Weeds are adventitious plants in the wrong place, and gardeners remove them to make space for wanted plants and to keep their growing areas tidy.

All weeds can be composted, but some plants have roots which can grow in cold comost piles, and many weed seeds can survive in an ordinary garden heap and grow when the compost is used in the garden. There are three potential solutions, known as hot, wet and dry.

Hot CompostingEdit

If a large amount of biodegradable material is piled up, and has enough oxygen, moisture and small enough particle size (chopped or shredded), the microbial activity causes the pile to heat up. The warmth increases the rate of decomposition and thus the heap may heat up to a temperature which kills roots and seeds. It is unlikely that a garden heap will reach sufficient temperatures for enough time to achieve this.

DryingEdit

Perennial roots and vegitative material can be dried before composting, and if dried sufficiently, they will be killed and won't re-grow. Roots like Ground Elder, Nettles, Thistles etc can be dried on wire netting or on a concrete surface in dry air, and when crispy, added to the pile. However, this method will not kill seeds, which are adapted to drying.

DrowningEdit

All normal garden weeds are unable to survive immersion in water for weeks on end, and crucially, this includes seeds. If you have a pile of weeds which include seeding material such as docks, dandelions, thistles etc, this can all be submerged in a bucket or barrel of rain water for a few weeks or months. The resulting brew will smell strongly and the liquid will contain lots of nutrients, and can be used in a similar way to nettle tea or comfrey tea. The solids can be tipped onto the compost heap where they will rot down, and drowned seeds won't germinate.

John Cossham 12:52, March 21, 2010 (UTC) Master Composter, York, UK