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  • Naomi Stephens | Permaculture Designer

Raised Beds on Concrete: A Step-by-Step

Updated: Apr 27


Do you have a concrete patio or driveway you're unsure what to do with? You could leave it as is, but if you want to add some life and color to your outdoor space, consider creating raised beds on concrete.


Raised beds on concrete are a great way to grow food in a small space. In this blog article, I'll cover five steps to increasing raised beds and frequently asked questions.



In this article:



Benefits of Raised Bed Gardening on Concrete


Raised bed gardens on concrete offer several benefits that make them an ideal choice for gardening in small spaces.


  • Firstly, they allow for better drainage, which can be especially important when gardening on concrete.

  • When gardening on concrete, raised beds are particularly helpful as they allow for the creation of a suitable growing environment. Since concrete is not a good growing medium, gardeners can add high-quality soil, compost, and other necessary amendments to the raised beds. This helps to create a fertile and nutrient-rich soil that supports healthy plant growth.

  • Thirdly, raised bed gardens on concrete can be easier to maintain than traditional gardens, as they require less weeding and can be accessed more easily.

  • Finally, raised bed gardens on concrete can be a great way to add life and color to outdoor spaces, making them a popular choice for urban gardeners looking to create a green oasis in their city.




Step 1: Choose Your Plants


When choosing plants for your garden, consider the amount of sunlight and water they will need. If you are gardening on concrete, you may not have a lot of space for large plants.


Instead, opt for smaller varieties that can be grown in containers. Some good choices for container gardens include herbs, succulents, and dwarf vegetables.


You should also consider the maintenance required for each type of plant. For example, herbs generally require less watering than other types of plants.


The best edible plants for raised gardening beds are:


- lettuce

- spinach

- kale

- chard

- radishes

- carrots

- beets

- herbs (basil, oregano, thyme, mint)


These are the best edible plants for raised beds on concrete because they are all small and require little maintenance.


Succulents also have relatively low maintenance, but they will need more sun than most other types of plants. Once you have selected the plants for your garden, it is time to move on to step two: preparing the concrete.


Step 2: Preparing the Concrete


Before starting raised bed gardening on concrete, you must prepare the concrete surface. First, remove any loose debris or dirt from the surface.


Next, clean the concrete with a garden hose or pressure washer. If any cracks or holes exist, fill them with a concrete patching compound such as this one.


Once the surface is clean and smooth, you can start building your raised bed garden.


Step 3: Choosing your raised beds for concrete


The best-raised beds for concrete are sturdy and made of weather-resistant materials like cedar, metal, or recycled plastic.



Cedar Raised Beds


Cedar is popular for raised garden beds because it is naturally rot-resistant and durable. This makes it an ideal material for raised garden beds placed directly on concrete, as it will not break down over time. Cedar also has a beautiful grain pattern and natural coloration that can add character to your outdoor space.


However, cedar can be more expensive than other materials, such as pressure-treated lumber. And because it is a softwood, it is also more prone to damage from impact or pets. Overall, cedar is a good choice for raised garden beds on concrete.


There are a few highly recommended cedar raised beds that are available on Amazon:


Boldly Growing has a 4x4 Cedar rot-resistant raised bed, available as a single or double raised bed. This product out-competes most on the market in its range because of the following:

  • It's a great raised bed for gardening edible varieties because 11" height is sufficient for adequate root growth.

  • It has a better build system, meaning you can build it in just three simple steps. The holes are pre-drilled, making your life so much easier. Most people comment that it takes them less than 20 minutes to build.

  • Being around kids or pets is safe as they ensure the boards are adequately sanded and without splinters.

  • They use raw, untreated cedar, meaning no toxic materials will leach into your garden bed.

  • There is attention to detail in the grooves and carpentry, which makes them look stylish in your garden.

  • They provide a one-year warranty.


Boldy Growing Raised Bed has very positive reviews. People note that it survives harsh weather such as snow, rain, and wind without any signs of cracks or strain.


Click on the slide show below.



At the time of writing, this product cost $99 for a 4x4 on Amazon





Plastic raised beds


There are several reasons why plastic is often chosen as the material for raised beds on concrete. One of the main advantages of plastic is its durability. Unlike wood, which can rot or be damaged by termites, plastic beds will last many years with minimal maintenance.


In addition, plastic is much lighter than wood, making it easier to move and position. Another advantage of plastic is that it doesn't require special treatment or sealing, as concrete can sometimes. Finally, plastic beds are often much less expensive than wood or metal.


