Slopes and hills in your yard can make planting a vegetable garden challenging. Level ground is ideal for gardens, but sometimes the only suitable spot has a slope. Rather than trying to level the ground or build terraces, you can build raised garden beds on the slope. With a few simple construction techniques, you can create beautiful and highly functional raised garden beds on a sloping yard.
Benefits of a Raised Bed on a Slope
There are several advantages to building raised beds on a sloped site:
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Improved drainage and airflow compared to planting directly in the ground Excess water drains out the bottom of the raised bed rather than pooling,
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Warmer soil in the spring for an earlier start to the growing season. The sides of a raised bed collect and retain heat better.
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Reduced erosion issues. Containing the soil in a sturdy frame prevents it from washing downhill.
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More even moisture levels through the bed since the bottom can’t pool water.
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Easier to work in than an angled garden plot The raised bed brings the soil level up to a comfortable height
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Can act as terracing to make the slope more usable. Beds create flat planting surfaces across the slope.
Raised beds truly optimize growing conditions on slopes for the best results.
Should Raised Beds Be Level?
For functionality and ease of care, raised beds absolutely should be level. On a tilted bed, the higher end tends to dry out faster while the lower end stays wetter. Leveling the bed prevents these moisture issues.
Nutrients can also leach downwards on a tilted bed, robbing the upper section. A level bed evenly distributes nutrients and soil. Likewise, erosion is minimized with a level install.
Building on a slope takes a bit more work, but the effort to level the bed is worthwhile. Don’t just set a garden box on an angled yard. Lifting one end during construction ensures the finished bed is flat.
How to Build A Raised Bed on a Slope
Building a raised bed on flat ground is simple. On a slope, it takes a few extra steps to create a level structure. Here is a step-by-step guide:
Materials Needed
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2×6 boards (cedar or pine). Length depends on bed dimensions.
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2×4 boards for corner supports.
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3″ deck screws or nails.
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Garden soil mix.
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Landscape fabric (optional).
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Crushed gravel or stones (optional).
Tools Needed
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Circular saw or hand saw
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Drill for screws or hammer for nails
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Tape measure
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Shovel and garden rake
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4′ Level
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Wheelbarrow
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Work gloves and safety glasses
Instructions
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Layout the shape and location of your raised bed. Measure and mark the footprint.
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Remove grass or weeds from the layout area. Dig down several inches.
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Add crushed gravel or stones and level if drainage is a concern.
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Build bottom frame using 2×6 boards. Check corners for square and levels.
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Add vertical supports every 4′ around the inside edges of the frame.
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Attach second layer of 2×6 boards to create walls. Check for level.
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Fill bottom 2″ with gravel if desired. Add landscape fabric.
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Shovel garden soil into the raised bed. Pack down lightly. Top off until full.
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Install 2×4 boards around the top perimeter for a finished look.
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Consider anchoring the bed in place with rebar or wood stakes if on a steep slope.
The key points when building a raised bed on a hillside or slope are preparing a level base, checking for level frequently during construction, and anchoring the finished bed in place. Don’t just set down a garden box on the existing terrain. Lifting one end or adding vertical supports ensures your finished bed is nice and flat.
With a few simple adjustments to account for the slope, you can install durable and great looking raised garden beds. The end result is a highly productive growing space optimized for vegetables, flowers or herbs. Slopes need not stop you from enjoying fresh homegrown produce!
Tips for Building on Steep Slopes
On gentle slopes, standard square raised beds may be fine. But on steeper grades, additional precautions should be taken:
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Retaining walls may be necessary to prevent erosion around the beds. Pressure treated lumber or masonry can create stairs across the slope.
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Wider frames, at least 2×8 boards, provide more stability on inclines. Narrow beds can shift or tilt over time.
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Cross bracing along the lower frame helps strengthen the bed. Use scrap lumber to brace front-to-back and side-to-side.
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Anchor the bed well at the top of the slope. Drive long wooden stakes or rebar pins into the ground to keep the bed from sliding downhill.
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Add more vertical posts for support, especially toward the lower half of the bed where force increases.
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Consider building beds in a terraced design across the slope rather than directly down it for better stability.
With extra reinforcement, raised beds can be installed on even fairly extreme slopes. But for very steep grades, it may be best to create terraced spaces first before building the raised structures.
