Ulla’s Guide to Allotment Composting
Compost feeds the soil, improves drainage, and breaks up heavy clay.
You have grown stuff to eat or look at, so why not let the leftovers help grow bigger and better crops next year. Time spent composting will reward you next year.
Easy composting:
Composting does not have to be complicated – simply add everything SUITABLE to be composted to a pile anywhere. After 3 months turn the top of the pile into a new one, and use the material composted underneath.
Things not suitable for composting are:
Seeds
Roots from biannual weeds/ taproots
Diseased material
These should always be disposed of away from the site. Mostly you will just have a small bag of this material which can be disposed of with the black waste at home if you don’t have a garden bin.
This is the most basic way of composting, and can be done on a spare bit of ground anywhere on your plot. The worms from the soil and woodlice will do most of the breaking down of the material, but the temperature in your pile is unlikely to kill any seeds, roots or diseases. Also large items might not break down in 3 months but can be added to the new pile to continue to break down.
You can dig a trench and put your composting material in and after a while or before winter, then cover it with soil. This will be a perfect bean or pea growing space next year.
Fairly easy composting:
Composting in plastic bins or enclosed areas such as a pallet enclosure. Again fairly easy in what you can add to the compost and the unsuitable items are the same as above. The temperature is likely to get higher if materials are added regularly, so some seeds might be killed this way. Worms and woodlice as well as micro organisms and soils bacteria is responsible for breaking down the compost, and I shall explain how you can encourage this later.
The concern about compost bins are that it might attract vermin. The plastic bins are often open at the bottom though you can get them with a sealed bottom. Pallet enclosures are also open at the bottom. You can either place some slabs under your composting area or some fine metal netting if you are worried about mice or rats. You can also add netting to the pallet enclosure sides to prevent vermin.
I use both types of bins. I put the slower composting stuff in the plastic bins such as kitchen scraps and teabags, and empty them once a year. The rest goes into the wooden enclosures, and I get roughly 3 lots of compost a year.
The composting process requires some air and moisture. In the plastic bins it is important to open the lids now and again, and maybe even give the top layer a bit of stir with a fork to let in some oxygen. The compost in plastic bins can become quite wet and perhaps smelly at times, and that is often a sign of lack of oxygen and brown materials. I shall explain about brown materials later. The pallet enclosures do not suffer from this generally, and might even become too dry in the summer, so might need a bit of water to “get cooking” again.
To help the composting process, it is advisable to chop up your material before placing in the bins. Simply the smaller the pieces the quicker they break down. I aim for 2 inches for stems, but mostly put in the leaves whole. If I add root vegetables I chop them up to 1 inch pieces. I keep an old chopping board and kitchen knife for this purpose.
Mixing layers of different materials will also help the micro organisms, and there are lots of ways of mixing “green and brown material” to speed things up. The simple way is to sprinkle a bit of your soil from your plot onto the pile at regular intervals, as it contains lots of micro organisms.
Turning the pile once or twice during the process also can speed things up and increases oxygen for the micro organisms. I have two compost bays, and I only turn once every 2 to three months, and not at all in the winter.
Certain plants act as accelerators and improves the quality of the compost: Grass clippings, comfrey, clover, nettles and alfalfa. I grow comfrey just for composting (and comfrey feed) and a lot of other garden plants that provide lots of extra material to mix in with the vegetable material. A bit of fresh manure can also accelerate the composting process. Urine is another accelerator, though I would not recommend this if you are on a lot of medication!
The heat that can kill seeds, roots and diseased material comes from the micro organisms as they digest the composting material. However, allotment compost rarely reaches an even, high enough temperature, so I strongly advice to dispose of these off site or as a last resort dry and burn them. You can tell if you have had a good mix in your pile and heat has been generated as the pile has suddenly shrunk in height from one allotment visit to the next.
Green and brown material ratio:
There is a lot of advice regarding getting the mix right of green and brown materials, but as long as you add a bit of both, the ratio does not matter. It is something that you learn with experience too. For instance if you add a thick layer of grass clippings, they are likely to go soggy, smelly and do not break down very well. But if you layer them with other materials you are onto a winner.
Green or nitrogen materials:
Vegetable trimmings (not too much onion/leek, scares worms with smell)
Green leaves
Grass clippings
Kelp or seaweed
Green shrub prunings
Tea bags and coffee grounds including filter
Herbivore animal manure
House plants
Weeds without seeds and tap roots
Old flower bouquets
Brown or Carbon materials:
Straw
Brown cardboard (not glossy and no tape or glue)
Dry shredded leaves
Sawdust
Newspaper scrunched up into balls or shredded paper
Wood ash, not coal
Dried grass
Egg cartons, toilet roll holders (I avoid these)
If you only have a lot of green material to compost, then add a sprinkling of soil every so often to prevent the pile going soggy, and make sure there is a good airflow.
If you have a lot of brown material, bag it up and wait till you have green to mix it with, or add soil as above. Brown stuff takes a lot longer to break down if not mixed with green material.
I use a lot of brown cardboard ripped into smaller pieces. I have a huge palm tree at home so have lots of brown long leaves. I cut them into 1-2 inch pieces and add them to the compost. Because I add quite a lot of dry stuff, I do water my pile now and again if we do not get any rain. I do not really cover my piles in the winter, except for the top to prevent them getting too wet. I use wood and I do not recommend using carpets on allotment sites as they are full of plastic fibres and you will be getting that in your soil.
List of materials to avoid at all cost:
Invasive plants (Ivy, bramble, bind weed)
Meat
Dairy
Fish
Bones
Oil/fats
Diseased plants (blight, club root etc)
Chemicals
Glossy paper
Rice, walnut shells
Treated wood
Animal waste
Good luck composting!