However, there are also some disadvantages to using plastic for raised beds. One of the main drawbacks is that plastic can get very hot in direct sunlight, damaging plants. In addition, plastic is not as strong as other materials and can be easily damaged if not handled carefully. Despite these disadvantages, plastic remains a popular choice for many gardeners due to its many advantages.


Victory 8 Garden has 4x4 highly convenient plastic raised beds, which saves a lot of hassle and is cheaper than other options. They also have a wide range of sizes. It's a highly recommended option for a plastic raised bed because:


  • It has no DIY assembly

  • It's a good depth for growing root vegetables at 11.5."

  • It's made of Aeroflow and is specifically designed to allow airflow.


It's currently more popular than the above cedar raised bed because it's a reliably easy product to use and is both durable and weather-resistant. It's also beneficial for people who only have a small, limited space to grow, for example, on their balcony.



At the time of writing, it's currently on sale at $49.97; it was initially listed at $79.95







Metal raised beds


There are many benefits to using metal raised beds on concrete. For one, metal is a durable material that lasts many years. It's also easy to clean and maintain. Additionally, metal raised beds can help to control the temperature of the soil, which is essential in hot climates.


However, there are also some drawbacks to using metal raised beds on concrete. One downside is that they can be pretty expensive. Additionally, they can get very hot in direct sunlight, damaging delicate plants.


Land Guard has a best-selling, highly reviewed 4×2×1ft,7.14Cu metal raised bed. It's an excellent choice for raised beds on concrete because it's easy to set up, has an open base, and is thicker than your average metal raised bed, reaching 1.56mm thick.


It comes with extra nuts and bolts. Many people comment that it is pretty sturdy and it allows for creativity. For example, if you buy two sizes, you can mix and match how you put them together.


However, as the instructions warn, it does have sharp edges, so if you have kids around, be extra careful or perhaps consider a wooden or plastic raised bed.



At the time of writing, it's currently on sale at $59.99; it was initially listed at $79.99





Step 4: Adding Drainage, Soil and Plants


Start filling up your raised bed by adding a filler material, such as gravel, sand, or soil, which can be added to the bottom of the raised bed to help drainage. You can also add a layer of fabric or plastic lining to the bottom of the bed to help prevent weeds from growing through the concrete. It will also stop the liquid from leaching onto the concrete. Whatever you choose, make sure it is something that will not block the drainage holes in your raised bed.


Now that your drainage is set up, it's time to add soil and plants! If you are using a pre-made mix, follow the instructions on the bag. If you make your mix, start with a layer of organic matter such as compost or leaves. Add a layer of topsoil, and then mix in some sand or other amendments to improve drainage. Once your bed is filled with soil, it's time to start planting.


If you're growing vegetables, choose varieties well-suited to your climate and soil type. According to their mature size, space plants give them enough room to spread their roots. With some care and attention, your raised bed garden will soon burst with life!





Step 5: Caring for Your Raised Bed Garden


Assuming you have followed all the steps up to this point, you should now have a beautiful raised garden bed full of healthy plants. But how do you care for a raised garden on concrete? The key is to ensure the bed stays moist but not too wet. Water in the morning so the leaves have time to dry off before nightfall.


If it is especially hot or windy, you may need to water more than once daily. You can use a sprinkler attachment hose or install a drip irrigation system. When it comes to fertilizing, less is more. Too much fertilizer can burn your plants. Apply a fertilizer made for vegetables once a month, or follow the directions on the package.


As your plants grow, you may need to stake them or add supports to keep them from toppling over. Just be careful not to damage the roots when you are adding supports. With a bit of care, your raised garden on concrete will provide you with fresh vegetables all season long!


FAQ'S


Can you use galvanized steel to build raised beds?


You can build raised beds out of wood, stone, or concrete blocks; one material you may not have considered is galvanized steel. Galvanized steel is highly durable and lasts many years with proper care. It's also relatively inexpensive and easy to find. One downside of using galvanized steel for raised beds is that it can be challenging to cut and shape. However, many hardware stores now carry pre-cut panels that make it much easier to get started.


How do I create drainage in raised beds?


Drainage is an essential consideration for raised garden beds. Poor drainage can lead to plant roots sitting in water, root rot, and other problems. There are a few different ways to improve drainage in raised beds. One is to add a layer of coarse gravel to the bottom of the bed before adding soil to help the water drain faster.


Another is to ensure that the bed is elevated at least six inches off the ground, which will help water drain away from the roots. Finally, choosing a soil mix that includes perlite or sand is essential, as it will help water drain more quickly. Following these tips ensures that your raised garden beds have good drainage and healthy plants.


