How to Compost your weeds

None of your bushcare weeds need to go to landfill – they can all be composted, including seeds & tubers. The exception is corms (Montbretia and Watsonia) which we will cover soon.

This hot composting method will enable you to compost down all the weeds from your bushcare site in about three months to use on your veggie garden. It is a method that is best done in a   garden rather than bushcare sites because of the concentration of   nutrients which leach into the soil. Nothing needs to be purchased except maybe the steel mesh when you first set up.

Here are the steps:

  1. SELECT A LOCATION  choose somewhere that will benefit from the nutrients that will leach into the ground; eg under a fruit tree, upslope of your vegie garden, NOT near bushland or a creek. It is useful to have at least 2 going at once.
  2. CONSTRUCT A FRAME The minimum size of compost needed to generate sufficient heat is 1 cubic metre; ie 1 m x 1 m x 1 m high. The larger it is the better. Steel mesh with 50mm X 50 mm squares is an ideal material and comes in sheets of 2000 x 1200. Cut 2 sheets into 1/2s giving 4 panels of 1m X 1.2m. Then wire 3 sides together using tie wire, leaving the front one open for now. This will allow you to start filling the bin easily without straining your back.
  3. BASE LAYER Lay down a layer of sticks or loose material that will provide aeration.
  4. PROP A BARRIER IN FRONT OF THE BIN  about 500 mm high to keep the contents in place. This temporary low ‘front door’ will allow for ease of piling till it is about ½ full. Some props will be needed to hold it in place – bricks, rocks or full kitchen scraps buckets.
  5. BROWN LAYER – CARBON Add a layer of dried vegetation about 250mm thick.   This can be – dried weeds, and also shredded paper, dried leaves or wood shavings. To dry out weeds from site they will need to be stored off the ground and in containers/bags that don’t trap the moisture.
  6.  GREEN LAYER – NITROGENAdd a layer of green material about 150mm thick – fresh weeds and vegetable scraps. These will be the weeds mostly recently collected which are still green, such as weed grasses. Green kitchen waste needs to be stored carefully to ensure it doesn’t attract animals. Do not include meat or fats in this.
  7. ACCELERANT LAYER Add a layer of accelerant materials about 50mm thick – chook manure, grass clippings, comfrey, yarrow, urine, dolomite, seaweed.
  8.  WATER After each accelerant layer, add water in any of the following ways (or just water is also fine)Weed tea – made by soaking weeds in water for at least a few days, but longer is better; Comfrey tea – same as weed tea, except more potent, particularly if soaking for weeks; Seaweed mix;
  9. REPEAT steps 5, 6, 7 & 8 until the bin is about ½ – 2/3 full
  10. WIRE FRONT ‘DOOR’ ON When bin is about ½ full wire on the front panel and remove the temporary barrier
  11. ADD A LID Continue to repeat steps 5, 6, 7 & 8 until the bin is full – finish with the carbon layer. It is best to overfill it as the contents will pack down within a day or two.   It is useful to have something to stop the top layer from blowing away and to let the rain in. This is only needed for a short time. Old cotton clothes, coir mats, old carpet or shade cloth can work.
  12. WRAP IT UP Whilst your bin needs good air flow, it works best if the heat can also be retained. Shade cloth or sediment control fabric works well to cut down the cooling effect of breezes. Alternatively you may locate the bin where it is protected from winds by shrubs, a fence or some other semi-solid barrier.
  13.  HANG OUT THE WEED BAGS & CLEAN UP It is important to hang out the weed bags to dry for about a week, then store for reuse.   Allow time to clean out and dry kitchen scraps buckets. Next is you – you will be a bit smelly too! The bin may be a bit smelly for about a day but it soon goes.
  14.  USE COMPOST ON YOUR OWN GARDEN  You do not need to do anything more for about 3 months – no turning to aerate the bin etc.After about 3 months it should be ready, except there will be some materials at the edges that need to be put aside to go in the next bin. Take off the front panel, so it is easy to get at. You can then keep the bin in this location or move it – it is easy enough to move with the 3 panels connected. When you have collected enough material you can start again