Having a raised garden bed is great if you’re living in an apartment or rented property, or the soil around your house isn’t suitable for growing plants. However, you may have reservations about using this gardening technique to grow plants on your balcony, driveway, patio, or other similar places.
Raised garden beds do not have to be buried in the soil to grow plants. They need to have a solid bottom frame to stay on concrete, asphalt, wood, tiles, and other similar materials. However, they require good drainage to prevent root rot and other plant diseases.
Let’s break down why you don’t have to bury a raised garden bed. Also, you’ll learn what you need to make the most of a raised garden bed.
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Should You Bury a Raised Garden Bed?
Raised garden beds look great on your property, especially when you don’t have enough space for growing various plants. You may wonder whether it’s a good idea to bury them, though.
You do not have to bury a raised garden bed, especially on hardscapes such as concrete, asphalt, tiles, and wood. Solid bottom frames will work as long as there is sufficient drainage to prevent water from accumulating in the soil.
The beauty of raised garden beds is that you can keep them almost anywhere, as long as you ensure they receive enough sunlight and have a sound drainage system.
While water is an excellent resource for keeping your plants alive, too much of it in the soil can cause several issues.
It’s important to remember that roots, just like leaves, need oxygen to survive. Air is present in the soil in small pockets known as soil pores.
When the soil has too much water, it reduces the amount of oxygen the roots can access due to the absence of a proper drainage system.
Over time, excess moisture can cause plant diseases. Also, the root cells die due to a lack of oxygen, leading to the plant’s eventual death.
Factors To Consider When Installing a Raised Garden Bed
Suppose you have a driveway and want to start a vegetable garden or grow ornamental plants to beautify your property. In that case, a raised garden bed is a good idea.
However, it would help if you remembered the key factors to consider when installing a raised garden bed — namely, the drainage and dimensions.
When it comes to drainage, keeping the bottom open is beneficial. It allows excess water to flow, ensuring the soil doesn’t become waterlogged and suffocate the plants.
On the other hand, an open bottom frame increases the risk of the soil falling out from your garden bed, especially if it is an elevated bed. You want to avoid this as it reduces soil volume over time. Also, your plants’ precious nutrients, which they rely on to thrive, will seep out slowly along with the soil.
One way to overcome this problem is to use hardware cloth. I recommend the Amagabeli Hardware Cloth 48×100 1/2 Inch (link to Amazon). This item is pretty versatile, so if you have any left over after you use it for your garden bed, you can also make fences and the like from it.
When using hardware cloth, don’t keep it at the bottom of the raised garden bed. Make sure you leave some space from the foot of the bed.
Also, you should use landscape fabric to keep the soil in place. Layer it over the hardware cloth, and you’re good to go.
I like the Sunifier Weed Barrier Landscape Fabric (link to Amazon). Despite its name, it’s not just for keeping weeds away: I think it works pretty well to prevent excess drainage. Plus, its polyproplylene material ensures that you’re not harming the environment in any way.
If water keeps falling on your hardscape, it will leave a stain. There are two solutions to overcome this issue.
- One option is to use a power washer, which easily removes the water stain.
- You can also use a drip tray to collect the runaway water.
However, depending on how frequently you water your plants, you’ll likely have to drain them every so often anyway. And remember, some perennial weeds can still push through landscape fabric.
Asphalt and Concrete
As I mentioned, the drainage of the raised garden bed plays a crucial role in whether your plants thrive or not. If the garden bed drains water too quickly, your plant’s roots won’t be able to access the amount of water they need, causing them to die.
Fortunately, you don’t need to close off the bottom of the frame for asphalt and concrete flooring.
When it comes to wooden surfaces in the balcony, deck, or patio, drainage is crucial. Although these materials have likely gone through extensive treatment to prevent rot, it can still be a problem if their surfaces remain wet for a long time.
In this case, you’ll have to close off the bottom frame of the raised garden bed. However, make sure there are sufficient holes to allow water to seep out of the setup.
You should also use a drip tray to prevent water from falling on the wooden flooring. Empty the trays regularly to avoid the overflow of water.
See our guide to the 7 Best Wood Options For Raised Gardens (And 3 To Avoid).
Your raised garden bed’s dimensions determine what plants you can grow.
For example, root depth refers to how far the plant’s roots will go to find nutrition and water.
There are three types of root depth:
- shallow (12-18 inches or 30-45 centimeters)
- moderate (18-24 inches or 45-60 centimeters)
- deep (24 inches or 45 centimeters and above)
Generally, you’ll need a raised garden bed 12-18 inches (30-45 centimeters) high to grow vegetables. If space is scarce, you can go for a setup 8-12 inches (20-30 centimeters) tall.
If you’re wondering about the required root depth of specific fruits and vegetables, check out this study from the University of Nebraska – Lincoln Extension.
As wet soil is extremely heavy, you’ll also need to reinforce your raised garden bed with support structures. Luckily, you’ll only have to do so when the setup’s length is over 6 feet (1.8 meters) or more than 18 inches (45 centimeters) in height (source).
You don’t have to bury a raised garden bed for hardscapes like asphalt, concrete, tiles, and wood. However, you need to pay close attention to this setup’s dimensions and drainage system.
As long as you can manage to stop water from flooding the soil, you’ll be able to grow a plethora of plants and enjoy gardening.
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