A Raised garden bed on concrete is awesome, as it helps you to plant in places where you could not have planted.

Raised Garden Bed on Concrete

Even though this gardening technique is well-recommended, it is quite technical to start and maintain.

If you’d love to learn how you can garden on patios, read this article.

How Can You Build a Raised Garden Bed on Concrete?

You can build a raised garden bed on concrete by gathering your needed materials, determining the location, size, and shape of the bed, lining the bed, and adding soil and compost. Remember to perform regular maintenance on the bed so that you can use it for a very long time.

– Gather What You Need

To garden on concrete blocks, you need to gather some materials.

Gather What You Need

Here are some things that you’ll need:

  • 2×6 or 2×8 lumber: If you want the bed frame to be made of wood, you should use lumber. You can use either untreated or treated lumber.
  • Drill and screws: 2.5-3 inches long screws are ideal for fixing the lumber to the ground.
  • Weed barrier fabric: You need a liner to prevent toxic chemicals in the frame from leaching into the substrate.
  • Soil and compost: What else will you be planting on if not the substrate?
  • Plants or seeds: You want to go for plants with shallow roots.

If you do not want to make the bed out of wood, you can use galvanized steel or whatever material is available.

– Determine the Size of Your Raised Garden Bed

When building your elevated bed garden, you should determine the size that is right for you. Most beds are 3-4 feet by 6-8 feet. However, you can go for larger or smaller beds if you like.

You should also consider the available space so that you do not build a bed that will block the way. Using a measuring tape, map out the area where you want to build your bed.

– Prepare and Lay Out the Lumber or Frame

When you have gotten your preferred material, it is time to start building. If you are using lumber, make use of a saw to get your desired size and shape. For lumber frames, drill holes through the frame, into the concrete. When the holes are ready, fix the lumber to the ground by using screws.

Using your hands, check if the frame is stable or well attached to the ground. If the frame is shaky, make sure that you screw the unstable parts.

– Line the Garden Bed Frame

You need a weed barrier fabric for your bed.

Here are some uses of a bed liner:

  • It prevents roots from damaging the concrete: Sometimes, the roots of your plants can penetrate the concrete below and damage it. You can prevent this by lining the ground.
  • It prevents weeds from entering the raised beds from below: If there are dormant weed seeds on the concrete, you can prevent them from competing with your elevated plants by lining the concrete.
  • It prevents toxic chemicals in treated frames from entering the substrate: If the frame of your bed is coated or treated with toxic chemicals, you should line the frame so that your plants can be safe.

When you get the landscape fabric, you should line both the frame (vertical) and ground (horizontal) so that your plants and their substrate can be safe from foreign factors.

– Add Soil and Compost

It is time to pour in your soil and compost into the lined bed. Make sure that the substrate you use is new and well-drained. If you are using topsoil or soil from your garden, ensure that you bake it for some minutes to eliminate microbes and weed seeds in it before you use it. 

Add Soil and Compost

Pour in the substrate but leave 1-2 inches of space above so that water does not spill over when you are watering your plants. Continue to add more soil until you get your desired substrate height.

– Plant Your Crops

You want to build raised beds because of your crops, right? It is time to plant the crops. You can start your elevated garden with seeds or vegetative parts of plants, such as cuttings. You can also plant the seedlings of your preferred plants. 

Plant Your Crops

Remember to check the spacing and other requirements of the plants. Only plant crops that you are skilled at growing in your elevated garden so that you can easily take care of them.

– Clean the Concrete Regularly 

When watering your plants, you may sometimes notice that water spills out of bed, especially if you are using a lumber frame.

This water usually contains nutrients and dirt, so it can stain the concrete around your elevated garden.

Use your mop, brush, and other cleaning tools to regularly clean the concrete so that your garden can always look clean and beautiful.

– Add Helpers to the Bed

Helpers are beneficial organisms that can ease your gardening journey. These organisms are completely safe for your plants, so you have nothing to worry about.

Some gardening helpers that you can introduce to your bed are:

  • Earthworms: They help to aerate the soil as well as provide extra nutrients to your plants. They also help remove dead roots from your plants.
  • Nitrogen-fixing bacteria: These bacteria help to add extra nitrogen to the substrate. You can introduce them by planting a legume such as beans.
  • Predatory insects: Insects such as ladybugs help to control the aphid and spider mite population in your garden. You can get them from gardening stores near you.

– Regularly Check the Frame For Cracks and Holes

If you have wood raised gardens or metal raised gardens, you may sometimes notice cracks on the frame.

Do not wait an extra day before you patch or fill the cracks so that you can keep your plants safe. Leaving the cracks will just lead to more cracks and can lead to the wreckage of your bed.

– Regularly Enrich the Substrate

In a plain garden, some mobile nutrients can find their way to your plants because the plants are in the ground.

However, every nutrient in a raised bed garden must be provided by you because the substrate is not connected to the nutrient-rich soil below it.

This means that if you want your elevated crops to be as productive as they can, you’ll need to regularly fertilize your plants.

How To Maintain the Highest Quality While Building Raised Garden Bed?

Before building raised garden beds on concrete, you should consider the location of the bed. You should also consider the size and requirements of your plants as well as the soil qualities. Remember to always check the pH of the soil and ensure that it is suitable for your plants.

– The Location

Building a raised garden is easy. The problem only comes when your plants are not as productive as you want them to be. If the substrate is nutritious, but your plants are not growing as quickly as they should nor producing as many fruits as they can, the problem might be the location. You want to choose a location with suitable light, humidity, and temperature for your plants.

Before building an elevated garden, make sure that the location you choose to use is ideal or suitable for the plants is your choice. Make sure that the place gets at least six hours of daily sun. If possible, plant a potted garden in that spot for a growing season and check that your plants are going well before you build the bed.

– Your Plants of Choice

The plants that you choose to grow also matter.

Your Plants of Choice

Some factors worth considering are:

  • Root depth: Plants that grow long roots or tuber-growing plants are not suitable for elevated gardens because they might damage the frame or concrete below.
  • Spacing requirements: If your plants need a lot of space between them, you may end up not growing as many plants as you want to. Grow plants that do not mind sharing limited space with others.

Consider these factors first before planting the crop in the elevated garden. Also, note that you’ll need to regularly fertilize and water plants with little space between them so that their roots do not compete for anything.

– Soil and pH

You should always remember that concrete is alkaline. This means that if the ground below gets cracked or your plant roots can penetrate the concrete, there’s a high chance that the pH level of your substrate might change.

To prevent your plants from growing in a substrate with very high pH levels (i.e., alkaline), you should regularly check the pH of the substrate.

If the pH is higher than what your plants require, amend the substrate. You should make use of a slightly-acidic or neutral soil mix when growing plants with such requirements and ensure that the pH never gets too high.


We are confident that by now, you have all the information that you need on how to build a raised bed on concrete.

Before you start building, remember these key takeaways that will help you during the process:

  • Try to plant crops with shallow roots so that they do not destroy the concrete block.
  • Your planter box on concrete can have wooden, metal, or any solid material as its frame.
  • Perform regular checks on the frame and make sure that there are no holes or cracks.
  • Use nutritious and well-drained garden soil for your elevated crops.
  • To build a raised garden bed over concrete slabs, make use of liners so that your plants can be safe from toxic chemicals in the frame.

Gardening on pavement and concrete will surely be easy for you. Just perform the regular checks, and you are good to go.

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