Using Weed Killer Safely Around Trees and Shrubs

It’s that time of year again — you see pesky weeds pop up throughout your garden and yard, and it’s time for war. You crack open your weed killer and prepare to douse your enemy… but wait! Tossing a potent weed killer can quickly kill off other garden vegetation, like trees and shrubs.

Herbicide damage can not only lead to unsightly symptoms (like browning leaves) but can also open your trees up to other problems, like pests and diseases.

Read on as I go into using weed killer safely around trees and shrubs without causing damage and destruction in your outdoor space.

Weed Killers That Are Safe for Trees and Shrubs

From home remedies to powerful herbicides, there are numerous ways to fight the war against pesky, unsightly weeds. Here are a few of the most effective weed eradication methods around. 

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Vinegar Concentrate

While most home remedies are less than effective, more and more gardeners are raving about vinegar concentrate. Highly acidic and fast-acting, horticultural vinegar is capable of destroying weeds right before your eyes. 

The use of vinegar does have significant drawbacks and comes with hazard warnings. If used too often, a vinegar mix can harm the environment by causing damage and depleting nutrients in your soil, as well as harming insects and other wildlife. 

High concentrations of acetic acid (higher than 5%) can be very harmful to humans, too. The effects of exposure to high doses of vinegar can include chemical burns and dermatitis and even chronic bronchitis and tooth erosion if ingested. 

If you are planning on using a vinegar concentrate formula to get rid of weeds then you should always protect yourself by wearing protective goggles, gloves, and long-sleeved shirts.

You should also take care when using vinegar around any plants, trees, and shrubs you wish to remain intact. Vinegar concentrate is labeled as a non-selective formula. This means it will kill anything it comes into contact with. 


Casoron is a popular pre-emergent herbicide that is widely used by gardeners to combat weeds. Casoron is most effective when applied in the early growing season (before your weeds come in). 

This mighty herbicide works over six months, so you only need to use the product once for it to work throughout spring and summer. You mustn’t over-apply, as Casoron will remain active in your soil and can cause damage to your lawn, soil, and neighboring trees or shrubs. 

While Casoron is a selective herbicide, meaning it can safely be used around many varieties of trees and shrubs, it’s deadly for fish and earthworms and has potential environmental and personal health consequences. As a result, extreme care should be exercised when handling this product. Always wear gloves and a mask, and make sure to wash your hands thoroughly after use. 

You can find products containing the active ingredient Casoron in a variety of stores depending on the region in which you live.

Weeding by Hand

Indeed, the safest method to keep your trees and shrubs alive is to weed around them by hand or with a weed puller. But I don’t have to tell you the downsides of this method. 

If you have a sprawling yard, picking out weeds by hand can take hours, even days. It’s tedious work and can be hard on the back and knees. You also need to take care to remove all of the weed, including the entire root and any rhizomes. If you leave any bits of root behind, they will likely re-root and cause new weeds to pop up.

Herbicides To Avoid Using Around Trees

There are some herbicides that should be avoided when weeding around trees as they can be especially harmful. Once you damage your tree, it can be difficult, if not impossible, to return it to full health. One herbicide in particular to avoid is the active ingredient glyphosate. 


Glyphosate first appeared in the 1970s and, due to its highly effective ability to eradicate weeds, is still used widely today. Glyphosate comes in various forms, including liquid concentrate, powders, and granules, and as a ready-to-use liquid. 

It is known to be so effective because it prevents plants from making certain proteins that are needed to grow. It does this by stopping enzyme pathways, which are necessary for plant growth. 

However, Glyphosate is a non-selective herbicide. This means that it will kill any plants it comes into contact with. As a result, you must keep this product away from your trees and shrubs. 

In addition to Glyphosate harming trees, it is known to cause harm to the environment and to humans. Health organizations deem it a potential carcinogen (although the EPA contests that it is a carcinogen) and can kill bees and other vital insects. Sadly, this herbicide is known to damage ecosystems because of the way it can disrupt food chains, pollination, and so forth. 

Signs Of Herbicide Damage

Even with years of gardening experience and know-how, and while I always try my best, sometimes damage to trees and shrubs is near impossible to avoid. If you suspect your trees are suffering from herbicide damage, there are a number of tell-tale signs you can look for. Here are a few I’ve seen in my own lawn and garden:

Yellow Leaves

Yellow leaves are often the first sign of herbicide damage. They call this phenomenon chlorosis, where leaves lack adequate chlorophyll, and as a result, their leaves turn yellow.

If you notice your tree’s leaves turning yellow, this is a sign that they aren’t getting the nutrients they need or a herbicide may have harmed them. Make sure to cut back on herbicides once you see leaves turning yellow. You could also try flushing the soil out around the affected tree, shrub, or plant with water. 

Brown Edged Leaves

If you notice your tree leaves turning brown, this is also a sign that it is suffering from herbicide damage. Browning leaves are also referred to as necrosis, which is a sign of the plant dying. 

Thankfully, if you notice this happening on adult trees, then the chances that they will die are relatively slim. It usually just means that the leaves affected will die and fall off. However, if this happens to a younger tree, it may not recover.

Cracked Bark

Another significant sign that your tree is suffering from herbicide damage is the appearance of cracked bark. A lot of herbicides (like Glyphosate) can weaken the tree bark structure. This makes the tree susceptible to injuries, such as freeze-thaw injury or diseases and pest infestations. 