Material Options for Raised Beds on Hills
You have choices when it comes to the framing material for raised garden beds on a sloped yard:
Cedar – Naturally rot-resistant softwood. mid-range cost.
Pine – Untreated pine is cheaper but decays faster. Avoid treated.
Redwood – Excellent for outdoor use but expensive.
Landscape timbers – Budget-friendly but break down quicker.
Composite lumber – No rotting but can be pricey.
Galvanized steel – Sturdy and long-lasting but prone to rust.
Concrete blocks – Heavier but provide very stable walls.
Choose rot-resistant woods or galvanized steel for longest lifespan. Softer woods work but require replacing every 5-10 years as they deteriorate. Concrete block is heavy to work with but makes indestructible beds.
Raised Bed Style and Design
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Height – For easy reaching across, keep beds 3-4 feet wide. 12-18 inches high maximizes depth while allowing access.
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Shape – Square or rectangular beds are standard. Custom shapes also work if well supported.
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Size – Depends on space available and desired plantings. 4×8′ is a common dimension for vegetable gardens.
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Materials – Durable, rot-resistant woods are ideal. Galvanized steel also works well.
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Edges – Finish with trim boards for a polished look. Capstones or bricks can also frame the top.
Beds can be styled simply or with decorative details. Just ensure the construction is stable, especially on slopes. Focus on functionality first when installing beds on a grade.
With smart construction techniques like adding vertical supports and checking for level frequently, raised garden beds can be installed on practically any slope or hillside site. Put in the effort to create a flat, stable frame, and the end result will be a highly productive and great looking garden bed, even on challenging terrain. Don’t let slopes stop you from enjoying homegrown fruits and vegetables!
Step 4: Place the Raised Beds
Now that youve done the hard work of moving all that material around, its time to get your beds in the right spot. Place your beds where you want them to go. Use your speed square and your measuring tape to ensure you have right angles and that everything is lined up just the way you want it.
This step seems simple, but it usually takes our team a good bit of time to get each bed situated and all lined up. We usually measure the distance from different points of the raised bed to permanent objects like patios. We measure the distance from one raised bed to another. Then we double check all our measurements.
Its time to put the finishing touches on your bed installation by ensuring your beds are level with one another and adjusting as needed. Place a beam level between each and every bed, front to back and side to side, to see which sides need to move up and which need to move down.
You also want to check the levelness of each raised bed.
By this point, youve already done 85% of the leveling. Youre just tweaking sides and edges as needed so that when you look out over your garden, the tops of the raised beds are all level.
Step 1: Measure the Existing Slope
Install your rebar or stakes at the four corners of your cleared garden space. Use your measuring tape to make sure each corner is where it should be.
Wrap the string or twine around the four stakes to create a square along the perimeter of your garden.
Use the line level on every side of the perimeter to ensure the string is level. Youll need to raise the string in some corners and lower it in others. This is essentially creating a level plane that doesnt exist yet in your yard.
Once youve ensured your string is level all around, youre ready to measure the slope of your space. Start at the lowest point of your slope and measure the length from the top of the string to the ground.
Then, move to the highest part of your garden and measure from the top of the string to the ground.
To calculate your slope, all you have to do is take the difference between those two measurements. In other words, subtract the highest point from the lowest point. For example, if the lowest point measure 15 inches from top to bottom, and the highest point measures 3 inches, then youve got a difference of 12 inches.That means youre working with a 12-inch slope.
How to Install a Raised Bed on a Slope the Easy Way | Step by Step
FAQ
Can I put a raised bed on a slope?
You can construct raised beds on a slope, it is easier and less expensive if you can find a part of your yard that is somewhat level.
How to build a vegetable garden on a slope?
The best solution for hillsides is to plant your vegetables across the slope using contour rows, terraces, or raised beds. This not only makes it easier for you but also prevents problems with erosion.
Is it OK to plant a garden on a slope?
Slopes are very good for a garden as they remove the risk of water pooling. Which will reduce nutrient distribution and cause flooding. And result in the plants drowning. Leave it as is. As for your stumps, make sure to use plants that do not have a long taproot, strawberries, tomatoes, greenbeans that sort of thing.
Do raised beds need to be perfectly level?
In some cases, entire yards are sloped, which is great for flood management and scenic views but not necessarily for planting. This leads to a common question: do raised beds need to be level? The short answer is that raised garden beds do not necessarily need to be perfectly level.