What do we mean by “yacky”? Well, anything on the “don’t compost this” list really – if you’ve used your toilet tissue to wipe your nose or your bum, it should go down the toilet rather than in your compost heap. It might attract unwanted pests to the heap or could be harbouring nasty bacteria or pathogens which might not get broken down composting process.

You should bin it if you’ve used it to clean up most pet waste or oil spills, or used it in connection with chemical cleaners/agents too – that’s not stuff you want in your lovely compost.

Toilet paper with a bit of wee on them are fine though – you can compost that (as long as the producer is healthy). Ditto tissues used to wipe up a little bit of blood.

The inner cardboard tube can be composted too.

The plants are, obviously, just vegetable matter so they will compost down but in a basic garden compost heap, it’s probably better to avoid them.

Tomato vine stems can be a bit tough, so don’t break down as quickly as everything else around it (some people combat this by shredding them first) and seeds from stray tomatoes left on the vines at the time of composting might lead to rogue plants cropping up wherever you spread the compost – if they weren’t worth picking, chances are their children won’t be either.

Most importantly though, most basic compost heaps won’t get hot enough to come close to killing diseases or mould/fungal spores that the plant maybe harbouring. Some problems can linger in the compost for several years, potentially causing serious damage to future crops – not just tomatoes but other plants in the Solanaceae (nightshade) family too (including potatoes, bell peppers and chilli peppers, and aubergines/egg plants).

So in brief, you can compost tomato plants but if you’re new to composting, you’d probably be best not doing so.

Also see: Can I Compost Tomatoes?

They are, of course, just vegetable matter and will rot down fairly quickly. However, like tomato plants, they can harbour diseases/fungal spores that are not completely broken down by the composting cycle, thus potentially damaging future crops. (Not just future potato crops but anything in the Solanaceae family, which include aubergines and peppers as well as tomatoes.)

Little tiny tubers left on the plant also have a tendency to regrow in the warm, nutrient rich conditions of a compost heap – some people like these “volunteer” plants but others think the inconvenience and risk of disease just isn’t worth it.

Many grow-your-own people burn them rather than composting them and some allotment associations have special bins for collecting this type of risky green waste.

In brief, yes, they can technically be composted but in basic heaps, it’s probably not worth the risk.

Also see: Can I Compost Potatoes?

What do we mean by “yacky”? Well, anything on the “don’t compost this” list really – if you’ve used your kitchen roll to clean up most pet waste or oil spills, or used it in connection with chemical cleaners/agents, then you shouldn’t compost them. The goop might attract unwanted pests to the heap or could be harbouring nasty bacteria or pathogens which might not get broken down composting process.

Kitchen roll or paper towels used to clean up general food mess are usually fine – unless they’re completely saturated with something from the “no” list, they’ll probably breakdown before it becomes a problem. Ditto paper napkins – as long as they’re not too greasy.

The inner cardboard tube from rolls can be composted too.

They’re just beans in a tomato-y sauce so will rot down quite quickly – but the salt and other flavourings may attract undesirable vermin to an open heap. In a pretty enclosed bin, they’ll probably be fine.

As for wormeries, worms are not a fan of baked beans (they can’t make toast to accompany it, so what’s the point?) so it’s best to leave them out for fear of offending your wiggly, composting friends.

Real wood

Since it is a natural product, real wood will decompose into lovely humus – but anything bigger than twigs will take a LONG time to rot down.

In the meantime, it’ll probably clog up your compost heap, making it difficult to turn over and/or extract other finished compost.

If you do want to compost wood (rather than using it/burning it), it would be better to have a dedicated space for it elsewhere in your garden. In the (many) years it’ll take to rot down, it’ll serve as a playground for all sorts of beneficial insects rather than just getting in your way.

Some councils pick up wood (such as large logs or branches) as part of their green waste collection service. Alternatively, people with wood burning stoves will love to get their hands on your wood (ahem) – offer it on a local noticeboard (either offline or online) and someone will probably be able to collect it within a few days.

Hardboard, plywood, particle board and MDF

Fibreboards are almost definitely a composting no-no.

Hardboard is sometimes just compressed wood fibres – that can be composted – but it sometimes includes resin as a binding agent. As it is hard to tell which is which, it’s probably best to leave it out.

Plywood, particle board and MDF always use synthetic binding agents so dust from those should definitely not be added to a compost heap.

Also see: Composting wood shavings and sawdust

What types of water NOT to add

Basically, don’t compost any water that has been mixed with anything on the “don’t compost” list.

Soaps and other chemicals are bad news for a compost heap. They will kill the delicate microbes that are busy doing the composting work — most of the cleaning chemicals and soaps we use around the home are purposely design to kill bacteria and the like but in a compost heap, those guys are our friends!

Whatever chemicals or other pollutants are in the water will also contaminate the resulting compost – possibly not such a big problem with a bit of soapy water from washing your hands but more of a problem for things like petrol, paint or fecal matter — not things you want getting into your veg bed!

