The sustainability thing…

‘Sustainability’ is very much the ‘in-thing’ at the moment. Horticultural media is full of it, and it’s a topic that is hotly discussed in gardening circles. So what is it?

Nobody seems to know.

Or at least nobody seems to have a clear, defined answer.

When you ask “what is sustainability” you get a series of words and ideas in response. “Wildflowers”, OK wildflowers are sustainability. “Water butts” are also sustainability. “Heritage seeds” seem to be sustainability too. “Growing your own” sooner or later appears in the list of concepts… don’t forget ‘pollinators’!

The respondent seems very happy with themselves, yet the question a remains unanswered.

Rather than wade in to the rather broad topic of sustainability I would like to look at a few of the things you meet when you talk about sustainability in gardening.

Water Butts

Water storage is a very popular idea in sustainability. As weather becomes drier there will be more and more pressure on our supply of clean water, so as gardeners it’s vital that we store as much water as we possibly can. Or is it?

Firstly there’s the issue of whether a warmer climate will bring drier conditions. Discussions about extremes in climate tend to look at dry regions becoming drier, but less is made of regions that already receive larger amounts of water getting even wetter. Of course it’s not this clear-cut, as changing weather patterns will likely mean that reliable weather events, such as the monsoons of Asia, become less reliable. We’ve already seen the effects of monsoons not arriving in countries like Bangladesh. Broadly in Europe we’re expecting the areas of higher rainfall to become wetter, so realistically plants in these areas are going to need to learn how to swim, and the need for supplemental water will be very low. We’re likely to see too much water in some areas and not enough water in others.

So this means that water butts will be really vital in areas that experience drier conditions? Well here we come to the major fundamental, and seldom discussed, flaw with water butts; once they’re empty they’re absolutely useless until the next significant rainfall. Let’s do some sums:

If you have a standard 120 litre water butt (US readers stick with me here) that means that you have have the capacity to store 120l of water coming from your roof. Brilliant. Let’s say that it rains really hard on Monday morning and fills the water butt right up…

You’re probably not going to need to water your [outdoor] plants on Monday or Tuesday, but by Wednesday morning your plants need watering, so you take your trusty 10l watering can and water your plants, using 60l of water to soak your pots and the newly planted plants in the ground. It’s hot and dry on Thursday too, so you water all your plants again… and now you’ve used 120l of water and emptied your water butt. What happens to all your plants now if it doesn’t rain?

Now I’m not saying that the 120l of water you’ve stored isn’t of use; it’s 120l that you’re not taking out of the tap, and during a water shortage that is really important. What I am saying is that water storage relies on there being times when the used water is replaced, and if those times become infrequent you might easily find your water storage useless.


The idea of growing wildflowers in the garden has virtually nothing to do with any sort of sustainability. Natural habitats are under threat all over the world and too many plant species are being marginalised in favour of human development. This is undoubtedly a bad thing, so the answer is to bring the wild plants into the garden.

Firstly I must admit to a loose and casual belief that the boon in wildflowers in horticulture is part of a conspiracy to allow the increased destruction of our wild environments. It’s not exactly my dearest belief, but think about it this way; while gardeners believe that letting their lawns grow long each May for ‘no mow May’ actually makes a difference they seem blind to the destruction of natural habitats all around them. There’s a temptation to believe that because a species is growing in your lawn or in the cracks in your pavement that you are making a big difference. You’re not. No amount of gardening-goodwill towards native plants in the garden will ever make up for the destruction of pristine habitats. How anyone could think that a patch of ‘never winding wingle-wangle’ or a lawn full of ‘kiss me by moonlight in my favourite hat’ could ever compensate for the loss of intricate and ancient pristine habitat is beyond belief, and worst of all while the gardener is patting themselves on the back for their important efforts to sustain populations of wild plants they’re not getting angry about the wholesale destruction of our precious wild spaces.

