'Peecycling' is the latest sustainable gardening trend – but should you be peeing on your compost to improve it?

Making compost at home is a cheap and simple way to boost your soil and give your precious plants all the nutrients they need to grow big and healthy. 

Getting the mix of green and brown materials right is key to great compost. You can use kitchen waste, grass cuttings, leaves, shredded newspaper and even coffee grounds. One other unexpected, and highly beneficial ingredient, you can add to a homemade compost pile is human urine. 

Many may turn their nose at the thought of being able to put urine on compost, but it is a great source of nitrogen and can even speed up the decomposition process of your compost. Also it is readily-available, free, and incredibly easy to add to any compost heap.

Drew Swainston

Drew is a former professional gardener who worked primarily for the National Trust in the UK, along with spending time in productive kitchen gardens. Composting was always important in the places he worked at and each had bays to produce their own compost in-house for use around the gardens.

Benefits of urine on compost

Composting is an important part of any garden as it allows gardeners to take what could otherwise be seen as waste materials and turn them into something that feeds and nourishes plants. The addition of compost can boost all soil types, helping you get beautiful blooms or bumper crops in your backyard or vegetable garden. ‘Peecycling’ is simply another aspect of this, that is the term is given to recycling human urine and using it to help feed plants and crops.

Human urine is beneficial as part of a composting system as it has a high nitrogen content along with containing potassium and phosphorus. These three are the main nutrients that are essential to healthy plant growth and ones that you see referred to as NPK on plant fertilizer labels.

Urine fits in as one of the ‘green’ layers in composting, along with the likes of grass clippings from mowing a lawn and kitchen waste, that all contain nitrogen. However, the higher concentration of nitrogen in urine acts as a compost activator and actively speeds up the process of composting. It can be highly beneficial to give an extra boost to a compost heap that is decomposing slowly, a new heap that needs to initiate decomposition, or for breaking down coarser organic matter like leaves.

Alexia Allen from Hawthorn Farm, a garden and homestead consultant in Woodinville, WA, describes urine as ‘a fantastic nitrate fertilizer’ and adds that ‘of course the price is right’. She claims she would ‘hundred percent’ recommend people to put urine on compost heaps at home.

‘So many home composts are not strong enough when it comes to plant-fertilizing power, and adding urine is a fantastic way to boost plant nutrients without having to pee directly on your garden, and to capture your personal nutrients during the season the plants aren't actively needing nutrients,' adds Alexia. ‘So many people lament the fact that they don't have livestock to add fertility to their pile, and I reply that they can be their own livestock.’

Another benefit of using urine is it helps keep the compost heap moist. The bacteria and fungi in the compost need moisture to work effectively and a dry heap will stop breaking down. 

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How to put urine on compost

There are a few different ways to put urine in a compost heap and how you choose to do it may come down to personal preferences and the location of your compost heap. 

The simplest way is to urinate straight on the heap itself, though this may obviously be easier and more preferential for some rather than others. Ultimately it may depend on how private your heap is or how bold you are as a person. You can always urinate into a container to add to the heap, though make sure to do this relatively quickly to the heap – ideally adding it to the heap within 24-48 hours.

There are other ways to add urine in compost without it being put directly onto the heap itself every time. One is to add urine directly to straw until it decomposes and then mix that into your compost heap. An example of this was previously done by the National Trust in the UK. At its gardens at Wimpole Hall in Cambridgeshire they introduced straw ‘pee bales’ that male workers could relieve themselves on (outside of the public opening hours) that were then added to the garden’s compost heaps.

You can even harness the nitrogen-rich power of the urine by making compost without an existing heap being utilized. Alexia Allen from Hawthorn Farm recommends a method of making a big pile of leaves and then adding urine to it over winter. By spring she claims it will be ‘extra-rich and crumbly and better than your average compost’. This can either be added to a compost heap or put directly onto the garden as a rich leaf mulch.

Danger of too much urine in compost

Human urine is sterile when it leaves the body and safe to add to compost. The only time it tends not to be is if a person has a urinary tract infection, while some medications can also be present in trace amounts so caution should be taken. Urine should be added in moderation to compost as it does have high salt levels. While humans will urinate several times a day, it is not necessary to add it all to the compost heap – too much is not always a good thing.

The main issue to consider when putting urine on compost is the ratio of green and brown materials that you have in the heap. Ideally, you want a 2:1 ratio of brown-to-green. Too much nitrogen-rich green material will see your compost heap emit a smell of ammonia. As urine is so rich in nitrogen, you must ensure that you add even more brown material to counteract it. So make sure to have lots of sawdust, leaves, cardboard or straw to add too, that way you end up with perfect compost that makes one of the best types of mulch.

Other uses for urine in the garden

Urine is perfectly fine for compost, however it is too strong in nitrogen to add directly to many live plants. Brian Campbell, a degree holder in Environmental Studies, founder of Water Filter Guru, and avid gardener, warns: ‘Human urine is abundant in phosphorus and nitrogen, which are essential nutrients for healthy plant growth. However, the amount of urine should be regulated depending on the plant. Some plants can tolerate undiluted urine, while others may need diluting to avoid negative consequences.’ Though it may be tempting to give some of your plants a direct boost of nitrogen, maybe it's best to keep the pee for the compost heap.

Looking online you do see some other recommendations for using pee in the garden. Some recommend watered-down urine diluted with 10 parts water as a great feed for plants in container gardens, while others claim you can put urine on mulches like leaf mulch or wood chip to speed up their decomposition. 

While it may sound a bit off-putting to many gardeners, the benefits of putting urine on compost mean it should really be considered. Not only is it rich in nitrogen, but it can also speed up the composting process – there are two big positives that it offers. It is a free and natural way to nourish your garden and can help you get more blooms on your flowers or better crops. 

If you are planning a kitchen garden, then it may be worth considering putting urine in compost. This may be something you have never thought about before, but the benefits are real and seriously worth taking into account.