Walking around your property only to notice plants growing wild can sometimes catch us by surprise. For example, did you recently see greenery sprouting from cracks in the sidewalk or your driveway and didn't know this was possible? How do tiny plants emerge from concrete?
Well, we've done plenty of research into this topic and have the answer below!
Yes, plants will grow through concrete if they have a place to squeeze in between. Generally, a microscopic crack in concrete is to blame for rogue plant growth, which can be hard to prevent over time.
Especially if you have trees growing near concrete, that heightens the chances of cracking and plants emerging from the rubble, even though concrete is super sturdy.
As we start this article, we will cover everything concrete and discuss why you see plants growing through yours. Whether it's your sidewalk, driveway, pool deck, or whatever concrete surface you maintain: we're here to help. With that said, let's dive right into this topic and figure things out!
Why Do I See Plants Growing Through My Concrete?
One of the main reasons you see plants sprouting from concrete is microscopic cracks under and above the surface. As we said, these tiny cracks allow plants to travel through concrete to the surface.
Therefore, if you see plants sprouting from the top of your sidewalk, driveway, or other pathways: there's likely quite a bit of microscopic cracking below what you can see.
This is pretty normal, however. Over time, your concrete may shift, or the ground below it may settle, causing hairline cracking. When this occurs, you can expect more plants to emerge, often becoming full-blown concrete jungles if left unattended.
There aren't many ways to fix this because the concrete is already poured and settled. Therefore, you might have to spray herbicides on your sidewalk to keep the plants at bay.
Sometimes, mother nature will have her way: whether we like it or not. If cracking becomes noticeable or dangerous to people walking/using the concrete, you need to take more significant action.
What Causes Concrete To Crack?
One of the leading causes of cracked concrete is pressure and ground movement. Usually, cracking happens when shrinkage forces become greater than the strength of the concrete.
For example, if the ground moves too quickly or the concrete's underlying foundation becomes off-center, that's when pressure forms.
The area receiving the most pressure is likely to crack, allowing plants to come through. This is often unpreventable, considering the ground is constantly settling and adapting.
Sometimes, nearby construction can cause your sidewalk or driveway to develop hairline cracks, eventually leading to green sprouts throughout your concrete.
As we covered, you can't always prevent or entirely fix this since the ground is too powerful. Luckily, if you have an experienced professional pouring the concrete, you shouldn't be dealing with cracks or plant growth anytime soon.
You might also want to avoid planting trees or large shrubs near concrete, as their roots can also travel under it, causing cracks.
Even though roots aren't necessarily strong, with enough pushing against concrete: cracking is possible (and likely).
Do Trees Cause Cracks In Sidewalks?
Yes! Tree roots are often blamed for lifted, cracked, and destroyed concrete sections. If you've ever walked through a city or somewhere with tree-lined sidewalks, you've likely tripped or almost lost your balance because of a raised concrete area.
That's because the roots from the nearby trees have traveled under the concrete and tried to escape. Typically, a plant doesn't know what concrete it is, so it'll try and extend its roots through it.
This may start with your tree expanding its roots underneath the nearby concrete. However, these same roots will grow and expand over time, applying pressure underneath your sidewalk/driveway.
Pressure is what causes microscopic cracks. Once these cracks form, they'll expand with ground movement, allowing plants to spread to the surface.
Whether you live in the city or suburbs, tree roots are not to be tested. If you have a tree growing near a sidewalk (within 10 feet), who's to say the cracking hasn't already started?
According to Groundworks, even the most delicate tree root systems can cause hairline cracking. Concrete is hardy, but not when pressure is involved.
How Far Should A Tree Be From Concrete?
You want to plant a tree at least 5-10 feet from a concrete sidewalk, driveway, or other structure. Depending on the tree species and variety, its roots may be incredibly large and powerful.
However, smaller trees and shrubs will be safe between three and four feet from a sidewalk. That's because their root systems won't expand 20-50 feet in every direction as larger plants will.
