Did you know that around half of the contents of the average rubbish bin are compostable?
This potential reduction of stress on our landfills and environment is only one of the many benefits of composting. At the final home gardening workshop at Hollard Gardens last Sunday, presenter Sue Rine's first question was: why compost? Answers from the 100-strong crowd included: to recycle; to improve soil structure, water-holding capacity and drainage; to increase nutrients and beneficial organisms; and of course to save money.
There are many different ways to compost. Organic waste will always eventually break down and the speed of the process depends on how much time and energy you want to put into it. Some rules of thumb for successful composting include:
- Maintaining moisture levels (to those of a squeezed-out sponge).
- Allowing the compost to "breathe" (perhaps by putting twigs at the bottom of the pile to let oxygen in and carbon dioxide out, and turning the pile regularly).
- Balancing the carbon-nitrogen ratio (around 30:1).
Carbons are your "browns" - cardboard, newspaper, clippings and prunings and so on. Nitrogen-rich material, or "greens", include your veggie scraps, teabags, coffee grounds and grass clippings. The balance should be maintained because the bugs that break down the carbon-rich materials need nitrogen for energy. Sue says that's why you wouldn't want to just bury pure "browns" directly in your soil - it would become depleted of nitrogen.
One nice tip for material that won't compost easily, or for bad weeds that may still propagate in your compost pile, is to make a separate liquid fertiliser. Use an old drum and cover the waste matter with water - it will break down into a nutrient and microbe-rich compost tea. You can use this directly on your garden as a liquid fertiliser, or sprinkle it back on to your compost - it is full of micro-organisms they will accelerate the decomposition process.
The second question Sue asked of the crowd was: Why companion plant? Companion planting and "guild" design are methods of enhancing your garden or farm system so that the organisms (be it plants, insects or animals) co-operate and assist in the growth of others.
For example, you can attract beneficial insects (often plants from the Umbellifereae family, such as parsley, carrots and celery), repel harmful insects (marigolds and calendula distract, repel and mask your veggies so no-one eats them before you), provide nutrients (leguminous plants such as peas fix nitrogen in the soil, and flax, willows and poplars provide drought food for your animals as well as tannins that are good for killing their parasites), or in some cases simply provide shade and support for other plants.
The home garden that has been developing at Hollards in conjunction with the workshop series will be open for viewing during the Rhododendron and Garden Festival. It boasts veggie beds, espaliered fruit, taties in tyres, composting and worm farms, a mobile chook dome and a beehive.
When it is fully established we hope it will demonstrate how the diversity of a home garden system results in it working for itself - with minimum input of time, energy and money from the gardener and maximum production of healthy, tasty food.