Building a healthy lawn on concrete often leads to debates among homeowners. Concrete is not the best place for growing grass, so creating a base onto which these plants can live is the only way to achieve success.
Nevertheless, it may be a good idea to remove the concrete first, as it will guarantee the best result. If it is not possible, make sure there is enough topsoil and proper drainage. Besides, growing grass may break down concrete over the years provided it has enough fertilizer, water, and nutrients.
So how to grow grass on concrete?
To grow grass on concrete the first thing you have to do is make sure there will be drainage if not you should drill some drainage holes. Next, create a soil base and then supplement that base with a nice thick layer of compost or manure. Finally, lay the turf on top of this base and with proper care, it can thrive.
Remember that such a lawn requires more attention since the soil is not deep enough, and the roots of your grass cannot reach the water. For this reason, you should always keep the soil moist and fed.
Can You Grow Grass Over Concrete?
Yes, you can. However, there are specific circumstances that will help your grass can grow over concrete.
- Concrete is very porous, with thousands of small holes and pores able to hold water.
- The roots of the grass are tough enough to develop and thicken, consuming the concrete base.
- The concrete is covered with a layer of sand, making the grass seeds root and develop, building a healthy mat and a strong root system.
It is possible to grow grass over concrete, and many gardeners do it. Still, the roots of the grass need a proper bed that is rich in moisture and nutrients to support them. For this reason, you need to provide a thick layer of soil or soil-like mixture over that concrete block.
The depth of the soil layer determines its fertility, so if you make it deep enough, you will be able to grow not only grass but also many other plants, including small trees.
A good example that comes to mind is Millenium Park in Chicago, which was built over the concrete top of the underground parking garage. You will find numerous medium and large size trees and beautiful green lawns there.
Planting grass over concrete is a perfect way to transform your landscape and make your backyard neat and cozy.
It allows you to hide a graveled area or a pesky old walkway which appearance you hate under the beautiful green carpet, giving you and your family a place to play on.
Although concrete is not the best base for grass, growing grass on it is still possible.
The main factors you need to take into consideration are the amount of topsoil and the proper drainage. Smaller concrete walkways or other areas are more likely to be successful since large concrete pads may prevent the water from getting to the roots.
How Deep Does Soil Need to Be to Grow Grass?
Dealing with buried bricks and concrete is tricky since there can be decomposable matter like wood involved. The decomposing wood causes the sinking of the surface and the holes in the soil. For this reason, you need to ensure these materials are deep enough.
Lawn grass has a shallow root system, so you can put grass seed or lay turf on concrete if you cover it with at least 4 inches of soil.
It is difficult to build a lush green lawn on concrete unless the soil layer is very thick (at least 15 inches).
The concrete base has been known to suck the moisture and nutrients out from the soil, making it infertile and killing all the plants that grow on it.
Minimum Soil Depth For Grass Over Concrete
The roots of your grass need to penetrate deeply enough, so the minimum soil depth should range from 10 to 12 inches. Besides, alkaline, lime-rich concrete with its high pH level is toxic for most plants.
You should make the soil layer as deep as possible to avoid potential problems.
If possible, pull up all the shallow bricks or concrete blocks for sure. It is also a good idea to talk with the original builder and find out what is the type of concrete and how deep it is. The debris will not be a problem if it is 3-4 feet below the lawn surface.
You can cover your soil layer with topsoil mixed with decomposed organic matter to improve its fertility. Next, grade it with a grading rake and roll it with a water-filled roller. If you still see holes or lumps, grade and roll the surface once again.
How Do You Lay Grass On Concrete?
Check if there is any loose concrete on the area you wish to build your lawn on. Before putting down topsoil, rake all the loose concrete away and dispose of it. Also, make sure water can properly drain from the chosen area.
Apply at least 4 inches of topsoil to the concrete area. You can use a measuring stick or a ruler to measure this layer and ensure you have the correct amount.
Fertilizing the topsoil is the next step you should take. Use either the compost from your compost pile or fertilizer from your local garden store and mix it well with topsoil. Next, plant the chosen grass seeds or a mix of different grass seeds.
Maintain the area and make sure there is good drainage, which allows your grass to grow on concrete.
Using sod is probably the best way to build a new lawn on concrete since you can fix any depressions or other defects when laying the roll. If you prefer planting grass seed, make sure to use a mechanical spreader and not to throw seed by hand.
An established grass is strong enough to prevent weed appearance, so you will not need to use weed killers. However, weeds may appear if you mow your lawn shorter than 3 inches.
