If you adopt the preferred method of composting described later (seepages 72-75), which depends very much on worm activity, most of your compost pile will have passed through one or more worms before you use it. Some seeds pass through worms unscathed, but many do not.
Roots or rhizomes of perennial weeds, such as dandelions, docks, and couch grass, are another problem. As far as they are concerned, a compost pile closely resembles their usual, underground habitat, so they are not damaged at all by a cool compost pile. The secret here is to kill them before they go on the pile.
There's more than one way of killing a perennial weed, but I think the best is to lay them somewhere dry and sunny until they are thoroughly shriveled. A more satisfying solution, if you don't have very many weeds, is to smash them thoroughly with a hammer first. Other messier or slower solutions are to drown them in a bucket of water for six weeks or asphyxiate them in a sealed garbage bag for a year.
Bake to death perennial weeds before throwing them on your compost pile.
Some types of garden waste require caution. One of the undoubted virtues of "hot" composting is that weed seeds and pathogens are killed. But traditional, hot composting is hard to achieve in the average garden, so what do we do with such problematic ingredients? Fungal and bacterial pathogens are the worst, but we do need to keep a sense of perspective.
Pests and diseases that live on leaves and stems don't enjoy life in the compost pile, so you don't need to lose much sleep over them. Mildew and black spot are unlikely to survive a long spell in the average compost pile. On the other hand, most soil pests are quite at home in the pile, and are all too likely to survive and be spread around the garden, as are overwintering diseases. There really is no alternative to keeping material with these problems out of the compost pile.
Not very satisfactory solutions are to burn them or bury them in an unused corner of the garden. It's better to add them to a habitat pile, a heap of miscellaneous woody waste intended primarily to provide a wildlife habitat.
When looking at the examples listed opposite, bear in mind that they are for guidance only: no list could possibly be complete, and most available advice on what can be safely composted is anecdotal and contradictory. Also, the longer a pile is left, the smaller the chance that anything horrible will survive. And last but not least, beneficial microbes in mature garden compost are quite effective at controlling many common diseases. But,
Was this article helpful?