Is a sunflower a weed?

Weeds And Sunflowers: Do Sunflowers Limit Weeds In The Garden

There is no denying that sunflowers are a summertime favorite. Excellent for beginner growers, sunflowers are loved by children and adults alike. Homegrown sunflowers are a veritable haven for pollinators in search of rich nectar. While some gardeners may cut the blooms for use in a vase, others who let the plants mature are rewarded with an abundance of seeds.

Regardless of the rationale behind growing these beautiful plants, there is no doubt that planting sunflowers is an asset to many gardeners. However, there is one thing that many do not know – sunflower weed control can be used in the garden. But how can sunflowers stop weeds from sprouting? Let’s find out.

Do Sunflowers Limit Weeds?

While sunflowers are commonplace in the garden, one interesting and frequently overlooked aspect of these plants is that they are allelopathic. Weeds and sunflowers, as with any other

plant in the garden, are always in competition. In order to gain the growing advantage, sunflowers contain chemical compounds that inhibit the germination and growth of other seedlings in the growing area.

These toxins are present in all parts of the sunflower,including the roots, leaves, and seed hulls. The chemicals create a small area in which weeds and other plants have difficulty growing. While this may seem detrimental in the garden, allelopathy (the inhibition of germination) actually has many beneficial aspects. Allelopathic sunflowers can actually help suppress weed growth.

Sunflower Weed Control

With strategic planning, growers are able to use this attribute to reduce weeds within the garden. While the growth of many plants has been proven to be diminished by the presence of sunflowers nearby, other plants show a distinctive resistance.

Ornamental flowering plants such as roses and lemon balm are just a few examples of plants able to withstand and thrive when planted near sunflowers, making them excellent companion plants.

Though there are some exceptions, many garden plants may struggle to grow in the vicinity of sunflowers. While delayed germination may lead to reduced yields, other crops may be more drastically impacted. Potatoes, for example, may have particular difficulty when grown near sunflowers.

When left in the garden, residue and debris from sunflowers can allow the chemical compounds to stay within the garden soil for a longer period of time. To avoid this, remove old sunflower stalks, flowers, and seeds from the growing area at the end of each season. Frequent crop rotation will also help to avoid the buildup of these allelopathic compounds.

How A Sunflower Gene Crossed The Line From Weed To Crop

Sunflowers in Birmingham, Ala. Michelle Campbell/Birmingham News /Landov hide caption

toggle caption Michelle Campbell/Birmingham News /Landov

Sunflowers in Birmingham, Ala.

Michelle Campbell/Birmingham News /Landov

I’m rounding out The Salt’s impromptu Pest Resistance Week (which started with stories about weeds and corn rootworms) with a little-known tale that may scramble your mental categories.

You’ve heard about herbicide-resistant weeds (which farmers hate) and herbicide-resistant crops like Roundup Ready soybeans or corn (which farmers like). But here’s a case — the only one I know of — in which a weed helped create a herbicide-resistant crop.

The story begins in 1996, in a soybean field in Kansas. The soybeans in this field were able to tolerate a class of weedkillers known as “ALS inhibitors.” This line of soybeans had been created through “mutation breeding.”

This technique involves exposing thousands of seeds to chemicals that cause genetic mutations. One of those mutations allowed the resulting soybean plant to withstand the herbicides. (Similar kinds of herbicide-tolerant wheat, rice, and other crops have been created using the same method.)

Among the soybeans in this Kansas field, however, a few weeds also survived after the farmers sprayed their herbicide. The weeds were native sunflowers, wild relatives of the sunflowers that farmers grow as a crop. (As I reported a few months ago, sunflowers are one of a very small handful of crops that originated in our part of the world.)

The farmer contacted Kassim Al-Khatib, who was then a weed expert at Kansas State University. Al-Khatib collected some of the surviving weeds from this field, did some tests on them, and confirmed that these sunflowers were indeed resistant to ALS inhibitor herbicides.

A few months later, through a chance encounter at a scientific meeting, word of this discovery reached Jerry Miller, a sunflower breeder at the U.S. Department of Agriculture’s Sunflower Research Unit in Fargo, N.D. “I couldn’t believe it. I called Kassim right away,” recalls Miller. He saw the possibility of a herbicide-tolerant commercial sunflower created through traditional breeding, avoiding controversies over genetic engineering.

Miller did manage to create such a sunflower — although it took some heroic efforts to get the wild and cultivated sunflowers to exchange pollen and produce viable offspring.

When Miller finally had some herbicide-tolerant offspring in hand, he broke the news to a big meeting of sunflower growers. He told the farmers that, very soon, they might be able to spray ALS inhibiting herbicides right over their sunflowers, killing a host of problematic weeds without harming their crop. “The room got completely quiet,” he recalls.

Today, commercial sunflowers from North Dakota to Turkey contain this genetic trait, and many sunflower growers rely heavily on ALS inhibitors to control their weeds.

What’s the lesson from this tale?

