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The Ultimate Guide to Laying Soil on Concrete

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Originally I thought putting soil on top of concrete would be a simple process, but I found much to consider. Therefore, I decided to write a post describing how to put soil on top of concrete.

Although concrete isn’t an ideal surface for putting soil on, it is possible to use it for soil. At least four inches of topsoil must be placed over concrete for grass to grow from the soil successfully. Make sure that the area is well maintained and fertilizers are sprinkled.

In the next sections, we will discuss just how to place soil over concrete, alternatives to doing this, and how putting soil on concrete affects plant and root growth, so please read on!

Things to consider when putting soil on top of concrete

If you intend to lay grass on the soil, drainage is vital to ensuring the grass can grow on top of the concrete. Without adequate drainage, water will collect and prevent oxygen from getting into the soil. This will ultimately result in the grass or other plants dying out.

Look into proper drainage measures when putting soil on top of concrete

This can be avoided if correct drainage measures are taken. Drainage grooves are a great way to drain water from the concrete. The ideal time to form these grooves is before the concrete dries, but this can also be achieved when hardened by using a mortar and concrete saw that a professional should perform.

Look into raised bed gardening before putting soil on top of concrete

If creating drainage is impossible or sounds too strenuous, another option is to create a raised bed before putting soil on top of the concrete.

As previously stated, the heat absorption of concrete can hinder the growth of grass or plants in the soil, particularly in the hot summer months.

A raised bed separates the soil and the concrete, allowing for more soil depth to be laid. The deeper the soil, the easier it is for plants and grass to get nutrients and survive in the long term.

Benefits to raised bed gardening

Raised garden beds make growing possible for everyone with a small land area. They are a great way to turn small patches of concrete or pavement into thriving gardens. Building raised beds are straightforward and requires some basic joinery skills.

Here’s a list of the main benefits of raised beds:

Improved water retentionImproved drainage
Increased growing spacePrevention of soil erosion
The soil on top of the concrete remains warm
but not too hot for growth

Raised beds allow more soil to be put on top of the concrete, increasing the chances that anything planted in the soil will survive.

Four inches is the minimum depth of soil required for raised bed gardening, but it would be better to have twelve inches if possible. This depth would be more than enough soil to grow on. Basically, the deeper you can make the soil, the better chance of things growing from it.

How to make a raised garden bed

Firstly it is important to measure the concrete area correctly and get enough wood to construct a bed that will cover the desired patch. The raised bed needs to be sturdy enough to withstand the weather.

Sizing and content considerations for a raised garden bed

When the bed has been built to the desired size and depth, filling the bottom with a layer of leaves, grass clippings, wood chips, straw, and other organic materials is good. Then add a layer of cardboard on top.

When the soil is added, the mixture will begin to break down over time, turning into rich compost for a thriving raised bed.

To aid you in having a clearer picture of this process, feel free to look into my recent article on just what raised bed gardening is. This article contains the rundown on the recommended soil types and ratios that you should use for raised bed gardening, the number of beds you can consider making, and how to tend and harvest in this gardening method.

Drainage considerations for a raised garden bed

You should make sure that the beds can drain. Otherwise, the soil may become waterlogged, causing the plant’s roots to drown.

Using wood chippings when putting soil on concrete

Wood chippings are also useful when putting soil on top of concrete.

The chippings can be spread to layer and build up the soil, creating more space between the topsoil and the concrete and preventing too much heat from causing damage to whatever is being grown in the soil.

The difficulties of growing grass over concrete

If you have concrete areas in your garden, they can appear unsightly, so you want to cover them in vibrant grass, understandably.

It would be easier to grow grass if the concrete was broken up. Still, I understand that is not always possible economically or because you don’t have the time.

Have a good amount of topsoil before growing grass on concrete

Thankfully, although growing grass over concrete is by no means easy, it is still achievable if you have the proper amount of topsoil. The level of drainage will also greatly impact the growth of the grass. Large concrete areas are liable to pool with water, making it impossible for the grass to get the amount of oxygen it needs to survive.

Check the grass seed and type before planting and growing grass on concrete.

The type of grass seed you choose to plant is also important.

It is best to plant low maintenance and grow almost anywhere – like Creeping Red Fescue on top of concrete.

Applying an even amount of seed to the soil on top of the concrete is essential as this will allow the nutrients to be shared amongst the grass and prevent it from competing.

How the depth of soil affects its ability to grow

If you intend to grow a variety of plants, vegetables, and shrubs on the soiled concrete area, the depth of the soil is probably the most influential factor in whether this will be successful.

If the soil is too shallow, it will be difficult for plants to get the necessary nutrients into their roots. Increasing the depth of the soil allows for these nutrients and moisture to be shared more evenly.

Recommended soil depth for planting on top of concrete

If you are putting soil on top of concrete to grow salads and herbs, a depth of at least twelve inches is necessary.

Other vegetables may require more than the foot soil depth to ensure their roots are kept healthy and minimize the amount of watering you will be required to do.

Raised beds are, without a doubt, the best solution to the problem of soil depth. Beds allow you to control the depth and make the most of the space in your garden. They can also be a fun project to design and make if you enjoy woodwork.

Alternatives to putting soil on concrete

The next few sections will examine what one can look into instead of potting soil on concrete.

Use artificial grass or turf.

I appreciate that for some people, putting soil on top of concrete may be to make your garden more visually pleasing rather than to grow plants on. If this is the case, artificial grass is something worth considering.

Putting soil on top of concrete and successfully growing grass is not easy, so artificial grass provides a time-saving alternative.

A shock pad is installed over the concrete to soften the surface and smooth any imperfections. Holes are drilled through the concrete for drainage, and the turf is installed.

Artificial turf and grass considerations

This isn’t suitable for gardeners out there, but for purely aesthetic reasons, artificial turf can improve the look of your garden in a matter of hours.

There are cheap and expensive options out there, so it is important to research and ensure you get the right turf for your garden.

Drainage of artificial turfs

Along with the pleasantness, most people also have qualms about just how well artificial grass allows for water drainage, comes rains, or watering of plants above said artificial grass.

To aid you with this, I have written an article on just how well artificial grass drains since this is one of the largest considerations. It also covers information about how best to maximize your artificial grass and a list of artificial grass variants that you can look into.


Conclusion on putting soil on top of concrete

Regarding putting soil on top of concrete, one common obstacle you might face is that the concrete can get hot in summer due to its thermal mass. This isn’t a problem in the winter, as the concrete’s warmth will benefit the soil and any plants or grass.

A solution to the problem of the concrete getting too hot is to raise a bed before putting the soil on top of the concrete. This will prevent roots and soil from being damaged by heat. This information and all covered in this article should hopefully give you insight into what you can do with concrete and gardening.

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