Can a raised bed on concrete cause discoloration on the concrete surface?


Yes, a raised bed on concrete can cause discoloration. If the area is not properly sealed or waterproofed, water can seep through the concrete and into the soil of the raised bed, staining or discoloring the concrete surface.



How to prevent raised beds from staining the concrete

You'll need to take some preventative measures to prevent raised beds from staining the concrete. First, line the bottom of the bed with a base layer of landscape fabric. This will help to create a barrier between the soil and the concrete. You can also use a waterproof protective material such as a plastic liner or heavy-duty pond liner to create a barrier between the soil in the raised bed and the concrete surface. This will help keep water from seeping into the bed's soil and causing discoloration on the concrete.



How to prevent water runoff and rust in raised beds on concrete


Many gardeners who have raised beds made from concrete blocks or brick find that, over time, the bed frames start to leave behind a tell-tale rusty-red stain on the patio or walkway. While this may not be a severe problem, it can be unsightly. Fortunately, you can take a few simple steps to prevent rust stains from occurring in the first place.


First, make sure that your raised bed has a sound drainage system. Excess moisture is one of the leading causes of rust, so it's essential to allow excess water to drain away from the bed.


Second, a sealant layer should be applied to the inside and outside of the bed frame. This will create a barrier that will help to prevent rust from forming.


Finally, if you notice any rust stains starting to form, scrub them away with a stiff brush and soapy water. With a little effort, you can keep your raised bed looking new for years.


What type of compost mixture should I use in my raised garden bed?


The type of compost you use can significantly impact the health of your plants in raised garden beds. A good rule of thumb is to use a mix of two parts: green material and one part brown material. Green materials, including grass clippings and kitchen scraps, are rich in nitrogen.


Brown materials are rich in carbon and include dead leaves and wood chips. Together, these two types of material will provide your plants with the nutrients they need to thrive.


In addition, be sure to use a gardening fork or tiller to mix the compost thoroughly before adding it to your raised garden bed. By choosing the right compost mixture, you can ensure that your plants will have everything they need to grow strong and healthy.


Is it safe to grow a raised bed on concrete?


While concrete may seem unlikely for a garden bed, it can be an excellent option for urban gardeners. Concrete is durable and low-maintenance, and it can provide a level surface for planting. In addition, concrete can help to moderate soil temperatures, making it ideal for hot climates. However, there are a few things to remember when growing concrete plants.


First, ensure the concrete is clean and free of any chemicals that could harm plants.


Second, consider using a liner to prevent soil from leaching into the concrete.


Finally, ensure adequate drainage by drilling holes or installing a drain pipe. With some care, concrete can be an excellent option for growing healthy plants.


How deep should a raised bed on concrete be?


The answer depends on the type of plants you want to grow. For most vegetables, a depth of 12-18 inches is ideal. This will provide enough space for roots to spread out and allow the plant to reach its full potential.


If you plan on growing taller plants, such as tomatoes or corn, you'll need a deeper bed of at least 24 inches. This will give the roots plenty of room to grow and support the plant's weight. No matter what type of plants you're growing, make sure the bed is at least 6 inches high to prevent weeds and pests from invading your garden.


Can you put a raised bed on a balcony?


A raised garden bed is the perfect solution for anyone who wants to grow plants but doesn't have a lot of space. They can be placed on a balcony, deck, or small backyard. Raised garden beds are easy to construct and can be customized to fit any space.


You can choose the material, size, and shape of your raised garden bed. Additionally, raised garden beds help improve drainage and prevent soil erosion.


If you consider adding a raised garden bed to your home, check with local zoning regulations first. With some planning, you can enjoy the benefits of fresh produce without taking up a lot of space.


Are raised beds better than planting on the ground?


Raised beds have many advantages over traditional gardening techniques. Plants can grow more efficiently because the soil in raised beds is not compacted. In addition, raised beds offer better drainage and aeration, which can lead to healthier plants.


Raised beds also make it easier to control the quality of the soil, as well as the temperature and moisture levels. As a result, raised beds can be an excellent option for gardeners who want to achieve optimum growing conditions for their plants.


Another benefit of raised beds is that they can be placed in areas that are otherwise difficult to garden, such as steep slopes or areas with poor drainage. In addition, raised beds can create barriers between different types of plants, which can help reduce competition for resources. As a result, raised beds offer several benefits that make them an ideal choice for gardeners who want to get the most out of their gardening efforts.


 

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