A new look at composts

Composting is one of the fundamental pillars of gardening.

You must have a compost bin. If there were gardening laws then you would be obliged by those laws to have, use and maintain a composting facility if you have any sort of garden. Balcony, compost bin. Roof garden, compost bin. Pot of bedding plants by your back door, compost bin. Penalties for not owning and using a compost bin would be high…

Mercifully there are no laws specifically relating to the ownership and use of a compost bin. But surely as a committed gardener and general fan of keeping the planet going I should be rather keen on everyone composting? The answer to that is yes and no.

Let me ask you a question: have you ever seen a Victorian compost bin? Think about all the old gardens you’ve been to; have you ever seen a brick bay for compost or some contraption for making compost? The 19th century was a great time of ingenuity in the western world, and gardening was no exception. We had cleverly designed greenhouses for different exotic fruits, often heated using ingenious heating systems (think ‘stove house’), we had tools for every little gardening problem, and we saw the rise of books and magazines to disseminate knowledge. It was a boon time for gardening, so where were the compost heaps supplying much needed compost for these gardens?

There weren’t any.

The realisation that the explosion of Victorian gardening wasn’t done with barrows loaded with fine quality compost comes as a surprise to most gardeners; it came as a surprise to me too! Composting is something deemed so integral to conventional gardening that the idea of its absence is astonishing.

Gardening wasn’t without organic matter, however, it came from a different source. At a time when horses were the principle means of local travel there was absolutely no shortage of… by-products. Stable yards were everywhere and consequently few gardeners were far from a dung heap. You could for many decades order a cart-load of manure from nearby stables and have it delivered to your garden, ready to use. In some cases you had to let the manure settle and mature before using it, while in other cases it was more ready to use.

The introduction and increased use of other modes of transport (steam lorries for goods, electric trams, the expansion of the railways that ended the era of the stagecoach, the introduction of the combustion engine etc), in some way caused by or at least sped up by the loss of so many horses during the first World War, brought a decline in the availability of horse dung.

Now the obvious question here is “what about potted plants?” It’s a fair question. Of marginally less surprise to modern gardeners than the lack of compost heaps is the relative lack of pots. Plant pots were very much in existence during the 19th and early 20th centuries but were very expensive. Thus they weren’t in widespread use, remaining the preserve of the wealthy and/or specialists up to the middle third of the 20th century. Pots were reserved for the most precious plants; even in the gardens of the wealthy most plants were sown in wooden trays or cold frames and then planted out, or were direct sown where they were wanted (under cloches where available). Growing plants in pots was usually reserved for indoor cultivation.

For most plants the best growing medium was based on loam, a topsoil specifically made by stacking upside-down pieces of turf and allowing the grass to break down naturally. Properly done the resulting material makes a friable soil suitable for planting, although not necessarily without added material.

“Now is the time to secure a good supply of loam to stack in preparation for potting fruit trees and making borders. Is the presence of wireworms is suspected, a liberal dusting of soot should be given, and fertilisers added in layers. Old lime-rubble and burnt earth, too, may be added to heavy loams, while marl* and old cow manure will be beneficial to light, sandy soils. Good liquid manure may be liberally applied to heavy or light loams with excellent effect, and after pot trees have been cleared of their fruit and require a shift, the sooner they are repotted the better. The compost treated as above may be chopped down as required and exposed to the sun and air until it is dry and warm.”

F. Jordan, V.M.H., Gardener to Colonel Spender Clay, Ford Manor, Lingfield, Surrey. Taken from The Gardeners Chronicle, 6th of June 1931.
(*broadly speaking, marl is a lime-rich clay)

This compost is much more refined than simply using soil in pots, showing that at this time a great deal was known about the importance of structure in growing medium. It also bears stark contrast to the read-made potting composts available today; here the gardener must acquire a series of ingredients, assess the structure of the loam and make a judgement of what should be added to create the desired consistency.

