Nitrogen-rich materials, also known as greens, are anything of animal origin, or recently harvested plant materials, even if they have now withered. The exception is coffee grounds which may look brown, but they act  as green.

Not many of us have heaps of peanut shells or seaweed just crying out to be composted.  Obviously, we compost what we have on hand. For most of us, that is garden debris and kitchen scraps.  Note that I don’t call them waste, because, remember, they are only waste if you throw them away.

Most books will tell you that there are things you mustn’t compost, such as meat scraps, oils, pet litter, egg shells, orange rinds.  Everything of organic origin – with the unfortunate exception of plastic- CAN be composted.  Sometimes you may choose not to.

Meat scraps are a great source of nitrogen, but may attract dogs and other animals.  If you make sure that you bury them deep in your pile, they should not be a problem.  Alternatively, you can process then in your blender into a compost soup, so that there is just not enough for an animal to get its teeth into.

Earthworms apparently do not like oils and fats, but they can safely be added to the compost pile in small quantities.  This is much better than tossing them down the drain, as fats are the biggest problem that municipal waste management systems contend with, as they tend to clog the drains.

The strongest argument against pet excrement is that it may contain pathogens. If you have healthy pets, you probably don’t have a problem at all and this is only a potential problem if the compost is to be used in the vegetable garden. The problem can be overcome in four different ways:

Ensure that your pile reaches 131º Fahrenheit for at least three days (see how to compost)

Leave the pile to mature for at least a year

Keep a separate pile for ornamental plants only

Bury the excrement in a quiet corner of the garden

 Clay-type cat litter will sit around for ages (who in their right mind will add clay to soil that you are trying to lighten?) but there are “green” litters made from corn or pine or newspaper that will compost beautifully.  Newspaper, however, does not work very well as a litter.

Eggshells can be put into the compost heap with no problem at all.  They do break down slowly, but roughly crushed they add some structure to the pile.  For the most part, I do not put my eggshells in the compost, but that is only because I have a better use for them.  I crush them and use them as a mulch under plants that slugs love – zucchini, cucumbers, hosta.  As long as the leaves don’t touch the soil, the slugs will not be able to get to them as the eggshells rip them to pieces.  Gruesome but effective.

I also don’t put citrus rinds into the compost, again, not because I shouldn’t, but because I have a better use for them, too: I put them down my garbage disposal to clean it out. I don’t use it much, but there are times when it really is the best solution.  If I knew that my municipality composted sewage sludge, I would feel a lot less guilty about using a garbage disposal unit.

Little aside here.  When we redid our kitchen and installed the garbage disposal, I asked the contractor whether it would be possible to divert the water to a barrel, so that I could then use it on the garden.  Absolutely not, was the answer in 1994.  But it can be done. What a wonderful solution to those chicken bones and other supposedly uncompostable kitchen products. And if you use a permeable bag inside your barrel, you can lift that out and put the solids in the compost, while the enriched liquid can be used for watering purposes.

Surfing that wonderful resource, the worldwide web, I came across a list of “163 Things You Can Compost” by Marion Owen, co-author of Chicken Soup for the Gardener's Soul.  Some of these items are a real stretch, but their presence on the list that follows underlines the fact that you can compost anything organic, and that it is as easy to toss them into the compost bucket as it is to toss them into the garbage.Selected items include:

 Blood meal and bone meal – both of these will boost your compost activity, but I feel that going out and buying them at the Garden Center is somewhat like buying fabric to cut up to make patchwork quilts. The spirit of both patchwork and compost is all about using what you have on hand, or which you can get easily, free or in trade.

Food scraps  - dig them into the pile, or cover with a good layer of brown material.  Odor is not usually a problem, but flies can be.

garden debris – the mainstay of the home compost pile.  Reduce the size as much as possible, utilizing the lawn mower, weed wacker or machete, especially for woodier clippings.  When pruning, it takes very little extra time to cut the twigs and branches into 3-4” pieces.  You will obviously have bigger pieces which require a lot of work to reduce them to compostable size.  If your city collects and composts yard debris, use their service.  If not find a secluded part of the garden, behind or under bushes where you can deposit all the larger pieces that do appear at regular intervals.  Just leave them there for a couple of years.  They, too, will break down over time.  Or dig a pit and dump them all in there.

grass clippings – the best reason for having a lawn, perhaps the only reason for having a lawn.  For the most part, however, the clippings should be left on the lawn.  As long as the clipping are not longer than an inch and a half, these will be the only nourishment the lawn needs.  From time to time, however, you may want to rake up the lawn clippings to add to the compost.  Just make sure that you don’t layer the grass so thickly that it excludes air.  In an airless (anaerobic) situation, grass clippings quickly become slimy and smelly.

hay – best used in a hot pile, as it will contain many seeds.  Actually, I don’t find seedlings in the compost to be a huge problem.  Small seedlings are very easy to pull up.  Just leave them on the surface of the soil as a mini green mulch.  I don’t cultivate the soil, I just brush the baby plants aside.