There are also a few recommendations for taking care of a lawn grown on concrete:
- Do not use fast-release fertilizers. Slow-release organic fertilizers are much better for the health of the lawn.
- Water your grass deeply and allow it to dry before watering again.
- Make sure the sod has put roots down into the soil before mowing your lawn.
You Need Drainage to Grow Grass Over Concrete
Grass will never grow healthy on concrete without a good drainage system. You should make your lawn slightly sloped and clear at least 10 inches of debris from its surface to make drainage suitable for growing grass.
Your lawn should not be perfectly flat. Otherwise, water will always sit on its top.
The 1-2% slope is the best choice for the grass that grows on concrete. Besides, you can dig channels along the sides of your lawn or install perforated drain pipes to allow the moisture to slowly filter through the soil.
Problems Caused By Concrete Under the Lawn
- The layer of soil is often too small to hold enough water and keep your grass alive, so it may die each summer.
- Grass can grow fine until the summer heat hits, burning out the grass. The same situation is with septic tanks that are not buried deep enough. In this case, the only option you have is digging it up and removing the concrete.
- Any grass requires a deep layer of soil, not just a few inches. If you plant it on a thin layer of topsoil, grass will be weak and yellowish.
- The grass grows over concrete until it has enough moisture. Like any other plant, it gets water from the soil below it. The concrete base prevents the moisture from getting to the roots of your grass, leading to its death.
Best Grass For Growing On Concrete
Zoysia grass is probably the best grass for growing on concrete.
It is an excellent option for gardeners who hate taking care of their lawns. Zoysia grass always stays green and beautiful and does not require frequent fertilizing or watering.
Zoysia is not grass in the strictest sense; it is a vine-like plant that is quite similar to grass. Furthermore, it has a well-developed root system, which helps Zoysia grass to kill any weed.
Creeping Red Fescue is also a great option. This grass type is considered one of the best plants to grow on concrete or other unfavorable bases since Red Fescue grows just about anywhere.
Besides, you may mix Red Fescue with Zoysia grass to achieve the best result.
Alternatively, Use Artificial Grass Over Concrete…
If you don’t want to go through the drama of laying soil and turf and sorting out the drainage for real grass then using artificial grass is a great option.
Artificial grass is a good choice if you want some green stuff for aesthetic reasons as you can lay it over concrete and it looks instantly good.
Apart from aesthetic reasons another great idea is to lay artificial grass over a kids’ play area, it’s not exactly bouncy but it should offer a little bit of protection from any accidental falls onto the concrete flooring.
I would definitely recommend installing artificial grass over concrete if you don’t want to use real grass as it is just so versatile and softer than hard concrete.
This means it can be used for anything from a kids’ play area to a covering for your patio where you use tables and chairs whilst eating barbecued food or even for an exercise mass when you need to work off all that barbecue food you’ve been eating.
How To Lay Artificial Grass Over Concrete
I suppose you can simply lay some artificial grass straight over concrete and there you go, you have artificial grass over concrete. If you want to make a good job of laying your artificial grass then these are the steps you should take:
The first thing you have to do is check the condition of the concrete as it’s not advisable to lay artificial grass on concrete that is in poor condition such as it having major cracks, being uneven, or having holes on it.
Next, you should give the concrete area a good wash because you don’t want any dirt underneath as that could encourage fungus or mold to grow. (Then give it time to completely dry)
If when you wash the concrete you notice that it doesn’t drain properly or puddles have formed you may need to drill some drainage holes otherwise your artificial grass could become a giant puddle.
Lay some artificial grass foam underlay. This is important because it will give your artificial grass a more realistic feeling so when you walk on it, it won’t feel completely like concrete it will have a tiny bit of bounce.
Next, you need to apply some special glue around the edges onto the concrete and stick the underlay on it so that your lawn doesn’t slip around when it’s used.
Now you will need to cut the artificial grass into the correct shape and make sure it all lines up, use artificial grass tape for any joints in the grass.
The final step is to apply more glue around the edges, this time on top of the underlay and stick the artificial grass layer onto it.
You should stay off the grass for at least 3 hours to give the glue time to dry, you can then enjoy your new artificial grass that should last for years without any maintenance.
As you can see, growing grass over concrete is not the easiest task for most homeowners. Concrete buried under your lawn may cause many annoying problems, and it can be quite hard to fix them. Still, by making the soil layer deep enough and choosing a durable type of grass, you can get a green lush lawn in your backyard!