If you see excessively cracked bark on your tree, you should take extra care to avoid using herbicides around your tree to prevent further injury and death. 

It may be possible to ‘repair’ the cracked bark and protect against disease and infestations by painting the area with a protective layer of asphalt-based wound paint. However, many modern arborists advise against this practice and instead recommend letting the tree heal itself.

Twisted or Crinkled Leaves

A lot of herbicides contain Glyphosate or 2,4-D, which is a component that curls the leaves it comes in contact with, causing the tree to not function correctly on a cellular level.

When applying a liquid herbicide across large areas, it is possible that spray particles can be carried by the wind and accidentally come into contact with plants that you may want to keep alive. I always recommend spraying on still days because even a slight breeze can cause particles to blow in all directions, thus causing unnecessary damage.

Spraying Weed Killer Around Shrubs and Trees

If you decide you still want to spray weed killer around your trees and shrubs, there are ways to limit the amount of damage done to nearby plant life. Follow the tips below to safely administer weed killer so that your landscape plantings remain safe, happy, and healthy. 

Young Trees With Green Bark

The younger the tree, the more vulnerable and susceptible it is to threats such as disease, dehydration, and herbicides. If you have young trees in your yard, you should avoid spraying them with herbicides at all costs. 


You’ll want to avoid any seedlings when spraying with herbicides. Seedlings are even more susceptible to damage and injury from herbicides. If you damage a seedling too young, the chances that they can recover are very minimal. 

Above-Ground Roots

Roots are how trees absorb nutrients. Without healthy roots, a tree cannot continue living.

Whilst exposing the roots of your tree is not always detrimental, it can make them much more susceptible to outside threats, like herbicides. If you do plan to use herbicides, be very careful not to spray around any exposed roots. This will cause significant damage — possibly irrevocable damage depending on the severity of the herbicide, the tree’s age, and the tree’s health.

Spray Drift

One of the more common problems when using herbicides is that the chemicals can drift from one plant to another and cause irreparable damage. This can also occur if neighbors use herbicides on a windy day. The chemicals may get picked up by a strong gust of wind and land on your trees and shrubs. 

If you are using herbicide, make sure only to apply it to your weeds when the wind is low to reduce the chances of carrying it to your other plants or to your neighbor’s yard. It helps to use larger droplets with lower pressure, as herbicide drift will increase with application pressure and speed.

If your neighbor uses herbicides, try protecting your trees or shrubs with a tarp or blanket, especially during the day and the following days after they apply the herbicides. 

Shield Vulnerable Plants

If there are particularly vulnerable trees (ones suffering from disease, young trees, etc.), you might want to take extra care to shield these trees while you apply herbicides. 

You can cover your trees and shrubs with a sheet while you apply the herbicides. Make sure to keep the covering over the trees for the entire day as wind gusts can spread herbicides around until after they have dried. 

If you think herbicides have harmed your plants, you should use soap and water to scrub the herbicides on your tree trunk and then rinse thoroughly. Start by spraying all affected areas of the tree liberally with water. Once soaked, wash the tree with a soap and water combination. Follow this up with another good soak with water.

Water is vital to the recovery process as it leaches herbicide formulas from the root systems. 

Prevent Weeds In the Landscape

All in all, the most effective way to remove weeds from around trees is to prevent the weeds from growing in the first place. Here are some low-risk ways in which you can prevent weeds from growing:

Landscape Fabric

Some gardeners choose to put down landscape fabric around their trees and shrubs. This is a tough, green or brown fabric that you put over the soil to suppress the growth of weeds. While it is effective, some gardeners don’t like to use this method because it looks a little unsightly.

Furthermore, the fabric around the trees also makes it difficult for tree roots to absorb water, which ultimately can have as much of a negative effect on the tree’s health as an herbicide would. 

To avoid this, always select a water-permeable landscape fabric such as Kdgarden Premium Pro Weed Barrier Landscape Fabric. You should also provide extra water to young trees or in dry weather.

Organic Mulch

One of the most effective ways to prevent weed growth is through the use of organic mulch. This is because mulch prevents weed seeds from reaching the soil. It also blocks sunlight, which, in turn, further suppresses their growth.  

Additionally, mulch is good for your trees and shrubs as it delivers an extra boost of essential water and nutrients to their root systems. 

Not only is organic mulch effective but it also doesn’t harm your trees, shrubs, insects, soil, or any other living being that comes into contact with it. As a result, most gardeners choose to use organic mulch since it is the safest method to prevent weed growth. 

Plant Ground Cover

Another fun way to fight back against weeds is to use other plants. That’s right… this genius method uses plants to take up space instead of leaving that space empty for weeds. 

Instead of using unsightly mulch, you can use pretty perennials to cover the earth. A thick planting of flowers can prevent weed growth by keeping sunlight off the soil. Furthermore, they steal essential water and nutrients that would otherwise go to the weeds. 

Final Thoughts On Treating Weeds Around Shrubs and Trees

If you have troublesome weeds sprouting up in your yard and garden, you may want to whip out that herbicide and douse it all over your yard. 

Unfortunately, doing this will cause severe damage and even death to your trees and shrubs. Instead, try some more natural solutions. If that doesn’t work, use herbicide carefully and take extra steps to fully protect your garden. Your trees and shrubs will thank you.