On the other hand, many experts suggest larger trees being more than six feet from a concrete surface. You don't want a massive tree too close to your concrete, or cracking is likely to occur.
Furthermore, your sidewalk or another concrete surface may become more damaged than microscopic cracks. Some roots are powerful enough to lift entire sidewalks and crack them in pieces.
Younger trees are easier to relocate, so if you accidentally planted one too close to your concrete, try transplanting it ASAP. Moving big trees can be dangerous, often killing the tree and damaging the ground.
The longer a root system has in the ground, the more expansive it will become.
How Do I Get Rid Of Plants Growing Through Concrete?
One of the best ways to get rid of plants growing through concrete is by spraying them with herbicide. Specifically, we recommend a glyphosate-based product, which will kill whatever plant it touches.
One of the benefits of using glyphosate products (Roundup, etc.) is that it targets the enzymes a plant needs to grow and stay alive.
Therefore, a quick spray across your sidewalk's problem sections will do the trick. That said, you don't want to spray a product that will stain your concrete.
Sometimes, specific formulas can damage concrete and seep into its pores. That will cause discoloration and might even make hairline cracking more noticeable.
Try and use a clear, easy-to-wash-off herbicide product on concrete to avoid problems. The last thing you need is stained and plant-ridden concrete throughout your property.
In contrast, many gardeners also recommend going a greener route. You might want to try pouring boiling water on your sidewalk to stun and kill weeds instead.
Vinegar is another option for sidewalk weed killing, as well as salt. You don't always need harsh chemical products to solve this issue.
Ortho GroundClear Weed & Grass Killer
This herbicide works around and on concrete, shows results within 15 minutes, is certified organic, works on all types of weeds and grasses, and comes with a spray wand.
Will Plants Growing Through Concrete Destroy It?
If you allow a plant to grow big enough through concrete, it can cause significant damage. As we mentioned before, the roots of trees and large shrubs can quickly spread beneath concrete and cause it to crack.
Of course, this will start small. You might see hairline cracking after a while, eventually noticing green sprouts from the concrete surface.
Once this begins, you want to try and control the plants. Whether you use an herbicide or manually pull each plant from the concrete, you need to pay close attention to where they're growing.
A mistake many gardeners make is letting weeds and plants run rampant. Over time, these once harmless cracks in the sidewalk, driveway, and patio could become devastating.
Furthermore, you might even need to completely replace sections of your concrete if they lift or develop severe cracks. So, what starts as a small hairline crack can soon become your worst nightmare.
Does Concrete Affect Plants?
Since concrete isn't toxic, it shouldn't negatively affect plants nearby. However, pouring concrete over a root system will cause it to either die or fight back, which is bad in both cases.
Remember, concrete is sturdy when there isn't uneven pressure. That said, the second uneven amounts of pressure become strong enough below your concrete surface; that's when cracks and plant growth will begin.
Moreover, if you pour concrete around too much of your garden, this could cause infertility in the soil. When there isn't enough oxygen moving through the ground, your plants will all suffer.
So, create a space for both and leave room between trees and concrete.
What Happens If You Ignore Cracks In Your Sidewalk Or Driveway?
If you ignore cracks in your sidewalk or driveway, expect significant damage down the road. As we covered, hairline cracking won't stay microscopic forever.
Especially once plants find their way into these cracks and continue to grow, bigger problems become a reality. For example, if a tree's root system adventures below and through concrete, another tree can form in the sidewalk/driveway.
The same applies to shrubs and weeds, as many of these can self-seed and multiply. So, if you see plants on your sidewalk or driveway, pull or spray them immediately.
To Wrap It Up
Whether you have plants growing through your concrete or think this may become a problem, it's essential to form an action plan. Since hairline cracking in concrete is inevitable, you want to try and keep a close eye on your sidewalks, driveways, patios, etc.
When you see green sprouting, note the area and spray an herbicide. Moreover, you can try boiling water, salt, vinegar, or hand pulling.
Also, keep trees ten feet from sidewalks to be safe, although smaller species should be okay within 3-4. The happy medium for most gardeners is around six or more feet.
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