Replacing the enormous amounts of organic matter needed was already causing great concern to gardeners, and at the beginning of the 1930s a new idea of creating artificial ‘humus’ was filtering through from India. The idea is startlingly similar to that of modern composting; make layers of different ingredients, allow them to break down and then use the end product in place of animal manures. I’ve not yet tracked down that original Indian recipe, but the method was being increasingly experimented with during the 1930s, rather notably in South Shields where a new public park was being made from a flattened ballast hill (a pile of discarded stone that had been used as ship ballast). The creation of South Shields Bents Park needed enormous amounts of organic matter to balance the stone layer, and 90% of the organic matter came from the compost heap. Each year 200-300 tons of organic matter was created.

You’re going to want to hold your nose for this one….

“Stable and farm manure was scarce so all rubbish such as leaves , the tops from herbaceous and annual plants, were carted into a large yard and thrown against a wall some twelve feet [4m] high and sixty feet [18m] long, with the ground sloping down to one point where a well was dug to catch all drainage. After the first few loads were in position a sloping front was obtained and as other rubbish was thrown up it mixed as it rolled down. Waste from the slaughter house came in once or twice a week and was spread over the front of the heap to be covered over either with lawn mowings or road sweepings brought in by corporation carts. When playing fields etc. were scythed the grass so cut was also mixed in; waste hops from local breweries were brought in twice a week and immediately covered with road sweepings.

In early autumn the whole heap was turned away from the wall, and if any particular substance was found in bulk it was mixed properly with the rest. By this means the wall was cleared to start a new heap, and when the material was carted out it was always loaded from the side of the heap nearest the wall. By this method the oldest material was used first and the ground cleared for the developing of the new heap.

The bulk of this ‘manure’ was used during the winter months for borders, shrubberies and plantations etc; the rest was used for mulching and or in connection with any replanting which took place over summer. Clay was also brought in by contractors, spread over the land and dug in; this gave the gravel the necessary holding powers.”

A.L.S, South Shields. Taken from The Gardener’s Chronicle, January the 18th 1936.

This account of the composting at Bents Park was corrected a few months later by the incumbent Park Superintendent. As there is relevance to both accounts I have included both the original account and its correction.

“…so I offer a brief outline of the method of making these manure heaps, a method my predecessor carried out for upwards of thirty years, and which, so long as material is available, I intend to maintain.

Stable manure is becoming daily a very scarce commodity, but with a few loads weekly it is amazing what an amount of good compost can be created by the help of other ingredients. Your correspondent states that we use the old tops from herbaceous plants. We do not use these in the compost heap, but trench them down when they are removed from the borders. We use leaves, grass, both lawn-mowings and long, playing field stuff, annual weeds, street sweepings, slaughter house refuse, wood chippings, (of which a goodly supply is used for bedding horses), spent hops from breweries and, in fact, anything we can procure that will decay.

We have no soakage pit, the ground being fairly level or, if anything, sloping to the wall. As the material is carted into the the yard it is thoroughly mixed into a conical heap. As the heap enlarges fermentation begins, and to preserve the heat and also prevent obnoxious smells, a thin layer of sand or soil is scattered on the mound. When the heap has had time to get well heated through it is again turned , back to the wall, where the process of fermentation continues. This gives room to again commence another conical heap. Before turning to the wall our heap will consist of several hundred loads of material. This process is carried on the whole year round, and by the time the season for carting out comes round our yards are filled to capacity with a very valuable fertiliser.”

R. Astley, Superintendent, Marine Parks, South Shields. Taken from The Gardener’s Chronicle, March the 21st 1936.

You’d hope, really hope, that the waste from the slaughter house was manure. As it’s mentioned separately from manure I have a horrible feeling it wasn’t….

Note here that R. Astley mentions that his predecessor had been making these heaps for over 30 years, which rather suggests that this form of composting, and I use the word somewhat loosely here, had predated the introduction of the method from India. I suspect that the crucial elements of the Indian method, such as I have found account of it in my resources, was the use of plant material and the careful attention to layering.