I’m not for a moment suggesting that wild plants shouldn’t have places in our gardens. If you find the green flowers of ‘can of lager on the way to work’ works well with your Geraniums then grow it, and if the nodding flowers of ‘illicit affair with the milkman’ are a charming detail under a shrub then fine. Providing their cultural needs are met, and providing species are chosen with an eye towards potential future nuisance, there is no conceivable reason why native plants shouldn’t be grown in the garden. Just don’t lose sight of the plight of plants in the wild.

You may have enough room to have a wildflower meadow, and how nice for you. Wildflower meadows on a small scale are largely pointless, providing insufficient food for insects during the surprisingly short period of peak flowering. Think of it this way; a garden with the usual plants growing in it is like a supermarket; food varies in quality and in its health benefits but is generally predictable and reliable. By comparison a wildflower meadow is like a giant food fair, full of wonderful nutritious food but only for a certain time, so while it’s possible to gorge yourself and store some food for lean times it’s not necessarily practical to rely on it. This is a blunt analogy but broadly suggests my point; helping pollinators is about more than just providing a giant meal in summer.

Please don’t go looking up the wildflower names above…


I admire the naivety of people who think that gardening can still be done ‘the old way’. These people haven’t realised that it’s not 1930 any more; modern life brings enormous pressures on time and labour is realistically too expensive to bring in a gardener and get them to do things without powered tools. If you want a gardener to trim your hedge with shears then it will cost you… time is money!

Machinery certainly helps make life easier, but comes with a responsibility. Petrol machinery is generally frowned upon as it’s gives out pollution (although weirdly the same people who complain about petrol consumption will happily jump into their car to go on a not-exactly-necessary pleasure trip), and battery tools aren’t up to the rigours of heavy usage. For smaller gardens battery tools are absolutely the way to go; 20 minutes battery life on a tool you only use for 10 minutes means no issues of ‘running out of juice’, while 20 minutes battery life on a tool you use for several hours a day is useless. Yes you could have more batteries, and because each battery takes a long time to charge you then need a load of battery chargers… not all of us have that sort of money to blow on equipment! “Ah yes”, the reps tell you, “but over the life of the machine the cost is no different from buying petrol.” Well firstly that’s wrong because you’re still having to pay for the electricity, and secondly who on earth buys all the petrol they will need for a machine all at once?

But I digress.

The issue with machinery is less about what it is and more about how it’s used. The best zero carbon emission machine is still not being used sustainably if it’s being used unnecessarily. It’s how you choose to use the tools at your disposal that matters. I’ve found a good way to look at it being to think of the noise of a machine as a major nuisance; how can you effectively do a job causing the least nuisance to people nearby? Little things like preparing your work site so you’re able to use a machine efficiently makes a huge difference, and if it’s possible to manage the garden in such a way that a machine of any kind is needed less frequently then that should be considered a good thing.

The Peat Free Debate

This is a perennial favourite in the tempestuous discussions about sustainability. Peat is an excellent carbon store, and damaging it releases some of its carbon to the atmosphere and contributes to global warming. OK, that’s hopefully fairly well understood; we need to protect peat bogs and their habitats.

There is a small but growing range of peat free composts available to UK gardeners. Some of these are excellent, many are OK, and some are terrible. Much depends on the ingredients of the compost and how it is blended. I won’t go over too much of the same territory that I covered in my post about compost, but in short peat based multi-purpose compost was one of the great horticultural revolutions of the 20th century, and replacing them will not be easy.

Firstly there’s the matter of ingredients. The good peat free composts are based on fine bark or on composted plant matter (although there is a wool compost that is good in some areas- more on that shortly). These composts aren’t the most nutritious themselves (neither is peat) but have a good structure and hold air and water well. Greenwaste composts, composted kitchen waste and garden waste like grass clippings etc, are more nutritious but are heavier composts and tend to hold too much water and too little air.

