How to (Gardening) is intended as a useful resource to clients of Garden Displays Ltd or anyone looking for a brief but comprehensive and helpful insight of specific garden topics. Subject matter is influenced by areas of interest identified by client FAQ's. As topics arise this resource  will continue to grow.  

How to make a garden compost heap

by John Gordon - 20:31 on 19 December 2018

The perception of a beautiful garden means different things to different people. Some like neat and tidy order, others a more unkempt natural look. The latter like natural habitats tends to be more self-replenishing in terms of returning nutrients to the soil via decomposition of organic matter and in turn improving the overall condition of the soil for the plants occupying that particular habitat.   Over the years removal of organic matter in the form of grass clippings, fallen leaves, weeds and pruning’s etc. to keep the garden neat and tidy results in a gradual  ongoing decline of nutrients. To keep garden plants healthy and looking their best feeding and improving the structure of the soil is necessary. 

Fertilisers and soil conditioners to improve the soil can be purchased  and applied but on reflection  seems a little silly when one considers that the raw materials for these products exist in the garden often being removed to council recycling sites.

 After passing green waste through a shredder the council recycling sites operatives pile up the garden waste into long heaps, called windrows. After several months of turning those windrows produce compost which is available to the public and business which often bag the stuff for resale in garden centres etc. The compost making process is strictly monitored to ensure the end product meets approved standards.

 However being a frequent user of such sites to dispose of client’s garden waste I am aware of the large number of contractors using such sites and the volume of unwanted materials being deposited such as perennial weed roots and seeds and other contaminated materials such as diseased plants and grass mowing which have been treated with lawn weed-killer.  Although the high temperature reached in these windrows should kill off most pathogens and regenerative weed roots I am not convinced of how fool proof the process is. I have witnessed the introduction of weeds species not originally present in a garden after application of such compost. There is no better, safer and satisfying compost than your own good stuff.

 A compost heap is an integral component of a garden just as an engine is an integral component of a car.   There are a number of reasons compost heaps are often omitted from gardens; they look untidy, are too much work or for many, compost making does not work for them.

How many compost bins and where to place them?

The size or number of compost heaps is governed by the size of the garden, the number of planted areas and volume of plants contained within them.  A compost heap does not have to be started in a purpose built structure such as a compost bin (which will almost certainly not be big enough necessitating the need for several such bins in the average garden) it can be started simply by piling up garden waste in a suitable part of the garden and covering with polythene, old carpet, old bed sheets etc.

Compost heaps can be situated in any less utilised and unobtrusive part of the garden. I often read that they should not be placed in full sun but I think most people would prefer to use such a spot for their prized plants or a seating area to enjoy the warmth.  They should not be placed on “tidy” solid bases such as slabs, contact with the soil is essential to allow the migration of micro- organisms to aid the decomposition process and rain water to seep away. Room to get to the compost and turn the heap when desired should be included and a nearby water point to wet the heap easily if too dry is preferable, although admittedly not normally essential in Scotland.

Three common mistakes to avoid

The three most common mistakes on placing garden waste on the compost heap are adding perennial weeds, large branches and too much of the same stuff. Avoiding these three mistakes will ensure easy and successful composting.  

Obvious Perennials weeds such as those with fleshy or creeping rather than fibrous roots or those which are observed over years to self- seed too freely, will, if added to the compost heap, eventually be returned to the garden soil. When weeding it is always best to have two containers; one for material to be placed on the garden compost heap, the other for the garden bin (and council landfill site).

Mixing large branches into compost heaps is a mistake as they take a long time to decompose, making the heap difficult to turn and access the compost at the bottom. Large branches are best cut into as small pieces as possible (ideally bout 4cm or 1.5 inches) or passed through a garden shredder.

Too much of the same stuff, normally grass clippings, is the third culprit to getting composting wrong. Compost heaps are best built up in alternating layers of different materials.  This is a straight forward process as individual shrubs are best pruned after they have finished flowering, as are early flowering herbaceous perennials. These together with weeds can be alternated with grass clippings, fallen leaves etc. Large volumes of grass can be spread at the back of shrub borders directly where it is less noticeable and forms effective weed free mulch.

If the garden has or is overlooked by lots of trees then after leaf fall in the autumn, the leaves are best kept in a separate heap to produce leaf mould and after two to four years depending on the speed of decomposition placed as mulch around shrubs and herbaceous perennial in borders.  Leaves do not need to be turned or have activators added  as they do not heat up enough but the heap should be kept moist  to encourage fungal growth which rots down the leaves.

Think carbon and nitrogen  

The most abundant elements contained in garden waste are carbon and nitrogen. Grass clippings, weeds, bedding plants which have passed and foliage of cut back herbaceous perennials as well as kitchen scraps (although not cooked food which attracts vermin) have a good equal balance of carbon and nitrogen.  Shrub pruning’s and fallen leaves tend to be have a higher percentage of carbon than nitrogen whilst high levels of nitrogen can be obtained from poultry manure, seaweed, bone meal, and dried blood. I do not use bone meal or dried blood round my garden as I have found my dog digging up any area which I have applied it to.




What are activators?

 Activators speed the decomposition process. Although they can be bought any well balanced green waste or product high in nitrogen (re-read previous paragraph) are high in nitrogen, including human urine, so there is no need to purchase proprietary activators.

Following these principles will result in successful composting.  Turning the compost heap is a heavy chore made even more difficult if space is confined. It is not essential but does speed the process allowing oxygen for aerobic micro-organisms to increase and in turn speed decomposition. Paying attention to building the layers carefully and space to work the heap makes the ‘chore’ of turning the heap not only many times easier but dare I say enjoyable and satisfying. Getting nearer the bottom to the crumbly rich odourless compost and seeing that the composting process is working, can make one look forward to the next turning time. Well it does for me.

Where to use compost?

 Depending on how well your garden waste is composted it can be used for potting up plants and even sowing seed. However, most of my compost is applied over my herbaceous and mixed borders in the spring. When I see the first bulbs emerge and I know they will soon put on a spurt of growth before flowering.  I cut down to ground level all  vegetation which has remained over the winter months  for winter structure and  preventing frost from penetrating the ground too deep and perhaps damaging tender plant crowns  as well as a habitat for wildlife. The cut back debris I place temporarily into bulk bags. Once I have removed the good stuff from lower down the compost heap, the bags will be emptied into my compost heap to make next year’s compost. After I have removed the largest overwintering weeds and split any herbaceous plants that are outgrowing their positions I spread my lovely compost over the ground as surface mulch.

The compost will continue to protect the soil from frost and over the years gradually and continually improve the structure of the soil.  I like to maximise the growing potential of my ornamental plants by adding a sprinkling of Growmore fertiliser throughout early and late summer at four weekly intervals. Spring however is too early for me to apply such fertiliser in case a late frost damages a surge of soft new growth stimulated by a shot of concentrated fertiliser.

Making your own compost is immensely satisfying as is looking at stunningly beautiful, lush and colourful borders. As the years pass, your soil, even if initially it contains too much clay or sand, becomes an easy to work friable soil, like a vegetable plot where your plants will thrive.

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