It’s interesting to note that this was the time when the John Innes Institute began to promote a new standardised compost recipe for optimum results. The recipes, based on many years of careful experimentation, were based on loam, peat, sand and various nutritional additives in differing quantities according to what the compost was to be used for (seed sowing, potting on, potting up mature plants). This was a revolution in some ways, a tried and tested standardised recipe that every gardener could use for optimum results. The only flaw with this was the fact that the consistency of loam varies according to local soil type, but despite this the ‘John Innes’ recipe became the benchmark for potting composts, even surviving the move from ‘home made’ to bagged composts a few decades later. While modern ‘John Innes’ composts have varied the ingredients (not least of all swapping loam for soil), ‘John Innes’ is still the name used for any heavy soil-based compost even now.

Going back further into the 19th century it’s interesting to see that Mrs Beeton (the Beeton of ‘The Book Of Household Management’ fame) discusses the relative benefits of different manures and goes on to tell of the importance of ‘liquid manures’; in the farm/stable this would be the urine drained from enclosures. In Mrs Beeton’s ‘Garden Management’ there’s a method of making your own liquid manure which essentially advocates dumping manures (including that of chickens when available), vegetable waste and “animal refuse” (which I take to mean raw or cooked meat, giblets etc) over a mesh, flushing it with water from household tasks (washing etc), and collecting the resultant liquid in a pit and using that as a liquid manure. While Beeton does discuss the use of animal manure on soil it’s clear that she considered these liquid manures superior. She then went on to discuss other materials, such as leaf mould, as useful organic matter.

It’s clear that the 1920s and 1930s were problematic for those reliant on manure in horticulture. It’s perhaps surprising then that composting wasn’t becoming more widespread. One reason that this wasn’t such a big issue was down to a profound change the came about after the first World War.

After the first World War there was a mass exodus from Britain’s farms, as those who had laboured on farms chose to move to towns and take up other forms of employment. Mechanisation broadly kept up food production but with more predictable income and free time the more prosperous urban gardeners were less interested in growing fruit and vegetables and more interested in ornamental plants. Not everyone of course was lucky enough to have a garden; poorer families ended up in terraced houses with only a yard, if they were lucky enough to have any outside space at all.

The declaration of war in 1939 caused enormous problems for Britain’s food supply. By the late 1930s Britain was importing around 750,000 tons of fresh fruit, vegetables and meat from Europe alone, so to suddenly lose access to that food was a major issue. After an initial period of panic buying rationing was introduced, along with a bold campaign; Dig For Victory.

The idea of Dig For Victory was fairly sensible; anyone who had any area of land would turn that land over for food production, either to supplement their own rations or, in the case of larger gardens, to supply food to others. There’s not much evidence that Dig For Victory was exactly an overwhelming success; not everyone had good growing conditions for vegetables (too shady, too wet etc), but the campaign was as much about giving people something to do in the absence of their usual activities as it was about producing food. The food coming from America on the North Atlantic Convoys was the crucial key to keeping Britain fed.

Even before ‘Dig For Victory’ as a campaign was publicised there were discussions about how to increase yields in gardens. It was plain that fuel would be needed for the war effort, and this, coupled with the dramatic reduction in Britain’s population of horses, meant that delivering useful amounts of manure to gardeners was not going to be possible. Home composting was suddenly thrown into the spotlight, and gardeners were encouraged to recycle as much organic matter as possible in their own gardens; to essentially make their own manure. When you picture the wartime garden you think of it full of vegetables, but at least initially gardeners were advised to keep an area of lawn… lawn clippings can go on your compost heap!

Regardless of the success, perceived or otherwise, of the Dig For Victory campaign composting was ingrained in our gardening psyche. The idea that we should all make our own compost is being pushed even more now with climate change very much of concern, but composting has never really gone away as an idea, perhaps surprising given the introduction of bagged ‘multipurpose’ composts.

‘Multipurpose’ compost was a revolution for gardeners. The idea that the same bag would give you a compost to mulch or dig into your soil and sow seeds and pot plants up with was the stuff of dreams. No more mixing loam and other ingredients, everything you and your garden needs in one easy to buy bag. Peat harvesting, formerly a niche activity, became big business as peat was a reliable and fairly easy to acquire base material. Manufacturers could drain the water from peat bogs, scrape the peat out of the ground, mash it up to make it nice and fine, bag it up with a little feed or extras added, and sell it to gardeners. Coupled with ever cheaper and reliable sources of pots, the whole world of modern gardening was born. You want to sow some seeds? Get some seed trays and a bag of compost. You want a houseplant? Buy a plant, a nice pot, and a bag of compost. Got space but no soil? Easy, just get some nice big pots, a load of plants and some bags of compost, and make yourself a whole garden in containers!

