The natural contour of your land can be quite a challenge when you want to place a raised vegetable garden or a raised flower bed. There are a few different methods in order for this to work out well, depending on what you are planting in your raised bed and how you want it to look as well. Some methods will last much longer too, when you are enlisting raised bed gardening on a slope.
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Can I Just Plant on The Natural Slope?
As you well know, plants that grow in forests or in the wild open fields aren’t always on level ground and they seem to do well, but it also depends on how severe the slope is. The higher side of your garden bed will dry out much quicker and the lower side of your garden bed will most likely be too wet and kill your vegetables or plants.
When you water your sloped garden bed, the water will run down to the bottom of the slope and all the nutrients in the soil that you’ve worked so hard to perfect will also wash downwards with it. Without some type of retaining walls, your soil would erode and run down the slope as well. So just trying to plant directly on the hillside on the ground is not a very good idea because all of your hard work and expenses will likely be lost, especially in hard rain.
What Are The Advantages of Raised Bed Gardening on a Hillside?
Raised bed gardening has some distinct advantages over a traditional vegetable garden with rows in it or separate flower beds for shrubs, trees, and any type of flowering plants. You get better drainage if the bed is raised because there is a deeper amount of fertile loose soil for the water to irrigate plants’ roots deeply. Deeper roots mean more sturdy plants in the long run as well and better health for your plants.
Raised beds give you higher yields of fruits and vegetables or more robust blooms on your flowering plants and ornamental plants because you have added some compost or amendments to the soil. You can also grow more plants in the same space because you have no rows between plants.
You will see that you have an expanded growing season because of the better drainage that keeps the soil warmer in spring planting. In the wet seasons, the soil drains more quickly to allow you to proceed with planting your garden faster.
Raised garden beds are much better on your back as you don’t need to stoop so far down to tend to them. Since these types of beds are generally planted intensively, the lush growth shades the small amount of ground where weeds could possibly grow, so it takes very little weeding.
Raised beds on a slope also help to prevent soil erosion in your lawn and you can style them in many different ways. Another advantage is that if you have poorly draining soil naturally and can’t usually grow much–you won’t have to worry about it because you will be using your own growing medium of choice in the bed.
Related: The Many Benefits of Raised Bed Gardening
Planning Your Raised Garden Bed
For best results, your raised garden bed on a hillside should be level. You should plan it to be a rectangle where the long sides of it run lengthwise across the hill instead of from the top to the bottom of the hillside. This will save you a lot of time and expense by purchasing extra soil and materials that act as retaining walls.
For most applications, lumber is the material of choice for the retaining sides of a raised garden bed. If you are planting vegetables, don’t use pressure-treated wood or repurpose old railroad ties as the chemicals on them can leach into the ground and enter into your vegetables. Instead, choose regular lumber and treat it yourself with safe, non-toxic products to make it last longer.
Related: Douglas Fir Raised Bed Garden
What is a Good Size for The Bed?
A good size for all garden beds is no wider than 4 feet on the short end of the rectangle. This allows you to reach to the middle from each side of the bed to pick vegetables or cut flowers easily. The length is up to you, but it’s best to make several beds instead of one that is very long.
Most plants do pretty well with 6 inches of quality soil, but 1 foot is actually better to encourage deep root growth. If you plan on a 4 foot wide by 8 foot long raised bed, it will make your job much easier because these are pretty standard measurements for your lumber, so it requires less cutting.
How to Build a Raised Bed on a Hillside
To make a raised garden bed that is 4 feet wide by 8 feet long and 1 foot deep on the more shallow end, you will need these supplies. 6-8ft long 2 X 6 boards and cut two in half. You will also need 2 more 2 X 6 boards that are 8 feet long and either nails or screws as well as a level. Depending on how deep your slope is, you will need some concrete pads to support the lower end. For your tools, you will need a saw, a level, a hammer, and a drill if you are using screws.
The first step in your raised garden bed is to make the 4 foot by 8-foot exterior. You simply attach the cut in half boards for the short ends to two of the 2 x 6 boards with nails or screws. Hint: the short ends go inside of the long ends to make a rectangle.
Put the box on the ground where you want your bed to be with the long side running horizontally across the slope. Put your level on one short end of the downhill side of your box and lift it until the bubble is in the middle of the level. Support this area with concrete pads. Place your level on the 8-foot long board on the downhill side of your box and level it in the same manner, then support it with concrete blocks.
At each of the four corners of your box stand up a 2 x 6 and measure it so it will be 6 inches taller than the box, then add 6 inches to that measurement and cut the board to size. Cut a pointed end on one end of the wood and use a hammer to drive it into the ground about 6 inches at the corner of the box. Repeat this step for the other 3 corners of the box to hold it in place and give it support. Add two more of these vertical supports at the center of each 8-foot long side as well. Attach each vertical support to the box with nails or screws.
Add your top layer of 2 x 6 boards by attaching them with nails or screws onto the inside of your vertical supports to create a 1 foot deep raised bed on the top of the hill on the long side and the bottom side will be deeper depending on how steep the slope is.
You are Ready To Fill it And Plant
Now you only need to fill your raised bed box with the soil of your choice and plant your vegetables or your ornamentals in it. A garden mix is usually readily available or you may choose to use topsoil for ornamentals.
Final Thoughts
Lumber for your raised garden box is usually the product of choice for a vegetable garden to reduce your prices in the creation. If you are planting ornamentals and flowers though, you may decide to just make a box out of landscaping stones and make sure each of the four sides is level to be more aesthetically pleasing to the eye.