Composting Events and news

9. Aug, 2018

Hot Composting Apples

It is becoming customary to celebrate Apple Day with the communal pressing of apples to make juice or drying them to make apple chips  Many of the windfalls  will not be suitable to eat or drink,but  could be composted, and I felt it might be useful to expand the advice I have previously given on composting apples. 

Apples and other fruit such as pears, banana skins, strawberries, peaches and all melons, can normally be added to the composting or worm bin as and when they are no longer suitable for eating and this includes the occasional windfall during the summer months. Chopping the apples will of course speed the composting process.

 Hot Composting Apples

 Where there are a lot of apples I believe it is best to use a bin and to layer them with browns and continue making alternate layers of apples and browns until all the windfalls have been used. If you only have a few trees it might be better to collect the apples in a storage container i.e. a bucket or bin so that you have enough to make several layers about 4” thick at the same time. If possible, other greens should be added at the same time as the chopped or pulped apples to introduce air spaces and variation into the green mix.

 Creating the correct green brown ratio is important to prevent the apples fermenting and producing an unpleasant smell. One-part green to two-part brown material is traditional recommended although many composters settle for about equal quantities. The RHS suggest that apples should be no more than 20-25% of the total compost material. (  Layering is not essential but in dealing with a large amount of fruit it does make it easier to get the initial green/brown balance right.

 Although autumn leaves are normally used to make leafmold they do make an excellent component of the brown layer when dealing with fruit. Sawdust from a vegetarian pet, or chicken can also be added. I also add shredded computer paper

 A shovelful of finished compost from an adjacent bin, garden soil or manure can also be added to kick start the microbial activity that will turn the apple waste into quality compost. As with most hot composting systems water the bin or the browns at the start of the process and at any time that it looks dry.  Turn the compost mix to aerate it and cover with browns as this will reduce any smells from the bin and reduce numbers of fruit flies when the lid is removed, or heap uncovered

 For the first week the material benefits from being turned daily to aerate the mix ensuring that microbial activity heats the content.  When aerating move the material on the outside of the pile toward the centre. Reduced frequency of mixing as the effect decreases. (See the section on hot composting) if you have a thermometer monitoring the temperature it can provide additional interest (especially for children).

Do continue to check the compost condition weekly. If it becomes to dry it will stop working while if too wet anaerobic bugs will take over and the temperature will fall, and the smell will increase.  If dry add water a little at a time, if wet add more browns e.g.  dry leaves.  After two or three months the compost should be finished dark brown in colour with an earthy smell and no apples identifiable.  

 Cold Composting Apples

 If you have fewer apples and intend to add them to a bin already in use a simplified technique can be used, If the apples are whole chop the apples with a spade and add to the bin to make a layer two or three deep. Cover this with a wet leaves, bedding from vegetarian pets, rough compost or old straw. Repeat the process adding apple and brown layers until the apples have been used. Finish with a layer of browns to reduce odours and insect pests. Using this cold composting process, it may take up to two years to produce good quality compost.

 Diseased fruit

Often windfall apples will be diseased and although cold composting will not  reach temperatures that necessary to kill the more persistent pathogens, they are suitable for disposing of material infected with fungal diseases such as powdery mildews and rusts.

Apple Scab is caused by a fungus that infects both leaves and fruit it is not suitable for cold composting, but it will not survive hot composting at above 60-70C

 In some countries the apple maggot, is a problem and its spread can result from cold composting at home or on the allotment. If apple maggot is a problem in your area check the apples before adding them to the bin. Infected fruit will show damage throughout the flesh and turn brown and mushy as the   maggots burrow throughout the apple for up to   up to 30 days. This widespread damage enables apple maggot infection to be distinguished from that caused by the more common codling moth, which burrows straight to the apple core leaving most of the fruit undamaged.

Apples that appears to have maggot damage it should be bagged in plastic bags and sent to a landfill. There is more detailed information at Washington State University,  Whatcom County Composting Factsheet which is available at:


More information on composting apples can be found at

The next blog will be a short update on composting apple pulp

8. Aug, 2018

Human hair can be composted it has a high nitrogen content making it a good “Green”, it also contains hydrogen, oxygen, carbon and sulphur according to Rodale this is the same as Bone meal.  Hair decomposes slowly and can form a mat easily in the bin.  Hair from pets and other animals can also be composted. Dog hair can be obtained both from home grooming and may make up a considerable proportion of the waste in the vacuum cleaner (I have two Clumber spaniels who shed throughout the year) providing a constant supply of vacuumed hair.

