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In many Australian gardens lurks a forgotten compost heap or bin that is begging to be rediscovered and revitalised. There are all sorts of reasons why it may have fallen off the radar, so let’s have a look at how to get things back on the rails if you are in that particular heap!

Your neglected compost heap has erupted into a volcano of weeds.
There are some weed species that are very difficult to compost because they are exceptionally hard to kill, things that form bulbs such as oxalis and onion grass, or tough runners such as couch or kikuyu grass. Whilst it is possible to kill weeds through the heat of composting, most home compost heaps do not get to the sort of temperatures required or hold them for the length of time needed either.
 
What to do?

Option 1:
If you are going to kill weeds by composting you need to create a hot compost heap. You will need at least a cubic metre of raw organic material and it needs to have the right balance of nutrients of about 3:1 ‘Browns’:’Greens’ (with ‘browns’ being high carbon materials such as dead leaves, shredded paper and cardboard, sawdust, woodchips etc, and ‘greens’ being high nutrient materials such as kitchen scraps, fresh lawn clippings and green leaves etc from the garden).
 
Make alternating layers of the browns and greens un the 3:1 ratio in a pile. Within a few days it should be too hot inside the heap to leave your hand in it. Every week turn the pile so that everything on the outside goes to the inside to heat up. After a month to 6 weeks any green weeds should have completely decomposed and be unrecognisable.
 
Option 2:
If your local council has a green waste bin, put your worst weeds in there so that they can go to an industrial scale composting facility that will hot compost them to death.
 
Smelly compost
Your compost project may have been abandoned because it started to smell like rotten egg gas or similar. This happens when things get too wet in the compost which encourages the wrong sort of microbes to proliferate. When oxygen levels get very low the conditions are described as anaerobic and results in gases such as methane and hydrogen sulphide being produced which are nasty greenhouse gases as well as being toxic if added to your soil.
 
What to do?
Eventually your smelly, slimy compost heap will settle down once most of the nutrients have been used. Even if it is still a bit stinky the way forward is to aerate it and mix through some ‘browns’ (the carbon-rich material mentioned above).  Getting the balance of ingredients right is a vital part of composting whatever system you are using. A garden fork is a great tool to do the turning as it is generally much easier to use for this task compared to a spade or shovel.
 
The compost did not get hot
A hot steamy compost heap is a delightful thing, but it can be very hard to achieve the conditions necessary to make that happen. The advantages are very worthwhile as it is possible to get the interior of a heap up over 70 degrees Celsius, enough to kill many perennial weeds that can resprout in a cold compost heap. A volume of at least a cubic metre plus adequate moisture and air are some of the prerequisites for a successful hot compost pile.
 
Turning the pile every week or so helps greatly with aeration and to encourage the thermophilic microbes that live and work at such high temperatures. The Tumbleweed Compost Mate is the perfect tool for aerating compost heaps, and operates like a big ‘compost corkscrew’. Apart from hot composting, it is important to know that there are plenty of other species of microbes that are very effective at composting at lower temperatures, a process we call cold composting, which for most households is a very practical and easily managed solution.
 
What to do?
Hot composting is essential if you are trying to compost the persistent perennial weeds mentioned earlier, or diseased plant material. If you cannot meet the conditions for a hot compost heap then it is much better to put those difficult materials into the green waste bin and adopt the cold composting method. The Tumbleweed range of compost bins can all be adapted to cold composting. Basically, you can keep adding small amounts of things like lawn clippings and kitchen scraps as they become available around the house and garden. Gradually these materials compost and as you add new layers on top the process continues such that there is always some finished, mature compost at the bottom of the heap/bin. You can use the Compost Mate to speed the process, but also to take cores of the mature compost from the bottom to use in the garden or as potting mix.

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