For one thing, that it doesn’t take genetic engineering to create resistance to a herbicide — whether in a weed or a crop. Probably more important, it’s a reminder that our food crops are descended from plants that once grew wild, and the line that separates a despised weed from a valuable crop is sometimes a very fuzzy one. It’s a boundary porous enough for genes to find their way through.

Before you get out the weed killer, let’s make sure that little yellow looking weed isn’t actually a sunflower! But is it a weed or not? Are ALL sunflowers weeds? I’d like to … of course say a definite no! But I thought I’d better look into this a little bit more before I say it with pride and confidence! So here goes.

So are sunflowers weeds? Weed is often used to describe unwanted species of plants. One might call a sunflower a weed, another might call it a blessing. Even though wild sunflowers occur ‘in the wild’, they’re very similar to those people cherish in their gardens. So what’s the difference? Let’s explore what we mean further.

It all started in a soybean field in Kansas City in 1966, where a farmer was spraying crop fields and it so happened that some of the weeds survived!

They were in fact Sunflower ‘Weeds’. Native Wild sunflower seeds was the description given. Why they survived isn’t necessarily the important factor, at least not in this article. Here we’re trying to find out why he referred to them as weeds and whether they are in fact … weeds! Or indeed, why they were referred to as Native Wild Sunflowers – what does it all mean?


After the nuclear accident in 1986, fields of Sunflowers were planted to soak up radiation and clean the soil in chernobyl. A hero of the plant world, if ever there was one.

“If they are a weed, then they’re a weed that we need”

Pamela Anne.

Definition of a Weed

Let’s start with the definition of a weed. We could all easily describe them as unwanted plants that do nothing to adorn our gardens, verandas or patios. Pests that just won’t seem to go away and grow far more rapidly than any plant we can think of! At every time of the year too.

Isn’t that what a sunflower does too? Not only that, but what about the wild orchids that are so lovely, or the poppy … which by the way symbolizes so much we have come to remember! Are we therefore classifying these as weeds too? defines weeds as:-

  1. a valueless plant growing wild, especially one that grows on cultivated ground to the exclusion or injury of the desired crop.
  2. any undesirable or troublesome plant, especially one that grows profusely where it is not wanted.

This seems rather harsh, it would especially seem harsh when applied to poppy’s, orchids and obviously … sunflowers. Am I being biased? Perhaps.

So Who Decides What Is a Weed?

It seems there are two main definitions, or better still, perspectives, that we can apply to ‘weeds’ and it’s not down to the plant itself, it’s down to the individual making the claim or the context in which we find the plant growing.

In the case of farmers, they see weeds as flora and fauna that interferes with their crop growing and harvesting routines. They require spraying with various chemicals so the crop yield remains intact. This is understandable. For them there is an investment they need to keep safe.

The other form, it seems, is for those households that see a plant, (weed), that is simply not wanted in the place it is growing.

In truth, many green looking weeds do have a tendency to grow in the places you don’t want … in between flagstones and the like. But again this seems to be down to the individual and their own tastes.

“A weed is a plant whose virtues have not yet been discovered”

Ralph Waldo EmersonSunflowers in a field …looking wild!

Is a Sunflower a Weed?

Some people do in fact find sunflowers scary, but that’s a whole new article and in fact I mention that in a later post and many other Fantastic Features about Sunflowers.

To some perhaps they’re a weed, to others they’re a valued crop. To me they are certainly not a weed – but my neighbor might see it differently.

Whether it’s in between flagstones or not, it’s a wonderful plant to have around – unwanted or not. Someone somewhere would love to admire it, even if perhaps a few don’t.

In Kansas, the sunflower has been adopted as their state flower. Whilst in Iowa, the plant is listed as a ‘noxious weed’. So the difference in perceptions go beyond single people to whole groups of people. Yet they’re found in all the best florists, they’re a main Sunflower theme at many weddings and they even feature on household product labels, as well as in the product!

What Are We Comparing Them With?

Could it be that some of us are looking upon sunflowers more as flowers? Because if we compare them with many of the grassy type weeds and stingers we find, then it appears to be more enchanting than those? Is there an unconscious bias going on here?

All things are beautiful in the eyes of mother nature, we should I’m sure, all think the same. But we probably cannot help but look upon a sunflower, and other flowering wild flowers a little more affectionately than the raggedy, but charming weeds and grasses we also see much of.

Sunflower, hiding behind a weed!

When Sunflowers Are Wild Flowers

A Sunflower is a wild flower …when it’s seen in the wild. It’s also a wild flower when it’s not used for agricultural purposes, or in garden centers.

However, there are varieties that are more renowned for dwelling in fields and on roadsides than in your usual garden center.

Sunflowers seen growing in the wild, and not cultivated for crops or gardens, have probably grown from seeds dropped by birds or foraged by animals in the wild.

Of course, Sunflowers may not seem so attractive to you (perish the thought). So if you were to find a sunflower on your patio – and you didn’t want it, then what should you do about it?

