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Green Johanna Hot Composter and Food Waste Digester


Gardeners' World Magazine 'Star Buy'!

The Green Johanna is the garden compost bin and food waste digester with a difference.

A hot composter, the Green Johanna recycles all kinds of waste food – even cooked food, bones, meat and fish – into rich organic compost which means you have a compost bin and food waste digester all in one!

Simply install the Green Johanna in a shady, sheltered spot and fuel with a few centimetres of garden waste.

Then add two layers of food waste for every layer of garden waste. To ensure food waste recycling all year round, you may wish to dress your Green Johanna in her winter jacket (purchased separately) if the average outdoor temperature drops below 5°C for several days at a time.

If you love recycling and would like a greener garden, the Green Johanna is for you.

Base diameter:
82 cm
94 cm
Lid diameter :
54 cm
11.4 cu ft/330 litre
9.5 kg (10 kg with box)

Why should you compost organic waste?

A large proportion of garden waste and food scraps collected by local authorities in the UK end up being disposed of in landfill. If you compost you could be helping to reduce the amount of waste buried in landfill and the environmental disadvantages of transporting waste matter to landfill.  Landfill can produce far more methane when breaking down organic matter than a home composter and you also end up with a usable material to put back in your garden.


Why choose the Green Johanna?

The Green Johanna is a superior composter designed so that the contents are well ventilated, given free drainage and kept in a protected environment during the break down process. Its special conical shape helps prevent waste sticking to the inside leaving space for the air to move around. As long as you follow the simple instructions, you should find the Green Johanna easy to use.


What is the Green Johanna made of?

It is made of a durable plastic that resists attack from the elements including extremes of temperature and is expected to last for around 10 years or more.


Does my Green Johanna come with a Warranty?

If your Green Johanna is 10 years old or less, Great Green Systems Limited will replace any faulty or missing parts. This excludes ordinary wear and tear and damage caused by misuse or accidents. Individual parts can be purchased if required - please complete our 'Contact Us' form, and one of our team will be happy to assist.


How do you start?

Since good air circulation is important to ensure efficient operation of your Green Johanna you will need to place inside at the base, small branches and twigs in a layer that should be about 20 centimetres (8 inches) deep. After that you add your garden and kitchen waste.


Can I place the Green Johanna in direct sunlight?

No as the contents should not be allowed to get too hot since this can kill off the beneficial microbes breaking down the contents.


How much waste can it take?

It is designed for a household with up to five people together with the compostable waste produced from an average garden. However since this is extremely variable, if you believe you are filling it too quickly it would be recommended to have a second Green Johanna. Remember a garden produces less waste in winter. Some of the material in summer can be kept to layer in with food waste during winter.


What are the dimensions of the Green Johanna?

It is 90cm (36 inches) across at the base, the lid is 52cm (21 inches) wide and its overall height is 95cm (38 inches). It weighs 10 kilos.


Why are there holes in the base?

This allows naturally occurring insects and worms to gain access to aid the breakdown process. It also lets excess moisture out into the ground.


Where should you locate a Green Johanna?

When the micro-organisms are actively breaking down waste, energy is released. How warm the compost gets depends on what you have put in together with levels of oxygen and moisture. The micro-organisms work at between 5 and 75 degrees. Different micro-organisms work at different temperatures. The optimum working temperature in the compost bin will be around 45-65 degrees.


Do I have to add any chemicals to get started?

No absolutely not! In fact chemicals may upset the natural balance of the system so best avoided.


Can I put kitchen waste directly in the compost without the branches and twigs first?

Yes, but it is recommended that you put one part garden waste and two parts kitchenwaste in to help balance the carbon and nitrogen levels which will make better compost, and the initial loading of small brancjes and twigs improves the airflow and helps your Green Johanna get going more quickly.


Can I mix garden waste and kitchen waste?

Yes. It is recommended that you put one part garden waste and two parts kitchenwaste in to help balance the carbon and nitrogen levels which will make better compost more quickly.


How much of my kitchen waste can I put in my compost?

The Green Johanna will take around 120 kilos per person a year.


Can I still use the composter if I only have kitchen waste?

Yes, if you add layers of of carbon rich material such as sawdust, cardboard and straw etc to balance the nitrogen in the food waste.


What can I put in my composter?

From the kitchen: Fruit, vegetables, dairy products, fish, shellfish, meat,bones, coffee grounds with filter, teabags, eggshells, bread, sauce, soup,egg cartons and so on.

From the garden: Grass, leaves, twigs and branches.


What are rich in carbon?

Sawdust, twigs, leaves and paper.


What are rich in nitrogen?

Eggs, fish and meat. Newly cut grass also contains a lot of nitrogen.

Step 1

Stand the Green Johanna on level soil or grass in a shady corner of the garden. The container should be in as sheltered a location as possible and not too far from the house.


Step 2

The Green Johanna will perform at it’s best when placed out of direct sun light; the more shaded the area the better.


Step 3

Standing the Green Johanna on soil or grass will allow worms and micro-organisms to migrate in and out of the compost and help break down the waste.



You must assemble your Green Johanna before installation


To assemble your Green Johanna, you will need these

philips screwdriver
Philips Screwdriver


Base Unit
Ring 1
Ring 2
Ring 3
Ring 4



Step 1

Place the base of the Johanna on a flat solid surface.


Step 2

Place "Ring 1" (with door openings) over the base unit and screw together.