This brings us to the second point, which is how composts are used. The revolution with peat multi-purpose compost was that you could sow seeds and root cuttings, pot up your plants, improve your soil and even grow plants in pots permanently, indoors and outdoors, with compost from one bag. Potting your plants into greenwaste composts rarely works out well… yet greenwaste composts make excellent soil improvers for lighter sandy soils. The logical thing would be to differentiate between the different types of composts- to abandon the idea of ‘multipurpose’- and to educate gardeners to make their choices about what kind of compost they need. If someone needs to improve their soil and pot up some plants then that would mean buying two different composts, one for potting and one for soil improvement, but that isn’t really all that difficult…

There is still the problem of the supply of raw ingredients. Bark to make bark-based composts relies on forestry activity, but if there’s a drop in the production of timber then there will also be a drop in the production of bark-based composts. Bracken composts well and is used by at least one company that I know of, but what if weather conditions make it harder to harvest all the bracken one year? Greenwaste is always going to be the most plentiful but most compost currently bought goes to into pots so this is arguably the least useful resource.

There is an answer, but gardeners aren’t going to like it: we need to grow fewer things in pots. This isn’t just limited to growing plants for display but it also means dramatically reducing how much compost is used potting seedlings. It means looking for alternative ways to raise our vegetable plants, it means a rethink about what we grow and how we grow it. It probably means a return to direct sowing under cloches outdoors, and the reintroduction of the ‘nursery bed’ for young plants. If you have space for only two or three tomato plants then buying them as seedlings, even grown in peat compost, will be far less wasteful than sowing 100 seeds, potting them all up, growing on the best two or three plants and throwing away the rest!

There are benefits to reducing our reliance on pots. Firstly water consumption will be reduced dramatically as we won’t need to water our pots every day (gardeners quickly learn that plants in pots need a lot more attention than plants growing in the ground!). Consumption of artificial fertilisers, organic or non-organic, will also reduce as plants in soil are better fed by the soil’s natural processes. We will also lose far fewer plants to vine weevil grubs, a problem particularly for plants in pots.

There are people who do not have access to soil for growing, and these people will have no choice but to rely on composts, but even here there are ways that gardening can be more sustainable. The first thing would be to go for fewer larger containers rather than lots of smaller pots; this will give plants plenty of room to develop their root systems and will make them less likely to die. Secondly growing more permanent plants like shrubs and perennials reduces the need to replace compost, providing plants are cared for appropriately.

Bringing this all together

I’ve mused over three elements of current modern ‘sustainable’ horticulture and have, I hope, shown that the issues aren’t actually straightforward. Now multiply this thought process across the whole of horticulture, from how we raise and sell plants commercially to how we maintain established gardens, and you can see just how enormous the question of sustainability truly is. To tackle the whole of horticulture and give clear, defined answers is absolutely impossible; what is appropriate in one garden would be inappropriate in the next, and so on.

Do we abandon hope and just carry on doing what we’re doing? No, but what we must do is step away from only learning gardening techniques and instead we must embrace the idea of gardening as an intellectual, even conceptual, process. We need to learn how to ‘think garden’, and then we can look at making meaningful changes to how we do things. There are advantages to engaging with this process; reevaluating how and why we do things gives us the perfect opportunity to question whether we actually want to keep doing certain things at all. Is the nice big lawn for the kids to play on actually important now they’ve left home, or would it be a good idea to make a new planting area for shrubs and perennials? Do we actually enjoy growing vegetables or would we get more enjoyment from having some fruit trees? If compost becomes scarce and expensive do we really want to do grow lots of summer bedding, or do we need to add more colour to our borders instead?

Sustainability will mean changing our behaviours and gardeners really don’t like doing that, but how arrogant are we if we assume that reducing environmental damage should be masterminded and implemented by others while we carry on doing whatever we want? We need to be ready to change how we, as individuals, do things. For some it might mean big changes while for others it might mean smaller changes, but the aim should be to introduce new practices and retire old practices to the benefit of the gardener, bringing positive changes to how we use our time and resources and to the benefits we reap, rather than facing the challenges of trying to do things as we always have while the gardening world changes around us.