The Top 5 Things You Need to Know Before Building A Raised Garden Bed

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Raised garden beds are a practical and aesthetically-pleasing way to grow your herbs, vegetables, and flowers. But there are some raised bed details you should consider that you probably didn’t think about!

Here, I answer 5 of the most commonly asked questions about raised garden beds.

So What Are Raised Garden Beds?

Just what it sounds like, a “raised garden bed” or “raised bed garden” is a bed of soil that is elevated above the existing soil level. This can be a mounded shape (like “hugelkultur”) or the most traditional type in which the garden bed is boxed in with wooden frames.

Raised garden beds can be used for vegetables, herbs, or flowers. You will often see raised garden beds for vegetables since raised bed soil can be easily amended to cater to the plants’ needs and the soil is typically less compact.

What is the Advantage of a Raised Bed Garden?

There are many advantages to using raised bed gardens when compared to in-ground gardens.

Raised beds are useful for:

Creating a better soil ecosystem of amended soil when the surrounding soil is poor quality or full of rocks or tree roots.
Keeping out common weeds that may be growing in the surrounding area.
Easier to weed because of less compact soil and not needing to bend down as low to tend to the garden.
Relieving back and knee problems since it is, well…raised.
Creating well-draining soil with less compaction so that roots can grow deeper and stronger.

Now, that we’ve established what raised garden beds are and what’s so great about them…

Here are the things you need to know before building your raised bed garden:

#1. How Deep Should A Raised Garden Be?

Remember that the taller the raised bed you build, the more soil you will have to fill it with. Soil, especially if bought in bags (instead of bulk), can be expensive!

The average depth of a raised garden bed is about 8 to 12 inches. If you are starting a raised vegetable garden from scratch, aim for a deeper garden bed of about 10 to 12 inches.

#2. What Kind of Wood Should I Use for Raised Beds?

Cedar is the best type of wood for building a raised bed garden. Cedar is naturally rot resistant and long lasting. So is juniper and pine.

Avoid chemically-treated wood if you plan to grow vegetables or herbs, since these chemicals can seep into your edible plants.

Environmentally-Friendly Option: To ensure that the wood you buy is not contributing to cutting down old growth forests, look for wood that has been FSC certified. The Forest Stewardship Council (FSC) certifies and labels wood that comes from sustainably managed forests.

#3. What Do I Put on the Bottom of a Raised Garden Bed?

First of all, if you have Bermuda grass or another aggressive type of grass, I recommend removing it from under your raised bed. If you have other less-aggressive grass, lay down cardboard (or several layers of newspaper) first on top of the grass and then put the raised bed’s soil on top of that. Do this in the Fall so that the grass below the cardboard and raised bed will die off over the winter.

Using this layer of cardboard on the bottom of your raised garden bed helps to prevent weeds from growing through and even acts as compost. This adds organic material to the soil, promoting healthier soils that the roots of your plants can grow into.

By avoiding plastic weed barrier fabric, you are actually creating a more sustainable environment for your garden. A completely enclosed raised garden with impenetrable weed barrier fabric on the bottom requires you to amend and feed the soil because it is a closed system. The cardboard method, however, connects to the existing environment below it and is therefore a more sustainable gardening option.

You may also consider adding a layer of grass clippings, leaves and other organic material before you put down the layer of cardboard to also turn into compost for even healthier raised bed soil.

#4. Where Should Raised Garden Beds be Placed?

Place your garden in a sunny location in your backyard or side yard. You can plan ahead by noting throughout the day the locations in your yard that get at least six to eight hours of sun.

Even more sunlight, like ten to twelve hours would be ideal too.

Note: You may need to be careful that your raised bed is not too close to a fence or even a covered patio that can shade out the garden after a certain hour of the day.

If you don’t have enough sunlight in your yard, you can still put in a raised garden bed with plants that grow well in the shade.

Avoid slopes and areas with clay soil or poor drainage. You don’t want your garden to retain too much water, especially after a rain.

^ This is my raised garden bed (3′ x 6′).

#5. What Size Should A Raised Garden Be?

It is important to consider the width of a raised bed garden, because you will need to access the bed from both sides without stepping in the soil.

The typical size of a raised garden bed is 3 to 4 feet wide and 6 to 8 feet long. Keep in mind that the longer your raised bed, the further you will have to walk to get to the other side of it.

For reference, mine are 3 feet by 6 feet, and I think they are the perfect size.

If you have multiple beds, keep 2 feet distance between them so you can easily move and work between the raised beds.