Marina Bistrin is an avid gardener. In 2017, she gave a presentation on ‘extreme composting’ at Eltham Farmers’ Market. Here are her notes (updated in 2022).
If you have the time and space at your place to compost the contents of your green bin, it’s a great thing to do. You can compost everything, from the easiest to the most difficult weeds, and even logs, in hugel mounds. You can make a nutrient-dense compost, especially if you include the weeds which are nutritionally dense. Many of these weeds are ancestors of our vegetables, but breeding bigger and blander vegetables has diluted the nutritional content of them. Many weeds are part of traditional diets, part of herbal medicine, and some are classed as tonics because they have so much nutrition in them (minerals and more complex compounds).
Composting your green bin contents lessens the work that your Council has to do with picking up green waste that then needs to be transported to sites in the countryside where they are composted and make biogas. The compost that you buy back from these companies often includes a high proportion of woody waste in the mix, which results in a high carbon but less nutritionally dense compost. Finally, dealing with your weeds can be fun and a great children’s activity (I think squashing with rocks is especially enjoyable!).
Why do weeds make such good compost and fertiliser? Weeds have a lot of leafy matter full of minerals. Also many deep-rooted weeds mine minerals from deep in the soil that your veggie plant roots can’t reach and bring them up to the surface via the leaves.
The difficulty with composting weeds and prunings is that some can re-grow in your compost and therefore need to be treated differently. That’s why I invite you to sort your common weeds into your best (easy to compost) and worst (difficult to compost) weeds and decide which you can hold onto to add to your compost and which you feel are better going into your council green waste bin. If you have the time and energy, plus the space on your land, you may want to compost absolutely everything, or at least try it once as an experiment. The easy to compost weeds can often just be dropped onto your garden and left there to break down, without risk of re-growing. It looks a bit messy, but that’s your choice to make. They become a sort of mulch.
I have been mostly composting in plastic cylindrical compost bins with lids, which keep the moisture and heat in but don’t produce the high temperatures necessary to kill seeds and pathogens and grasses like kikuyu / couch. I have also been making compost paths within the garden, but I don’t include food waste in these; rather I use prunings, grass clippings, wood chips, sawdust, coffee grounds, etc. I have also made compost on concrete paths surrounding the house to cool the house too. That creates an insulating layer to stop the concrete getting too hot. If you wanted to, you could grow a ground cover on this to cool the house even further.
Here are the methods I have used to deal with weeds before composting. You may want to use a combination of methods for different parts of the plants e.g. treating leaves and roots separately.
Methods of killing plants
- Tearing the roots off.
- Crushing roots with fingers or a rock.
- Cutting into small sections.
- Drowning for a month or two till they are mushy (and stinky).
- Steaming (solarising) by leaving in a plastic bag on hot footpath for days or weeks.
- Hot composting.
Problematic plant parts – treatments before adding to your compost
It’s useful to think of the plant according to its different parts as some are much easier to compost than others.
- Soft bodied and rooted plants – cleavers, chickweed, petty spurge, grasses without runners. Often ripping the roots off is enough and they compost easily.
- Runner roots and tough stemmed creepers: a few of my worst weeds are the invasive grasses with runners such as kikuyu and couch. These thick runner stems or roots grow underground, and have a store of starch or energy in each root segment, so they are resilient and will stay alive for a long time. Unfortunately, they can re-grow from small sections of root. I usually drown these for a month or two, and will often pour this goo into a compost, which quickly absorbs the smell. You can also dilute this and use it as a liquid fertiliser.
Tradescantia will grow from small sections of stem too, but has soft tissues which you can crush easily (if you are really feeling like a work out!). Another plant I have difficulty with is ivy – they have strong stems and roots, and will regrow from small sections too. Creepers such as honeysuckle are almost as difficult to deal with as they spread by layering – the tough stems that touch the ground can send down roots.
- Bulbs/corms – oxalis, agapanthus, watsonia, onion weed. These can all be crushed with a rock, drowned or solarised/steamed.
- Deep taproots – dock, comfrey, dandelion. These tend to send up leaves again and again from any roots sections left in the ground. They bring lots of minerals up the surface via their leaves, which can be a good thing. I usually crush these roots.
- Fibrous, tough roots – ivy roots, honeysuckle, shrub roots. Can be cut into small sections – solarise or drown.
- Seeds – grasses (ripe seedheads), other seedheads and fruit. Heating is the most effective method of killing them. Best to weed before seed set takes place.
- Cuttings/prunings – shrub prunings such as hydrangea, mirror plant, camellia, privet and roses may grow from cuttings thrown onto a compost path, but will generally compost successfully in an enclosed bin. Other plants that grow from cuttings include ivy, succulents, geraniums, purslane. The smaller the pieces, the less likely they will grow, so I will often put these through a mulcher or drown them.
- Insect damage or disease – regarding citrus gall wasp in prunings, I suggest boiling for a minute as it kills the larvae quickly. Drowning will work too. You can just cut out the gall sections and deal with them separately so you are not working with huge volumes of prunings. Boiling or microwaving should inactivate most resident insect pests and diseases of plants, though personally I tend to put any plants with fungal disease in my green waste bin.
- Thorns – composting these is hard work. Thorny prunings such as roses and bougainvillea will usually be discard in my green waste council bin. They are dangerous as the thorns last a long time in compost and may give you a nasty infection if they haven’t decomposed and you may need a tetanus shot pronto! I like to use my hands to spread compost around so am not going to take any risks with thorns. If you are really keen, you can chop the very tips off the thorns and that will make it safe to compost. Seeds such as peaches and nectarines also have pointy ends – you can rub the ends of them onto concrete paths or crush the ends until the tips break off.
- Logs and branches. Usually branches don’t re-grow and can be used for composting, dug into the ground (Hugel mounds) or for edging. Hugel mounds absorb and hold a lot of moisture for years, and they encourage fungal growth which helps other plants grow. These mounds can also help to create moist microclimates or havens which protect your plants from wind and drying out and add interest to the landscape. They also can be piled up and planted over, so that you get more surface area to grow on. Even dry branches are useful as windbreaks and shade and cool the soil in the summer heat, and you can grow crops up them such as beans. They can also shelter lizards and other creatures in your little ecosystem. If you are lucky enought to have a blue-tongued lizard, they like to eat snails and slugs.
A trailer for Farming With Nature: permaculture, including Hugelkultur, on a mountainside in Austria with Sepp Holzer – an interesting synopsis of his methods with beautiful visuals of his farm.
Nillumbik Council allow food and meat scraps in their bins, wrapped in newspaper – they go to the Veolia facility.