The rise of multipurpose has been probably the single most influential thing to happen to modern gardening. It’s opened up a whole world of convenient gardening to us all, but as we’re learning with a lot of convenient modern things there’s a price to pay.

Peat is not just extracted for horticulture. More peat habitats are destroyed by development and draining for agriculture than horticulture could ever use. Peat is also still, at the time of writing, extracted as fuel in some areas. Horticulture’s contribution is, while really quite small, still a contribution.

Not all peat habitats are equal. Not all are wonderful habitats teeming with a diverse range of species. Many peat habitats are permanently frozen and largely barren, as can be seen in some parts of Northern Europe and Siberia, while others are rich with an extraordinary range of plants and animals that have adapted to cope, and thrive, in challenging conditions. Peat bogs are all carbon sinks; plants take in carbon dioxide and store it in their tissues, but while in most places the breaking down of the plant tissues releases that carbon back into the atmosphere the anaerobic environment of peat bogs keeps that carbon trapped in those plant tissues. Peat is essentially made up of organic fossils in various states of preservation. This might be a simplistic view, but broadly speaking….

As the gardening world starts to recognise the impact of some of its activities on the natural world there’s a desire to change things for the better. This is of course admirable, but not without issues.

I believe strongly that many of the things currently advocated as part of our move towards sustainability will prove to be insufficient or fundamentally flawed.

As I said above, the multipurpose compost is a wonder of modern horticulture. However where do we go from here if we don’t rely on peat as a base ingredient for composts? There are many peat-free composts on the market, a few of which prove to be excellent, some are perfectly adequate with certain conditions, while others are pretty terrible. The finest peat-free compost I’ve come across is the Sylvagrow product by Melcourt; it’s uniform and it has a good structure. Dalefoot make a fairly good product based on composted wool which is similarly uniform, but the structure can be a little too moisture retentive in wetter regions so additional drainage material would be required. Two of the best and I’m already adding something to make the compost suitable for certain conditions… the question is whether the large number of amateur gardeners would be able to open a bag of compost and make a judgement over whether or not a compost needs extra ingredients added? My guess is no at this moment of time; when composts were something you made from ingredients the skills needed to judge the quality of those ingredients were more common.

And while we’re mixing ingredients let’s also remember that prior to the introduction of multipurpose composts different ingredients were used for different things. For soil improvement horse manure was considered best, while for potting plants a loam-based compost was made up of several ingredients. Different composts for different purposes. There are soil improvement composts marketed today, along with farmyard manure and composted bark which are also recommended, but to the majority of gardeners compost is compost, regardless of specific uses. I would hazard a guess that the majority of bagged composts currently sold ends up in some sort of container, which brings its own problems.

Container cultivation is ingrained in modern gardening. Vegetables and flowers are sown in seed trays, cell trays or small pots and then often potted up individually before going out into the garden. In the garden itself larger pots hold treasured or feature plants on a permanent or short term basis. Magazine editors would be lost without the obligatory ‘seasonal container display’ feature each month, and of course for some people (until recently including myself) pots are the only way you can grow anything if you don’t have a garden. I’m not even remotely convinced that the majority of domestic compost consumption goes on permanent or semi-permanent container cultivation by those who have no other choice; I suspect that most compost is used in gardens with useable soil.

Even taking into account the bad peat-free compost, there’s no way, realistically, that compost producers can replace the annual peat-based compost supply with peat-free compost. It’s not a lack of will but a lack of raw materials and capacity. No matter how much they expand and source new materials it’s simply not feasible to expect producers of peat-free composts to match current demand.

The obvious answer is to make your own compost, but here we hit another snag. Compost ‘wisdom’, using kitchen peelings, grass clippings (but not too much!), a layer of twiggy material or, for some reason, cardboard… that’s the recipe for the manure replacement compost used in the 1930s and onwards! It’s not potting compost! The closest to a peat-free, or at least non-peat-based, potting compost is a John Innes mix, but while it’s entirely possible to make your own at home who has access to loam? Even loam-based composts use topsoil instead of loam now….

