By Conall O’Caoimh
Making good compost is easier than you may think. There is just one really important rule: keep a balance of leafy material (rich in nitrogen) and woody material (rich in carbon). Then the magic can happen. You will know its working as your compost heap will be warm to the touch.
And capturing your own compost rather than losing it to the brown bin will add up over the years and transform the quality of your soil.
The simplest form of composting
The simplest form of composting is mulching – e.g. spreading cut grass or leaves around the base of a plant. This will retain water and suppress weeds and eventually the mulch will decompose and provide nutrients to the plant. No more to it.
Things that help:
The smaller the pieces the faster the process. This is especially true for the woody material – so sawdust is ideal, or branches that have been chipped. Without a shredder you just need a lot more time.
Smaller pieces also rise to higher temperatures that will kill off the seeds of many kinds of weeds.
Digging the compost out of one bin and into the other after a few months will certainly speed up the process, but is a strenuous work out. It is not necessary.
When you empty your compost bin, leave a little at the bottom. The microbes in it will help kick start the process for the next batch.
Things that hinder:
Do not put any cooked waste in an open compost bin – it will only invite the wrong kind of visitors.
Citric fruits are too acidic and will slow the process.
Cordaline and phormium leaves take forever and also bung up the shredder, so they are the one vegetative material I happily send to the brown bin.
Shredded paper is good in theory as a source of carbon, but in practice it forms globs that are slow to break down.
I don’t follow my own advice on this one, but you are best if you can put weeds in a separate place to decompose, so their weeds do not infiltrate your compost.
Not everything has to end up there
Awkward shaped branches that don’t easily go in the shredder I put in a heap out of the way that I call a bugs hotel. I hope some day a hedgehog may check-in.
I put cut grass in under hedging and shrubs where it can take its time to decompose. In the compost bin it brings too many seeds and stops the air circulating. Alternatively use cut grass to mulch fruiting trees.
I use the loppers to cut branches that can be used as kindling for the fire rather than send them to the compost bin.
Occasionally you have to deal with the stump of a shrub or other dense material that would take forever to decompose. It does not need to go out in the bin, find a place under some shrub or hedge where nature can slowly take its course.
Making compost bins
My first compost bins I made of old pallets – until the pallets themselves decomposed. Now I have the sides covered with galvanised iron to protect the wooden frame. In Karl Flynn’s garden you may have seen his concrete-sided bins that look immortal.
Bulk helps the temperature to rise and will speed up the process. About one meter is as deep as it should go. Spreading out a little helps air to penetrate.
The more space you give it, the longer you can leave it to do its own thing. Having three or more sections allows one set to decompose while new material goes to a different bin.
Several kinds of kitchen digesters are available to buy. Most important is one that is sealed so unwelcome visitors will not be attracted. Ours is a ‘Big Pig’ that is a cylinder which can be rotated to mix and aerate the material. It takes all kitchen waste except citric. And within six weeks (two months in winter) we have the most lush and light compost to add to the glasshouse.
Using the Compost
It is all about enriching your soil. Just spread the compost on top of the soil. Winter or early spring is easiest as fewer plants will be in the way and the nutrients will be washed into the soil in time for the growing season.
Watch out over the following month or two and touch it with a hoe as soon as any weeds appear.
This year for my potatoes I have tried out the ‘no dig’ method. I placed the potatoes on the bare soil and heaped a full nine inches of home made compost over the whole bed. I did nothing after that and am now enjoying a great crop, easiest ever