Stop Food Waste Week

Composting Garden Materials

Composting garden materials is easy if you keep the following four basic essentials in mind:

  1. Balance of green and brown materials
  2. Size of materials
  3. Adequate moisture
  4. Sufficient aeration

The composting organisms require a balanced diet of green and brown materials. Luckily most garden materials are well balanced such as hedge trimmings, old veg and flower plants, cut flowers and weeds, and can be easily composted on their own without the addition of other materials. The challenge is when you want to compost food or grass clippings because these are wet and high in nitrogen and therefore need balancing with drier brown materials to optimise the composting process. Try a mix of half leaves and half grass clippings (leaves can be collected in the autumn for mixing with spring and summer grass clippings). Food can be mixed with leaves or shredded paper or cardboard. 

Composting happens from the surface inward so the smaller the materials are, the faster they will break down. You can chop materials with a spade, cut them up as you are gardening with pruning shears, run over leaves or weeds with a lawn mower, or put woody trimmings through a shredder. The smaller particles will allow you to mix materials more thoroughly when making the pile and also makes it easier to turn the pile to promote aeration.

Adequate moisture is critical as the composting organisms live in the film of moisture that surrounds each particle. Without this, composting does not happen or will happen very slowly. However, too much moisture can drown or suffocate the pile where it can become slimy and smelly. Ideally materials should be moist to the touch, like a wrung out sponge, but not soaking wet. We recommend that you mix and wet fresh materials on the ground outside of your composter before adding them to the pile. This way, excess water can drain into the soil rather than into your partially composted materials.

The organisms that work best in your pile thrive in the presence of oxygen. In a pile with a good mix of materials, oxygen will penetrate from the surface inward or in a hot pile from the bottom up as heat rises. To promote aeration and speed up the composting process, place coarser materials on the bottom, add rigid materials such as twigs or leaves to the initial mix of materials, turn the pile, or periodically mix materials using a pitch for or a cork screw type aeration tool.

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