Stagnant water, even if it was clean to start with, should not be composted because of the risk of Legionnaire’s Disease and because it also can inhibit our friends, the composting microbes.

Flood water also shouldn’t be composted – unless you know for sure that it hasn’t come into contact with any nasty substances. (Flood water can pick up all sorts of petrol-y substances from roads and in a bad flood, sewerage can flow into river courses etc.)

What CAN be added

Basically, any water that is either clean or only mixed with things that can be composted.

Water from cooking – such as from boiling pasta or vegetables – can be added but only if it is free from oils (cooking, butter or animal fats) as they can attract vermin to the pile. (You can also use that water in stocks, soups and baking – see our water page on Recycle This for more information and ideas.)

How to add water to a compost heap

As mentioned at the start, moisture is an essential part of the composting process. Some people choose to leave their bins or heaps open so they can soak up rainwater as they go, but if you’ve got a lid or a covering, you will probably needed to add some liquid at some time or another (especially if you’re adding a lot of browns)

When adding water to a compost bin or heap, add it to the centre of the pile and stir it through if you can to get the maximum benefit – that’ll stop it simply dampening the top layer and make sure the often-warmer middle won’t dry out.

Do try not to over-wet the heap though. Overall, the compost should be moist not wet. This is particularly important if you’re using a sealed compost system – most purpose-bought compost bins have drainage holes (or a completely open bottom) to allow excess water to drain out.

The flesh of the fruit will rot down very quickly but the stones will take a lot longer – if you intend to use your compost in your garden in the near future, the stones might be annoying lumps.

You can read about other things to do with olive stones on How Can I Recycle This?

You can compost:

These ashes are fine in small amounts – but be careful as it can very quickly made the heap to alkaline. (This might be desirable for balancing out acidic compost heaps or acid soils but in most circumstances, it’s better to keep it neutral overall.) Mix it into the contents of the heap to avoid the small particles being blown around on the wind.

Make sure ashes are thoroughly cooled before adding them to your compost heap, otherwise dry materials in the compost may fire risk.

These ashes can also be used “neat” on the garden as a slug deterrent and soil fertiliser, or reused in other ways too.

But don’t compost:

All these types of ash contain materials that are harmful to plants or animals, or in some cases, the wider ecosystem.

If in doubt and especially if you’re using your compost for growing edibles, leave it out.

Basically, as you might have guessed, natural fibres will compost down but synthetic ones will not.

Clothes made from synthetic fibres – such as acrylic yarn, polyester/nylon fabrics or microfibre fleeces -shouldn’t be added to the compost heap as they won’t break down – they’ll just clog up your compost heap.

Items made from entirely from pure wool, cotton, silk, linen, hemp and ramie (or a blend of any of those) will compost down – but they will all take a while (their durability is one of the reasons why we make them from them rather than, say, paper). Tear them up to help them rot down quicker.

Keep in mind that many items that claim to be made from 100% natural fibres, like cotton t-shirts or jeans, may still use polyester “cotton” for their sewing thread (since it’s cheaper & strong than actual cotton thread). That won’t break down so you might end up with some strings left in your compost heap – once everything else has rotted down around it. (They should be relatively easy to pluck out though.)

Blends of natural and synthetic fibres are more of a judgment call, depending on the mix. If it’s more synthetic than natural, then almost definitely leave it out but if it’s only includes a little synthetic material, then you might consider adding it. The synthetic part might break up but will still not break down – you might be left with either lots of little tiny pieces of it throughout the compost or some longer strings, depending on how the synthetic material was incorporated. If you want to keep your compost heap free from synthetics then obviously leave them out, but if you’re not so fussy, you can add them and pluck out longer strings afterwards.

Don’t compost any clothes that are stained with things from the “do not compost” list – like paint or engine oil – as you don’t want that in your compost heap.

If you’re using your compost for veg growing, you also might want want to leave out natural fibres that have been extensively dry cleaned or include heavy prints to avoid residue chemical contamination. And definitely avoid composting items like t-shirts which have slogans or designs that seem to sit on the fabric rather than ones that are part of the weave or have soaked in – that’s usually a sign that it’s been printed with PVC inks and plastics like PVC will not break down.

Clothes made from natural fibres are a “brown” in composting terms – make sure you add them alongside fresher, wetter items (like veg peelings or garden cuttings) to ensure they break down in a timely manner and your heap stays balanced. And don’t overwhelm your compost heap with old clothes – no more than 25%.

Before you think about composting any old clothes though, do try to reuse (or allow others to reuse) the items first. Donate still wearable items to charity shops/charity collection bins or sell them on eBay. Cut up old cotton items to use as cleaning rags. If you can sew or are the crafty type, you can upcycle the item as another piece of clothing or use the fabric as a material for other crafts. Finally, textile reclamation specialists (aka “rag men”) take old clothes and reclaim the fabrics for industrial use (such as for insulation). All of those are better reuses for fabric than simply composting them.