What is a weed?

What is a weed? Along with slugs and snails, they are probably at the top of the gardener’s hitlist. They seem to grow at 100x the speed of things you actually want to grow on your land, and once you remove them, after hours of toiling, they reappear in the blink of an eye.

But what distinguishes a weed from a plant? I can remember, as a young girl, the shock at learning that daisies were so-called ‘weeds’. We had a garden covered in them, and I spent hours making daisy chains, daisy caterpillars and whatever else my nimble fingers could manage out of them. For me, daisies were beautiful! And I didn’t understand what made them a ‘weed’.

Definition

As I advocate in much of my writing, I think it is important first to look at semantics. The term ‘weed’ itself is quite ambiguous. If we take the online Oxford Dictionary’s definition, a weed is simply:

“A wild plant growing where it is not wanted and in competition with cultivated plants.”

As David Holmgren points out, this immediately renders the term entirely subjective and can not be considered a scientific descriptor of a plant species. Another term that is often employed is ‘environmental weed’, used to describe an invasive species in natural environments, yet this too remain vague and inadequate. What constitutes as ‘invasive’, and what distinguishes this from other species in a ‘natural environment’? The very word ‘invasive’ automatically conjures a very negative perception of weeds, when all it really indicates is an ability for movement. And the ability to move is not necessarily in any way a negative characteristic of plants. In fact, most ‘invasions’ happen in places where there has been human disturbance, a pioneer plant acting as a way to re-balance the soil and surrounding environment.

Holmgren instead offers the term ‘naturalized species‘ to denote a species that has developed self-reproducing populations outside of its original, ‘indigenous’ national range. Here, however, for ease- we will just refer to these self-reproducing species as ‘weeds’.

So we have establish what a ‘weed’ is in terms of its definition, but there are many other questions to consider. Are weeds good, or bad? Can they be useful? Can they be harmful? How can they be managed?

How weeds are useful

Gardeners spend a huge amount of time tackling weeds, but this can be just making more unnecessary work for yourself in two ways. Firstly, this is because weeds are often harmless, and therefore attempting to get rid of them can just be a waste of time. But secondly, weeds can can be nature’s way of improving soil conditions. Permaculture is a keen advocate of ‘reading the landscape’, and weeds can tell us many stories about the land we are working with. They will often grow in areas that have certain mineral imbalances, soils that are compact or water-logged, and to a certain extent can fix these problems;  breaking up compact soil or fixing nutrients. They can also play many other important roles, such as providing shade to establish bio-diversity, acting as ‘living-mulch’, stabilizing soil and water resources, building organic matter , providing habitats or reclaiming disturbed lands. In conventional agriculture, these jobs are mainly performed by adding dangerous herbicides, pesticides and fertilizers. In the organic movement it is often the task of many hands and hours spent weeding. Therefore, by eliminating weeds you can be creating more jobs for yourself to do!   

Therefore, from a permaculture perspective, weeds should be seen as a resource to use rather than getting precious about introducing non-native species. Non-native species can offer a wealth of resources, such as timber, medicine, food, fodder and fuel, allowing communities to ween themselves off the dwindling fossil fuel resources and rely instead on renewable resources. For example, fast growing leguminous shrubs and trees offer much scope for building food forests in permaculture.

To say that we don’t want to introduce non-native plants on account of not wanting to disturb ecosystems is naive. Firstly, native species are likely to move around without direct human contact anyway on account of climate change. And secondly, humans have already caused some disturbance to ecosystems wide and far to varying extents. Weeds are just another way to restore the balance in these environments and development new, healthy systems that can continue to function in a mutually beneficial way with humans.

How weeds got a bad reputation

So in this light, how did weeds get to have such a bad reputation? How has this orthodox view spread that naturalized species are inherently invasive and environmentally damaging? Holmgren looks at how it can be linked to concerns of indigenous biodiversity conservation, which in an Australian context can be more fundamentally linked to a fear of foreigners and a guilt stemming from the dispossession of indigenous people. This can certainly be applied to many other countries around the world.

A key assumption is that most effective and close relationships between species has been created by millions of years of co-evolution. These are generally known as lock-and-key relationships. However, research carried out by Jansen has shown that these relationships don’t actually require that long at all.  While a single species may have taken millennia to develop into its present day form, its relationship with other organisms in its ecosystem can be young and can evolve rapidly. Species may remain relatively immobile, but the relationships they have with their surroundings is constantly changing, and it cannot be said that there is any archetype for one ecosystem. In this light, it has been questioned by Hobbs whether efforts to eradicate weeds and ‘restore’ ecosystems to their original state is simply an expensive ad unsustainable form of gardening. 

Another assumption is that by introducing non-native species, ecosystems can experience species extinction and loss of biodiversity. However, research shows that this is only the case when it concerns animals, and there is no evidence to support that the same applies to the introduction of plants. In fact, the same research has shown that biodiversity increases with the introduction of non-native plant species.

For permaculturalists, a new kind of ecosystem is emerging through a process which has been coined ‘ecosynthesis‘, in which many species are non-native. This is largely a result of human intervention and land degredation. Humans have, and can continue to, play a role in ecosystem evolution. And if we are cautious, and base our decisions on careful observation, we may be able to support ecosystems in a way that protects the environment and supports ecological processes whilst improving the resource values of that system. This could be the key element in moving to less intensively managed landscapes.

How to manage weeds

As we can see then, these ‘naturalized species’ can be an important resource that should be taken advantage of rather than instinctively removed and unused. Maybe ‘celebrate’ is going a bit too far (maybe not?) but we should certainly strive to be more reflective on the benefits of ‘weeds’. Rather than attempting to maintain ‘untouched virgin ecosystems’, our priority should be to establish food security. Permaculture design shows how we can harness all available resources in our transition to a new, more sustainable system, and ‘soften the blow’ when our current unrenewable resources finally pack in.

This is largely food for thought, and I appreciate gardeners wishing to adopt a permaculture approach to growing may want some more solid advice than just ‘weeds can be useful’, because I understand that not all of them are. The point is, that we need deeper reflection of the costs and benefits of eliminating weeds, and a reconsideration of what a weed is.

That aside, here are some tips that I have encountered in my own permaculture pursuits. 
If you are looking to introduce non-native species into your garden, you should generally follow the zoning principle of permaculture, testing the plant initially in the more robust, resilient zones before introducing to the wider ecosystem where it may be more difficult to monitor or manage.

If you already have weeds that you would like to manage in a way that will benefit your crops, there are many things you can do, depending on the weed.

  1. Simply composting weeds can provide mulch and organic matter that will help restore the soil.
  2. A longer term solution would be to correct the imbalances in the soil. Remember: weeds can just be an alarm bell to tell you that something is not right with the soil.
  3. Pruning weeds can prevent the risk of seeds spreading for the next season, meaning a lot less work later on.
  4. Pulling weeds out is generally only necessary for the ones which have invasive roots. Some weeds just need to be cut at the base, which can leave the root in for the transfer of nutrients (e.g rumex), or continuous cutting can weaken the root until it is easily removed (e.g bindweed).

 

 

 

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