Rake all your leaves on to your lawn prior to your last mow of the season.  The combination of chopped up leaves and grass clippings makes perfect compost.  Pile them all up, and by spring you will have a very useable product.  If you don’t have enough trees, drive around the neighbourhood and pick up bagged leaves to stockpile an use during the summer.

urine – a readily available, mostly sterile, highly “green” innoculant for the compost heap.  Unless you know that you have a urinary tract infection (and believe me you know!) your urine is a free, pathogen-free, everything free resource, easily collected and just waiting to be used.  Of course, it is easy for the men in the household to pee in a bucket.  But, if one takes a cue from the Japanese, even the women can contribute.  Japanese toilets – holes in the ground over which one stands – were obviously developed with kimono-wearing women in mind.  Imagine how difficult it would be for a woman wearing a traditional kimono to use a western-style toilet. But standing, straddling the hole, works very well.  I wear a sort of kaftan to sleep in, a loose fitting garment, to the ground.  I can stand over a bucket on the deck in the early morning, and I guarantee that no neighbor who happens to see me has any idea that I am peeing into my compost bucket.

One very persistent weed is jewelweed, or impatiens capensis.  This can really take hold in a garden, but looking on the bright side, it has three really useful attributes. First it is an effective natural herbal  antidote for poison ivy, poison oak,  stinging nettle, and other irritants. 

Second it makes fabulous compost, breaking down almost as you look at it.  If you catch it before it goes to seed, you will enhance your heap and reduce the number of plants popping up next year.  However it is almost worth leaving a patch in a secluded part of the garden just to feed the compost heap.  Japanese beetles love it and thus its third use is as a decoy plant, meaning that the beetles will congregate on the jewelweed where they can be picked off by hand and dropped into a jar of soapy water, in which they rapidly drown

Purple loosestrife is another very effective decoy.  I don’t feel bad about keeping this invasive alien in my garden because the beetles eat all the flowers and it never sets seed.

Two other plants that are well worth cultivating for the compost heap are comfrey and borage.  Borage is an annual.  I believe that you can eat the leaves as cooked greens, but they are hairy and to my mind totally unappealing.  The beautiful blue flower is the reason I planted borage in the first place.  Not only is it very pretty, but it is an essential ingredient in that quintessentially British cocktail, Pimms, as drunk at the Oxford and Cambridge Boat Race and the Henley Royal Regatta and similar events that were at the heart of the Empire.  They are also very attractive in salads and as a garnish for sandwiches or cheese and crackers.

However, as borage is a vigorous grower and prolific seeder, you are going to have far more flowers than you are ever going to use.  Excess plants add greatly to your compost mix.

Comfrey is a perennial, which just keeps on growing.  It is hard to get rid of, as any small piece of root left in the soil will produce another plant.  But it doesn’t set seed easily, so is not invasive, and it is so beneficial that you really won’t want to get rid of it.  I was introduced to comfrey back in South Africa by a somewhat loony friend who was into organic gardening when Robert Rodale was still in short pants.  The plant’s common name (among others) is boneset, and there is strong evidence that it is effective in promoting rapid healing of broken bones.  Helen, the loony friend, used it to treat her cook’s leg, which had a wound that simply would not heal.  She applied a compress of crushed leaves, and ta-dah, the leg was fine in two shakes of a duck’s tail. 

We were sure that she had exaggerated, but the University of Maryland Medical School notes Comfrey (Symphytum officinale ) is used to treat wounds and reduce the inflammation associated with sprains and broken bones. The roots and leaves contain allantoin, a substance that helps new skin cells grow, along with other substances that reduce inflammation and keep skin healthy.  Whatever its merits for humans, comfrey tea is thought to be a wonderful tonic for ailing plants: “Place a bunch of chopped comfrey leaves at the bottom of a bucket. Weigh down with a brick, fill bucket with water, and cover for three weeks before diluting, one part 'tea' to 10 parts water.”

This brew is said to produce a fertiliser with more potash and nitrogen than commercial feeds.  Again, this may be an exaggeration, but it will do none of the harm that commercial fertilizers may. The leaves can be harvested three or four times a season and put in the compost heap a few at a time.  (Like grass clippings, they will go slimy of there are too many of them.)  They can also be allowed to wilt and then be applied as a mulch for tomato plants.

In general, you should try to get to weeds before they set seed, as this reduces the (slight) nuisance of having seedlings come up wherever you have used your compost.  More importantly, plants that have not yet set seed tend to be less woody, and thus they break down faster.

Weeds are so important that there are times (especially in the spring) when you don’t have enough in your garden, and may find yourself offering to weed other people’s gardens!  This is a great way to make friends while making great compost.