Can you put citrus in compost?

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Citrus fruits are an important part of most peoples’ diets but there are many who worry about the effect that citrus fruit peels may have on their compost. So, here we consider, what some feel, a potential problem and ask: can you put citrus in compost?

You can put citrus in compost. Citrus material is acidic and can make parts of the compost hostile to some of the organisms that we need, to cultivate compost. The acidity from citrus fruits can be neutralised by adding hydrated white lime. The need to add carbon ‘browns’, where there’s citrus, also applies.

Any waste generated from citrus fruits will carry an acidic element. Acidity is going to happen in almost all compost heaps due to the nature of the composting process. It will happen regardless of whether you add citrus material or not.

Putting citrus in compost

Adding citrus waste will just add a little more acidity to the compost. You have a choice. You can either leave the situation to resolve itself, this will happen over time, or you can intervene and add an ingredient that will, literally, neutralize the acidity issue almost immediately.

What can you add to reduce acidity in compost?

The ingredient is hydrated white lime. It’s relatively cheap, safe and easy to use. It’s a powder that comes from limestone rock that’s been heated to a high temperature. It’s then allowed to cool before having water added to re-hydrate it. What we have in hydrated white lime is an ingredient that will neutralize acids.

You can reduce acidity when adding citrus to compost

You need to add a sprinkling of hydrated lime every time you add anything to the compost heap regardless of the type of waste being added. When adding citrus waste, it would be a good idea to add just a little more than you would for anything else.

Some take the view that cutting up citrus peel into small pieces will make a difference. This will speed up the process but the acidity issue will still be there. Citrus peel is, usually, small enough in parts. Cutting it up shouldn’t be necessary if you sprinkle on some hydrated lime.

Should I worry about putting citrus waste in the compost?

There is nothing to worry about when adding citrus peel to compost. When we make compost from vegetable waste there is the safe expectation that it will all turn into compost and that there will be no complications. We can pile up a heap of grass clippings and it will turn into compost. We then add potato peelings, lettuce leaves, carrot tops and peel and it will all convert to compost, over time.

Putting citrus in compost won’t do harm

Citrus waste, somehow, feels different. There is something about the zest and tang of orange peel that sends out a warning that there’s a risk if we add it to the compost. There are, unknown-about, chemicals that, in the minds of many, can only do harm and that it will kill the microbial life forms, in a compost heap.

There’s the suggestion that some of the chemicals in citrus peel can be used as an effective pesticide. Such a suggestion is sure to cause near-panic for some but you need to be aware that the quantities and concentrations that we are handling in a leftover piece of fruit will be very small. It will, itself, break down, become diluted and disperse completely over time without having any adverse effect on the compost. There will be no trace of any, potentially, harmful residues by the time you want to use your compost for growing plants.

Can you put citrus in compost? Yes but add some white lime.

Then we have the surface coating that most commercially grown citrus fruits are treated with. Not many people know it but nearly all the fruit that you buy in the shops has to survive long journeys from all parts of the world. This requires that a protective wax coating is applied to the skin of the fruit. It contains an element that prevents mould from starting.

This is mostly successful but, as everyone knows, we often see the odd piece of fruit that develops a patch of mould on it. This would suggest that the amount of mould-restricting chemicals involved here, aren’t worryingly strong.

The wax doesn’t contain a highly concentrated dose that will preserve the fruit indefinitely. It’s just a mild application that will give it a chance to survive long enough to go from the growing plantation to the store, then to the shop, then to you and allow for a few days for you to appreciate looking at it in the fruit-bowl before you actually eat it.

If you’re in the habit of grating the rinds from oranges and lemons, it’s a good idea to wash them using hot water and detergent. Make sure to rinse thoroughly before grating. It’s not clear if there is any risk from ingesting the protective wax but if you know it’s there it makes sense to make some attempt to wash it off.

There’s a suggestion that the smell of citrus peel in a compost pile may act as a deterrent to undesirable visitors. This may be true if you have a large amount of citrus waste in the pile but you need to question this. If there is enough of an excess of citrus material in the compost to keep away vermin etc. there may be too much on board which may mean the rest of the pile is compromised.

What effect does citrus fruit have on the moulding process?

The early stages of decomposition usually involves mould. Then it progresses through stages that see a full, structural breakdown of all materials that are put forward for composting. Citrus peel is no different. We’ve all seen the occasional blue patch of mould turn up on the odd orange. Having citrus waste of any kind will not adversely affect the moulding of other components in the compost mix.

Citrus waste won’t affect the moulding of compost

The question has arisen about penicillin being generated when mould forms and how this may suppress the actions of microbial life forms that are needed to convert organic waste into finished compost. There may well be a conflict in the immediate area around the focal points where mould is cultured but it will in no way affect the entire contents of a composting mass.

The moulding process will only last for a short while for each item involved.

When moulding has ceased, any antimicrobial substances that have been released will disperse and become so diluted that no lasting effect can happen. This will happen regardless of whether the compost is a heat-generating pile or a cold rot.

The effect of citrus fruit waste on worms

Unless your compost pile is entirely citrus fruit waste worms will not be affected. Worms will only eat material that has reached the required degree of decomposition. This applies to everything that worms eat. They may be interested in some of the early-stage moulds that are growing on the surface of citrus waste, as they are with anything else.

Citrus waste is no challenge to worms in compost

In a balanced composting mass, there will be a varied selection of other, less challenging materials that they can consume. They will only focus on the citrus waste when it has broken down enough. When it’s reached a point of decomposition where they can eat it comfortably, any undesirable substances that may have been generated in the early stages, will have diluted away.

The adding of hydrated white lime will assist the worms when they are presented with citrus waste or any other acidic materials. The lime will neutralise the acids. This will help to accelerate the rotting of the citrus and, therefore, the worms will be attracted to it much earlier than they would have otherwise been.

Related questions

What other uses does citrus peel have?

There appears to be lots of ways that you can make use of citrus peel rather than or before you discard them completely. From chewing it to give you a clean fruity breath to putting bits of citrus peel in with soft brown sugar to stop it from turning into hard lumps.

While we’ve been looking at the subject of all things citrus, we’ve been looking around to see what others are suggesting.

Add citrus peel to tea to give it a fruity flavour.
At the next bath time add some citrus peels to hot bath-water for a fruity fragrance.
Simply put some citrus peel in a pan of water and simmer on a hot ring. This will send out a fruity fragrance that will go through the house.
Half fill a microwave- usable bowl with water and load in some citrus peel. Heat at a high level until it boils. Take out the bowl. After doing this the grease and other residues will be easier to clean using a towel.
You can clean precious metals using pieces of lemon peel. The small amount of acid in the peel will make most metals shine.
Citrus peels, used creatively, can deter a variety of insects. Rubbing citrus fruit peel on your skin will apparently keep them off. If you are troubled by a badly placed anthill, soak some citrus peel in a tumbler of warm water. Pour this into the mound, it will apparently persuade them to leave.
If you want to get a fire going, then, citrus peel will make good kindling. It’s not clear if you need to dry it first. If it will burn as moist peel, then, this is probably due to the oils that citrus peel contains.