Step 3

When fitting the rest of the rings together you must line up the "line marks" on the outside of the rings or the screw holes will not line up.


Step 4

Place "Ring 2" over ring 1 and screw together.


Step 5

Add all the rings as above until complete and screw together.

Slide in the doors and screw down tight and add the lid.


Step 6

Your Johanna is now ready for use.


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Why make compost?

The waste mountain is a major problem, yet more than half of our rubbish is biodegradable and can be composted. The nutrients that we take from the earth are now primarily replaced with artificial fertilisers, which are expensive to manufacture. Natural nutrients, which are free and can be found in our rubbish bins, currently lie on a waste mountain, which is becoming ever larger and more impossible to control.

But despite all the gloomy figures about how much we waste and throw away (320 kg of rubbish per person per year), the future is looking brighter. More and more people are starting to make compost, and finding meaning and happiness in turning their rubbish into nutritious compost. We are beginning to participate in Nature's cycle and are becoming conscious about what we buy, use and throw away.


Sorting at source begins in the kitchen

This is where you must begin separating the glass, plastic and metal from the material, which can be composted. Simply add another bin in your kitchen and separate the waste that can be composted from that which cannot. All food waste can be composted: vegetables, fruit, dairy products, bread, bones, fish remains, soup and eggshells. Coffee filters containing coffee grounds, tea bags, household paper, egg cartons, and wilted flowers and pot plants can also be added to the compost. Grass clippings, leaves, twigs, weeds, bark, etc. can also be composted. It is recommended to cut the waste into small pieces, as this gives the micro organisms more surface area to work on, producing compost more quickly!


The stirring stick... an accessory that helps you aerate the compost effectively. It is also an ideal tool for removing the final compost.


No ordinary compost system

Green Johanna allows us to compost all our food waste. This means bones, bread, dairy, eggshell, fish, fruit, meat, soup and vegetables can all be used and composted, as well as coffee filters, teabags, household papers, egg cartons, wilted flowers and dead pot plants.

Green Johanna allows us to make compost all the year round. No matter how cold the outside temperature, we can make compost 12 months a year thanks to the special shape and the winter jacket.

Green Johanna produces the finest quality compost. The final product is fully broken down and appears as a moist, nutrient-rich soil, the ultimate treat for our favourite garden plants.

Green Johanna features adjustable ventilation. With the lockable lid the variations in compost temperature and quality can easily be adjusted and controlled.

Green Johanna is easy to empty. Unlike most compost systems which must be emptied by dismantling or digging from the top.

Green Johanna allows us to draw only the completed compost from the bottom without disturbing the process that is continuing above.


1. How do you start?

Cover the whole base plate with a loose layer of twigs and other coarse garden material to a depth of 10-20 cm. This should be covered with a layer of fine garden waste, followed by mature compost or soil. You can now begin to add your household waste. In the winter, you follow the same process, also adding one or two bucketfuls of farmyard manure or compost from an ongoing composting process.


2. The importance of layering

It is important to layer garden and household waste properly. The best combination is one part garden waste (or soil, planing shavings, sawdust) to two parts kitchen scraps. Layers of one substance should never be too thick. Don't forget to scatter and mix the material as finely as possible, as this helps to speed up the process.


3. Aerating

Mix and aerate the uppermost layer of the compost every time you add new material. This ensures that the micro-organisms, which live and work in the compost, are able to do their job successfully. Once in a while, it is necessary to aerate the compost deeper down. This is done by carefully moving the stirring stick up and down in the compost.


4. Covering new waste

As you add new waste, the compost will shrink. Always cover the new household waste with garden litter. You won't usually have to buy garden litter. It is to your own advantage to make your own from hedge clippings, trimmings from bushes and trees and other garden waste, this can be done by hand or simply by using a garden shredder. This is the best litter for your compost and, during the autumn, you should save garden waste to use in winter.


5. When is it ready and how do you empty it out?

Depending on the conditions the compost will be ready after four to six months. It looks and feels like soil, smells good, is pleasant to the touch and crumbles readily. The easiest way to empty your Green Johanna is to remove the composted material through the two doors at the base. That way, you'll only get mature compost, and you'll avoid having to sort and start the process over again. It's even better if you have two or more Johannas, as you'll be able to let the compost in one mature fully while you continue adding to the other. Try to organise your composting process, so that you have humus ready in time for spring, when you need the nutrients for your plants.


6. Where do you put the mature compost?

The mature compost, which has become humus, can be spread on the earth all year round (e.g. around trees, bushes and on vegetable patches). The compost can be dug in, but if the mulch is not ready, the decomposition process will continue and steal the oxygen from the plants. In the autumn, however, half-ready compost is ideal for digging in to the earth. You can also let the compost lie and mature in a simple container or in a covered heap if you do not need it straight away.


7. There is no better compost than home-made compost

No soil is as nutritious and of such high quality as that which comes from a hot compost and which contains both garden and household waste. The compost produced in Green Johanna is a rich nutrient supplement for your garden. You'll notice the difference in everything you grow: vegetables will taste better and flowers will grow and flourish!


The Winter Jacket... made of foam polyethylene. The winter jacket should be fitted when the average outdoor temperature consistently falls below 5°C, and removed when the temperature is constantly above 10°C.

It is essential that the winter jacket is removable during the process, otherwise the compost will burn, in which event the microorganisms die and the process is halted.