The National Allotment Society - National Society of Allotment and Leisure Gardeners Ltd

Composting

Why make Compost? Your plot will inevitably generate green waste, from weeds to old crops and spent compost, but please do not be tempted to dispose of it at your local tip. This “waste” is actually a tremendous resource, as a large percentage of it can be recycled into compost that will enhance the fertility of your allotment garden. Your “black gold” will

  • Improve soil texture
  • Improve aeration of the soil
  • Increase water–holding capacity of the soil
  • Improve soil fertility
  • Feed micro- organisms that keep soil healthy
  • Reduce landfill pressure
  • Save you money

How to Compost using the "Cool" Method Compost production works best when there are a couple of heaps on the go at the same time; one that you are adding to and another that you have filled and left to decompose; a process that can take up to a year. The containers could be wooden bins (with a cover) or plastic composters, whatever suits your space. The volume of your container should be ideally be 1 cubic metre, any less will still work but may take longer. If there is a vermin problem on the site it is wise to put metal mesh at the bottom of the heap, over the bare earth.

To create good compost, you should mix carbon-based waste (browns) half and half by volume with the nitrogen- based plant (greens) remains. The green material provides nutrients and moisture whilst the browns decompose more slowly and provide the energy source for the microbes that carry out the composting process. The brown material also absorbs excess moisture and facilitates air-flow within the heap

Browns (carbon) dead leaves, old straw/hay, dry plant stems, sawdust in small amounts, shredded paper in moderation, wood ash, torn cardboard – small pieces.

Greens (nitrogen) grass – in moderation, fruit and vegetables (raw), tea leaves and coffee grounds, pea and bean-tops, manure, bedding plants, urine – male only, young weeds, flowers, comfrey / nettles.

Cut or bruised comfrey leaves layered through your heap will encourage bacterial activity and speed up decomposition. Woody material should be chopped up or crushed, shredding will speed up the process but is not necessary. Turning the heap now and again or mixing with a fork or compost aerator will introduce oxygen and help the materials to break down. There is a slight risk of inhaling harmful spores whilst aerating so make sure the heap is damp and if you have health problems wear a mask. You may need to water in dry spells. Most plot-holders follow this cool composting regime; hot composting takes much less time to produce compost but is more labour intensive.

Not to be included cooked food or bread, meat or fish, coal and coke ash, cat litter or dog faeces, glossy magazines, plastics, metal and glass.

More details of a low effort hot compost technique suitable for an allotment and information on other forms of composting can be found at www.carryoncomposting.com

What to do with weeds All weed tops apart from bindweed, ground elder or those with seeds can be added to the compost heap; send those to your council green waste service. Some councils will offer a green waste collection service to allotment sites. Other roots can be rotted down in a bucket of water for a few weeks and then added to the heap. The liquid can be diluted and used as a plant feed. Roots can also be crushed and then baked in the sun on a metal sheet or inside a black bag to desiccate.

What to do with diseased material Plant materials infected with club root or sclerotina (onion white rot etc) should be disposed of offsite, temperatures at the council green waste facilities will get high enough to kill these pathogens, your cool compost heap will not. Powdery mildew and rust are less persistent and if the disease has been caught early, material could be added to the heap, otherwise dispose of at your council facilities. Fruit suffering from brown rot can be buried at least 30cm deep, burn or dispose of infected wood.

Can I take materials to the plot to compost? Check the allotment site rules to see if it is permitted to bring green garden waste or vegetable and fruit peelings from your kitchen to the site; some authorities permit this, many do not.

Leafmould Store collected leaves in wire containers or sealed black plastic bags, add some grass clippings or coffee grounds for nitrogen and ensure they remain damp. Ideally, they should be collected with a mower on a high cut to shred them. Store the leaves for at least twelve months to allow them to break down sufficiently. The main benefits of leaf-mould are that it contains twice as many minerals as manure and retains 3-5 times its weight in water, making it an excellent choice for improving your soil structure. Leaf mould makes an excellent mulch and is a key ingredient when making homemade potting and seed composts.

What to do with your compost Well -rotted compost can be dug in to your plot at any time (depending on soil type) other than summer - when the warm soil will break down the nutrients to be washed out by winter rains.  If you follow a no-dig regime the compost can be used as a mulch in late winter or early spring, this will help to conserve soil moisture and inhibit weed growth.  The compost can also be used as an ingredient in home- made seed and potting compost.

Compost Awareness Week aims to raise the awareness of the public regarding the benefits of using compost to improve or maintain high quality soil, to grow healthy plants, reduce the use of fertilizer and pesticides, improve water quality and protect the environment. It is held each year at the beginning of May.

A 2014 Report from Dr Jill Edmondson at Sheffield University found that 95% of plot-holders in their study composted their allotment waste, recycling nutrients and carbon back to their soil effectively. As a result of this practice the survey found that the allotment soil was significantly healthier than surrounding arable fields. Allotment soil had 32% more organic carbon, 36% higher carbon to nitrogen ratios, 25% higher nitrogen, and was significantly less compacted. So, plot-holders - keep on composting!