Mulch - why compost is good for mulch

This specification applies to the mulching of various types of plant materials, including trees, shrubs, herbaceous plants and bulbs.

How to use:

Uniformly apply compost mulch over the entire treatment area, or in a one metre circle around the plant. Apply the compost mulch at a 25 - 75 mm layer over the area to be treated (2.5 – 7.5 m3 per 100 m2), or in a one metre circle around a singular plant (20 – 60 litres per tree). Apply mulch as soon as possible after planting, applying it closely around plant stems but not against them. Water plant(s) in thoroughly prior to mulching, then again after mulching.

The addition of a compost mulch will reduce the required frequency of watering. In many cases, applying a compost mulch may reduce post planting fertilisation, as the compost mulch will supply some soluble nutrients (when a stable compost is applied at recommended rates).

Compost specification for use in mulching:
The mulch specification outlines further requirements, in addition to BSI PAS 100, for the use of quality compost in mulching:

pH units (1:5 water extract) of between 6.0 – 9.0
Electrical conductivity (1:5 water extract) of 3000 µS/cm / 300 mS/m (max)
Moisture content  of between 35 – 55 % m/m of fresh weight
Organic matter content of more than 30% of dry weight
Particle sizing of air-dried sample passing the selected mesh aperture size - 99% pass through 75mm screen
<25 pass through 10mm screen