What is a weed anyway?

What is a weed?

Turns out that is not such an easy question to answer…

Join Grow Wild as we delve into the world of weeds, investigate their value to pollinators, explore how they have been used for medicine, and try to understand the qualities that make them survive and thrive in the toughest environments.

White cotton plants against bright blue sky.

“A plant whose virtues have not yet been discovered”

In 1878 philosopher Ralph Waldo Emerson said in his essay, The Fortune of the Republic, “What is a weed? A plant whose virtues have not yet been discovered”.

Emerson saw the good in all plants and he hoped that more people would see the potential in plants that didn’t already generate huge wealth. Cotton (Gossypium hirsutum) at that time had played an important part in the American civil war but, like all plants, the ancestors of cotton had at one time been considered weeds.

Emerson said, “And what is cotton? One plant out of some two hundred thousand known to the botanist, vastly the larger part of which are reckoned weeds.”

Weeds can also be plants whose virtues have been forgotten. Many of today’s ‘weeds’ were once cultivated plants but fell out of favour.

For example, in the Middle Ages ground elder (Aegopodium podagraria) was cultivated as a food crop and medicinal herb used mainly to treat gout. These days gardeners do all they can to eradicate it from their borders, without a thought for the value it once held.

Two pastel pink flowers with yellow centres against green leaves.

“An unloved flower”

In 1911 poet Ella Wheeler Wilcox said in her poem, The Weed, “A weed is but an unloved flower!

All plants were once wild and weedy. The ones humans favoured were nurtured, bred and coveted; they were chosen, and they were loved.

The ancestors of our most loved plants were wild, all beginning life as weeds until their value was discovered and their breeding and cultivation began.

Often considered a weed, the wild dog rose (Rosa canina) is a relative to many of our most loved garden roses. Without the dog rose, we might not have one of the world’s favourite cut flowers. Perhaps every weed has the potential to be as cherished a plant or flower.

It is how we view and judge these things that we define what is and isn’t a weed.

Maybe you need to really get to know a weed before you can love and appreciate it.

Field of vivid bluebell flowers.
A plant in the wrong place

Perhaps the most common definition of a weed is “a plant in the wrong place”. This is the definition taught to horticulture students and one that appears to make the most sense.

This definition suggests that the same plant could be considered both a weed and not a weed.

Take bluebells (Hyacinthoides non-scripta). We hunt for them eagerly come Spring, desperate to spot a bright carpet of blue in the woods. But if you plant bluebells inside a tidy ornamental garden, they will probably pop up everywhere in only a few years, so you could end up clearing them away.

What is considered a beautiful, and cherished, UK native woodland flower in one setting, becomes a weed in another.

For generations, humans have decided which plants they want around and which they don't. While you lovingly plant ivy (Hedera helix) in your garden, your neighbour could be ripping it from theirs. It is often entirely personal.

So who decides what is the wrong place, or the right place, for a plant?

Close-up of ivy leaves and flowers.

Human vs. nature

No matter what official definition is used, “weeds” are generally considered to be plants whose negative qualities outweigh the positives.

No plant is a weed in nature, it is human activity that creates the potential for weeds to grow.

Nature is persistent. When humans intervene, some weeds are controlled, while others thrive because we’ve given them more of what they need in the form of sunlight, water, air, and nutrients. 

Weeds are naturally strong competitors, and the weeds that compete best tend to dominate. While humans breed plants for food or aesthetics, nature breeds for survival.

We live on a planet that supports the lives of many organisms besides us, so perhaps it is time to consider what a weed contributes to this bigger eco-system and not only how they affect us personally.

What if we worked with nature, what would a weed be then?

Read more from our 2018 campaign "What is a Weed Anyway?" here.