Weeds For Sale!

Before you decide to take a spade to a sunflower, ask yourself a few questions first of all about the options. Or look at it in alternative ways, such as…

  1. Is it in a place that is really out of place in your garden?
  2. Could you make a feature out of it, add other plants around it to build a theme.
  3. Transplant it carefully into another part of the garden.
  4. Offer to move it to a neighbor or friends garden as a gift.
  5. Use it to help children learn to care for a sunflower. Sunflowers have a fairly short season, so it’s worth using it whilst it’s around.
  6. Leave it to feed the wildlife. They act as food for many loved species of birds and animals.They provide shelter, and even a place for butterflies to lay eggs.
  7. Bees value sunflowers as much … if not more than they do other plants. They contain between 1000 to 2000 pockets of nectar for bees. It’s a bee feast!

To me there’s a line to be drawn. Nature will love you for keeping that ‘unwanted’ friend in your garden, in any way possible.

In Conclusion

When it comes to sunflowers, and whether they’re wild flowers, or weeds, it seems to be more to do with the context you find them in, and in the eye of the beholder than it does about the plant.

I look back now and wonder if I put a little too much of my own stamp on this article. But in my defence I’d like to point out that, I run a sunflower website, so I’m not sure what one would expect! Also, I’ve loved sunflowers all my life. So for those reasons I’m going to forgive myself … just a little bit.

But I’m probably not alone…

Others hopefully see what I do too. Sunflowers seem to hold a beauty all of their own, regardless of where you see them. It almost doesn’t matter. So, I’m definitely going to be the first one to say, they’re not weeds, they’re flowers, and stunning ones at that!

That’s why I’m wild about sunflowers…

Related Questions

Are Sunflowers Wildflowers? If you find a sunflower, and it’s in a wild area with other various forms of flora and fauna. Then you can certainly class that sunflower as being wild. But only as a basis on the place in which you discovered it. If grown in a garden, or as a crop, then the sunflower is not a wildflower at all.

Can Sunflowers Grow Anywhere? They are a very resilient plants. They can grow in the poorest of soils. Sunflowers can grow in fields amongst other crops, in gardens, grass verges and sidewalks. However They can not survive the harshest or extremest of environments, such as deserts, snow or freezing weather.


Many broadleaf weeds bear some bright and beautiful flowers that can mislead a homeowner into thinking that the plant is harmless. However, reality can’t be farther from the notion. Broadleaf weeds are often aggressive and take away the essential nutrients from the soil, rendering it less supportive for turfgrass.

Sunflower (Helianthus) is one such broadleaf weed that can completely take over your yard if neglected. It is common to most parts of the country, including the transition regions. The bright yellow flowers are beautiful to look at, but the weed can overwhelm any yard within months.

In this article, we will learn some details about the weed itself and then look at some of the methods to eliminate it from the lawns.

What is Sunflower (Helianthus)?

Sunflower plants can read a height of up to 6 feet and feature an attractive flower at the end of each stalk. Although the plan is consumable by livestock and can be desirable on ranches and farms, it has no place in your yard.

Sunflower is one of the most voracious consumers of nutrients from the soil and can steal valuable nutrients from the turfgrass. If correct measures are taken, you can fully eliminate this menacing weed from your yards and protect your turf from future infections.

How to manage Sunflower (Helianthus)?

Like most broadleaf weeds, sunflower also can be managed effectively without the need of a herbicide. The best way to tackle this weed is to eliminate it before it seeds and spreads across your lawn.

There is no alternative to good cultural practices for controlling weeds in your yard. Always follow the best lawn care practices to reduce the susceptibility of your turf to weeds. Here are some tips to get rid of sunflowers from your yard:

  • One of the most effective methods to tackle a patch of sunflower plants on your laws is to snip the heads of the plants with pruning shears. This ensures that when they seed, the spread will be limited. This is especially important if you want to get rid of the weed in steps and can’t finish the job in one go.
  • Cut the stem so that it is slightly above the ground. The chopped stems make an excellent addition to the compost if you have one.
  • The root of the plant is in the shape of a ball and needs to be dug out completely. While digging to eliminate the root, make sure that there are no bits and pieces left behind. Digging a small trench around the root will make sure that you get it completely out without leaving any bits behind.
  • If in case any seeds are left behind, make sure to pick them up and dispose of them.
  • The chemical herbicide glyphosate can be applied to patches of sunflower if the patch is too difficult to manage using the manual method. However, be cautious while applying chemical herbicides and consult with weed experts before you decide to go the chemical way.

Something to take home

Weeds such as sunflowers can be problematic if left unattended. Make sure that broadleaf weeds are eliminated from your lawn as soon as you spot them. Weed control services can easily take care of sunflowers. We hope that you learned something new about this annoying weed and if you spot it in your yard, you will be able to get rid of it easily.

Leave a Reply

Your email address will not be published. Required fields are marked *