as a buffer to soil temperature extremes, controls weeds and replenishes organic matter and nutrients in the soil. The mulched area around a new tree should be a minimum of 1.5m in diameter, but 2m to 2.5 would be ideal. The mulch should be 5-10cm deep after settling. The mulch used should be anything organic that is well-composted, for example wood chips that contain a blend of leaves, bark and wood. Pea straw and sugar cane mulch are also very good (Figure 7).

figure7 wFigure 7. Mulch using good organic mulch.
Mulch should be applied so that it is not piled up against the trunk and the root crown is exposed.

Under no circumstances use grass clippings or any material that is still composting and giving off heat.

Grass and tree roots do not mix they can be one of the biggest inhibitors of root development.

Mt William Advanced Tree Nursery also advises against plating bulbs and shrubs under trees and in particular under establishing trees. Most of the fine, absorbing roots are located within centimeters of the soil surface. These roots, which are essential for taking up water and minerals, require oxygen to survive. A thin layer of mulch, applied as wide as possible, can improve the soil structure, oxygen levels, temperature and moisture availability where these roots grow.