Life with a Green Johanna

The Great Green Team

20 January 2022

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Composters

/ Green Johanna

Knowledge of the damage that food waste does to the environment has led to a sea change in most people’s behaviour over the past few years.

In addressing kitchen waste, the first change is obviously to minimise the amount of food waste we create because of the environmental cost involved in the production and transporting of food before we even buy it.

But when it comes to dealing with unavoidable food waste, composting is a no-brainer.

The Green Johanna is designed to help you establish fuss-free composting, even if you’re a beginner. It has been a recommended Star Buy in Gardeners’ World magazine in 2021/22/23, commended on the grounds that it accepts all types of food and garden waste, doesn’t need pre-mixing, has a large capacity and is made from recycled plastic.

A Swedish success

The Johanna was designed and originally manufactured in Sweden, which was far ahead of other countries in spotting the need to change attitudes to waste management. It is now made for Great Green Systems in Droitwich, Worcestershire.

There are a few things you need to understand if you want to be a happy composter but once you know, you know. The laws of nature aren’t going to change. You learn this stuff once.

Full instructions are included in the user manual, but here are a few points to remember:

The Johanna needs to be sited on a flat patch of soil or grass. When choosing a location, think about how easy it will be to get to, especially in bad weather. If there is a rodent problem locally, try to choose a spot away from fence lines, logpiles and bushes.

Essential ingredients for composting include air, heat and moisture.

AIR – The micro-organisms that live in the compost need oxygen. Without it, the compost will smell bad and the process will be delayed or stop altogether. So, ensure that you add waste materials loosely and give the top layer a stir with the aerator stick each time. Also, once a month, give a stir deeper down into the compost so that oxygen is always available.

HEAT – As the micro-organisms break down the waste, they generate heat. As the temperature in the compost fluctuates, the types of micro-organisms present also change. This diversity is important to achieve successful composting.

MOISTURE – Composting can’t begin in the absence of water, so it’s important to make sure that the waste materials in the composter contain some moisture. The compost should be as damp as a squeezed bath sponge. If you take a big handful of compost and squeeze it, only a couple of drops of liquid should come out. A balance in the amount of dry and wet materials added will create the right consistency. If in doubt try the ‘squeeze test’ and add different materials as required.

Design features

The Johanna’s design promotes the good ventilation and airflow necessary for happy hot composting.

Vents leading in from the base plate allow air to flow upwards into the container. The round shape ensures there are no cold corners so heat is spread evenly through the compost. The tapered design means that compost sinks towards the centre of the unit and not to its sides, allowing air to circulate and oxygenate the compost.

Lid ventilation system

The Johanna’s lid regulates the ventilation system by covering or uncovering the ventilation holes to adjust air circulation and temperature. It can be set to minimum in cold weather to maintain a warmer compost.

What does the Johanna digest?

The Johanna accepts cooked food waste, including meat and fish, fruit and vegetable scraps and peelings (including citrus peel), dairy, bread, cereals, pasta, rice, crushed or ground eggshells, coffee grounds and filters, tea leaves, tea bags.

The only food-related materials that are not efficiently digested by the Johanna are those that require a very long time to break down, namely large amounts of cooking oil/fat, the hard shells of nuts and seafood (such as oysters and crabs) and avocado stones.

Any bones that are added to the Johanna will be only partially broken down. Stripped-down bones will be present in the Johanna’s finished compost. These are easily removed. However, if you have dogs and feel this would be a problem, we recommend that you do not add bones to the Green Johanna.

Food waste can be added directly or in compostable or biodegradable bags, never plastic. If you tie the bags, once you have added them to the Johanna break them open using the aerator stick to allow oxygen to reach the waste.

From the garden you can add: garden trimmings, grass clippings, leaves, twigs, branches, weeds, bark, wilted flowers. Twigs and branches should be chopped or shredded to provide more surface area for micro-organisms to work on and so speed up the composting process.

How to add and aerate your waste

Each time you add new waste, mix the top layer of compost using the aerator stick, which comes provided. This helps the micro-organisms to do their job properly and speeds up the composting process. About once a month, aerate the whole pile more thoroughly by moving the stick up and down in the compost to prevent it compacting.

Cover each addition of food waste with a layer of garden waste and/or paper and cardboard waste. Garden waste helps to maintain air gaps in the waste material. If you have the space, you could save summer and autumn garden waste for when you need it during the winter months.

Composting depends on a good mix of waste materials that are high in carbon and nitrogen.

 Carbon-rich substances include woody garden waste, wood chips, sawdust, and paper products, such as cardboard and newspaper. Your food waste provides nitrogen, as do fresh grass clippings and fresh green leaves.

Can I compost without garden waste?

If you lack garden waste, you can use the other sources of carbon mentioned. Cardboard should be torn up (with labels and stickers removed), paper and newspaper should be shredded or scrunched up. Toilet roll/kitchen roll tubes and egg carton bases can be left whole in order to create air pockets. Wood chips are useful as they hold structure and create pathways for air.

You can boost the breakdown process by adding bokashi bran (available separately), fermented waste from a bokashi bin, or a bucketful of mature compost. An Insulating Jacket is also available separately to provide insulation to maintain ideal internal temperatures. It should be removed in warm weather or the temperature inside the unit will become too hot for the composting creatures to survive.

And finally…

To access your finished compost simply unscrew the hatches at the bottom of the Johanna and remove the compost using the aerator stick or a garden hoe. Alternatively, because the Johanna is a modular unit you can unscrew the upper sections to access larger amounts of compost.

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