Composting weeds is not as simple as composting other organic materials.
Many gardeners spend much of their time pulling weeds out of their garden and prefer to not take any risks of reintroducing weed seeds into their gardens through compost, however, others like to compost as much as they can ‘in house’.
Not all weeds are equal and some are safer for your garden compost than others, but rather than looking at each weed individually, it’s easier to follow a few basic rules of composting weeds.
Ideally all weeds should be picked before they reach maturity and the seed bearing stage. It’s when they mature and start producing seeds that they can become most detrimental to the compost.
Compost should produce temperatures around 55 to 60 degrees celsius. This number isn’t as important if you are not attempting to compost weeds, but if you are putting weeds in your compost you will want to pay close attention to temperatures.
High temperatures can destroy weed seeds and create a clean compost, but remember some weeds are hardier than others. A soil thermometer can be stuck into the compost heap to monitor temperatures. You need to generate enough heat for the microorganisms to break down the weed material.
Some gardeners prefer to set up a seperate compost pile specifically for weeds. This gives you confidence in your compost material that consists of vegetable peels and grass clippings and allows you to monitor the quality of the soil created from weed compost.
The weed compost can be left for a longer period to help in breaking down the material and can be tested to see if weed seedlings sprout up from the created compost soil. You can take samples of the soil and put them in small pots, add some water and watch for signs of growth. If you don’t see any weeds sprout up you can have confidence in adding that soil to your garden.