There needs to be a revisiting of compost advice, bringing the advice into the 21st century. If people want to use composts in the same way they do now then it’s vital that we, gardening experts, experiment with alternative compost making techniques that will give gardeners the light, porous compost needed for container cultivation, rather than trying to persuade gardeners that the claggy, heavy compost that comes out of their compost bins is exactly the same as the multipurpose they’ve been using before. Greenwaste composts are a nightmare in pots, as I discovered in my previous line when the nursery I worked for moved from Melcourt’s good compost over to a greenwaste product (the compost was terrible and we lost 60-75% of stock, and believe me when I say that a compost has to be bad for Berberis darwinii to fail!). We need to give gardeners new, updated, relevant information rather than blindly following composting advice from nearly a century ago.

When I’ve spoken to clients about composting kitchen waste I’ve asked them a question: when they put their hand into a bag of potatoes and find that one has gone bad, how often do they bring out a nice pile of crumbly compost? The answer is never. Fruit and vegetables rot in compost, granted adding a certain level of ‘bulk’ but still hardly making a nice growing medium for plants. Perfect for adding organic matter to soil, but creating problems for plant roots in containers.

If access to good composts is going to become more challenging then gardeners will have to reduce their consumption massively. This won’t be a terrible thing, environmentally speaking; extensive pot cultivation is more destructive to the environment than growing in soil, with pots needing to be manufactured and transported, compost needing to come from somewhere, and additional watering and feeding needed through the growing season. However pots are also very useful, especially to those who grow edibles from seed every year. How do they cope without a reliable source of cheap compost?

The answer to that is that we look back to how things were done before we had cheap pots and composts, albeit with modern understanding. Cold frames and cloches would be a really good place to start, encouraging direct sowing wherever possible and then the lifting of plants into their final spaces if and when necessary. Soil warming cables were in use in 1936 so are hardly a new invention, but maybe these have a use again in the future? Using modern materials and understanding it must be possible to improve on the practices of times gone by?

Already the practice of manuring ornamental plantings is fading out, especially with the modern ‘New Naturalistic’ style of gardening where plants are chosen according to their suitability to the site, rather than the gardener changing the site to boost the plant. In my own experience herbaceous borders on good soil do very well without masses of extra nutrient added as mulch. If anything over-fed borders cause problems, with plants growing tall and thin, becoming susceptible to wind damage and needing support. Drop the nutrients and the plants grow perfectly well, flower well and become more resilient.

A few years ago I decided to experiment a little with fallen leaves. Rather than take the leaves off lawns and paths I started to gather them up before either running over them with the lawn mower or ‘whisking’ them with the strimmer. Also rather than take thin herbaceous plant stems away in late winter I cut them backwards and forwards with a hedge trimmer. In both cases I spread the material on the soil surface to break down naturally, only removing excess material where required.

The result of this has been startling, and I now do this in other gardens too. Firstly the leaf litter has provided a habitat for insects… a lot of insects. Working in the border the number of beetles and ladybirds I found in the leaf litter was astonishing. Beetles are of course important foods for hedgehogs, and in a couple of gardens hedgehogs have made themselves at home. There’s been a noticeable effect on plant health too, with plants shorter and stouter than before but every bit as floriferous. Taking away organic matter and bringing it back a year or so later as compost is in some ways beneficial to the plants themselves, even if it does cause excessive growth, but by feeding the soil organisms, bacteria, fungi, insects and worms the soil has become healthier and that has translated into happier plants. Yes, the reason why your soil doesn’t have many worms even though you mulch every year is simple; worms eat leaves, not compost!

I’m not suggesting that my methods will work everywhere but I will say that the constant peddling of tired old methods because they’re ‘received wisdom’ isn’t going to help anyone. As you’ve read above, the way we manage and feed our plants has changed quite a bit over the years as understanding has changed. It’s clear that the next decade or so will be challenging for gardeners, and what’s needed is a reevaluation of the current advise on composting and a new strategy built up, one that reflects the real and current needs of modern gardeners.