What can — and shouldn’t — go in the compost? So, for example, a lot of people don’t compost dock or couch grass, and various other perennials. But I tend to just throw it all in, for better or worse. Presumably if the heap gets hot enough or is left for long enough, it all rots down.
— Weed Heap
Dear Weed Heap,
Thank you for your question. The deadly couch grass is right up there with cockroaches, rats and nuclear war. Dock I’m not so worried about, but it’s amazing how virile dock root is coming away in a compost heap, so keep it out, along with its seeds. The leaves are great in the heap.
1. Throwing it over the neighbour’s fence. Well nearly, I throw it on to shrubs to dry out and get frazzled.
2. Think free fertiliser. A 20-litre bucket or a bin filled with water and in go all those weeds you don’t want to put in the compost heap. Couch root, dock root, thistles and any other weeds that have gone to "flower" or "seed". Let it rot down then pop some in a watering can, diluted 5:1, and feed your heavy feeders (broccoli, tomatoes ... ).
Generally, most people make what we call "cold" compost heaps. These are heaps that are added to over time. Sometimes it takes many months to fill up. This kind of compost heap is a weed seed-free zone, as there’s no heat to fry the seeds so they can’t germinate.
Other materials to avoid include grass that has been sprayed with herbicides. You’ll need a two or three week stand-down period on any clippings. There really isn’t much else that can’t go in your compost heap. If it’s lived before it can live again.
Consider natural alternatives to encourage diverse soil biology and healthy grass. Compost and biochar mixes, liquid seaweed, E.M. (effective micro-organisms) are some possibilities.
Composting can be slow but with a cover on and a 50/50 mix of carbon-rich (straw, woodchips, shredded cardboard) to nitrogen-rich ingredients (food scraps, grass clippings, manure, weeds) and good moisture levels, we will create awesome compost. Chuck in a handful of ‘‘compost’’ worms if they’re not there already for an even speedier process.
Happy gardening
Dr Compost