 Hair can also be obtained from local hairdressers or dog groomers but do be aware that any waste that comes from a commercial activity is business waste and this includes waste produced from running a business from home. See below. (Be aware that Regulations may apply to disposal and carriage of trade waste)

Composting Hair

Hair can form lumps (mat) when being composted unless added to the bin in a small quantity to form a thin layer or mixed with other Greens either before or as it is added to the bin. The bin should be aerated every two or three days for the first week or to speed the composting process the more hair being added at any time the more important it is to mix it well to prevent compaction which might reduce air circulation and create anaerobic conditions. Be care not to overload the bin with hair. It should only form a small proportion of the Green material being composted.

Rodale describes a technique for composting hair developed by William Stafford which will deal with larger quantities. The Stafford recipe uses 10 pounds Hair cut ¾ long, 20 pounds of cottonseed meal and 11/2yards of leafmold. This is mixed and watered and composted for 30-60 days being turned regularly until rotted. It was then used as a mulch round rose bushes.

Environmental writer Janet Harriet quoted on the GRIST website suggests that dyed of bleached hair “may introduce toxic chemicals into your compost,”

Research on the composting of tannery hair waste found that the optimum conditions were:  temperature 40 - 50 C, moisture content 55%, pH 7.0 and a carbon to nitrogen ratio of 35:1. As this is the case hot composting will be more effective than cold

 Hair can also be used as a feedstock in a wormery dog, human and cat hair is regularly used by home composters. Hair mixed with cattle manure has been used very successfully as a feedstock in the wormery creating compost within a couple of months.

The legal position on carrige of trade waste such as hair from a dog groomers or barbers is given on the main website


31. Jul, 2018

The first weeks results of our Rotbot experiment to show how the C:N ratio affects the rate of decompostition has been published on the carryoncomposting Rotbot page  Rotbots & C:N ratio

 5 bottles were used containing different ratios of Greens and Browns : 100%, 25:75%, 50:50 75:25%and 100:0%). The higher the ratio of Greens the faster the process 

The next stage is to repeat the experiement using more tightly packed material which should retain more moisture

17. Jul, 2018

Decomposition rates using different ratios of Green and Browns.  

 Carbon and nitrogen are the most important of the many elements required for microbial decomposition of organic matter to produce compost.  The C: N ratio (Carbon: Nitrogen Ratio) is often referred to in composting books and websites, although less emphasis is placed on calculating the precise ratio of a mix than was once the case. Home composters are now advised to use equal amount of Greens and Browns rather than a calculated mix to provide an “ideal” C:N ratio of 25-30:1.

 This project, using Rotbots, should show the temperature during composting using Greens and Browns, in different proportions and together with observation of the state of the decomposing material, will show whether the ratio of Greens (nitrogen rich) and Browns (carbon rich) will affect the microbial activity in, and the rate of decomposition of, the organic material in a Rotbot. The temperature should be recorded using a soil or compost thermometer. 

 When choosing the materials to use in this exercise it is suggested that, if this is forming part of a class experiment, Greens and Browns with a range of C:N ratios are used by each group to see if materials with different C:N ratios will react differently

15. Jul, 2018

Composting Spent Hops

Composting spent hops is not new but until recently they were a material available to relatively few home composters. With the increased in craft brewers this has changed. Many bag their spent hops and made available for collection free of charge to anyone prepared to collect it. An offer frequently taken up by allotment societies and gardeners.

Spent Hops can be composted or used directly as a mulch they are nitrogen-rich.  To achieve the right C:N ratio a good quantity of Browns need to be provided and if the hops are provide/composted while wet they will need sufficient carbon rich material, such as shredded paper, sawdust or woodchip, to help absorb the water and prevent anaerobic decomposition. Compost junkie recommends 1 part spent grains/hops to 3 parts carbon material. (


Hops are toxic to dogs and while hop flowers have a bitter taste spent hops are likely to taste better. Details of symptoms can be found at  ( ( . Becuase of their toxicity  I do not recommend using them as a mulch or on an open compost heap, or bin, in any area to which dogs have , or might have, access.