Shipyards are not created equal. Some are beautifully flat and easy to work with, while others can stand on an inclined surface that either goes up or down. Without major terraforming work, you are no longer working with the landscape you have. Fortunately, building a raised bed on a hillside is an option, and there are several ways to do it!
Different variations may be required depending on how steep the slope you want to place your raised beds. You have to dig and level a bit no matter what you do, but the rewards will be well worth it.
So let's cover all of the important things you need to know in order to build your raised beds on a sloping area. No matter what your landscape is like, gardening is possible and you will love being able to replant your garden every spring!
Do raised beds have to be flat?
A homemade version of a terrace garden. Raised beds would be even better. Source: hardworking
From a technical point of view, a raised bed doesn't necessarily have to be level. After all, plants grow naturally on slopes! But a level raised bed can help with a lot of different things.
Watering is easier in a level garden bed. Applying water to the slope means the top will dry out more than the bottom of the slope. You want your bed to have an even distribution of moisture from the floor, so a level bed is best for this.
Likewise, nutrients dissolved in the water flow to the lowest point. Level beds will ensure the even distribution of fertilizers and other changes that you add to your soil.
When rain hits an uneven raised bed, another thing can be unevenly distributed: your growing medium itself. Failure to level your beds can create serious erosion problems.
After all, it's much easier to work on a flat surface. Gardening on the hillside can be a challenge at the best of times. So if you have the opportunity to balance things out, take it on! Your raised bed will perform better overall.
Reinforcement of a steep slope
If your hill is a steep slope near where you want your beds to be, it can seem daunting to get things moving. As the water flows downhill, carrying dirt and debris with it, erosion can be a major factor on a steeply sloping surface. Reinforcing your steeper slopes can protect your beds from damage and protect the rest of your garden from flooding.
The easiest method of reinforcement is to build retaining walls or reinforce fences to hold back the slope. This should be done at a time when rain is unlikely to interrupt your work, as this way you won't be at risk of erosion during half of your project!
You'll need to cut out the side of the mound to create a level, tiered position for your raised beds. Leave enough space for the raised bed and the reinforcement wall provided, as well as additional space if you want to access the side of the bed that is closest to the reinforcement. You will likely need to remove quite a bit of soil to get a level surface.
Once the soil is out of the way, you may need to remove a little more soil to add level sand and press it down to make a good base for your wall. This is especially true if you're building a concrete wall, as you don't want it to sink into the ground below! Take the time to make sure it is on a steady and secure footing now or you will be rebuilding it later.
After the ground is stable, it's time to start building your wall. Both concrete block and wood are options, depending on the steepness of your variety. A block of concrete should be used on a very steep incline, while wood may be used on a shallower incline.
A good concrete retaining wall can easily be 24 to 28 inches thick to ensure it can support the weight of the mound behind. Typically, these walls are made up of two layers: one that slopes inward toward the slope and a secondary wall that acts as a frontal surface that you will see. Between the inner wall and the slope, you need to add some gravel to allow excess water to drain and stabilize the soil.
Wooden retaining walls are often much thinner, but usually have a moisture barrier right against the ground, then a heavily reinforced fence panel against it. Often times, the fence panel has runners that also extend into the upper slope to ensure that the fence stays stationary. Reinforcing bars or heavy wooden posts provide even more stability.
Take the time to plan your retaining wall in advance and make sure there is plenty of space between it and your future garden space. Building a retaining wall can open up a lot of space for your future garden!
A raised bed can be built separately from or as part of a retaining wall. Source: bluekdesign
A terraced garden style can be done with or without raised beds. However, for best results, adding some raised structure can really improve your environment.
From a technical point of view, these multi-storey plots are another variant of high gardens. After all, all you are doing is leveling your yard and walking stairs for maximum work area. Something like this can be incredibly effective and indispensable when it comes to steeply sloping surfaces!
With a terraced garden, you definitely want to build sturdy retaining walls to prevent erosion. Something on the weaker side can cause a lot of soil to leak around the edges. This will gradually reduce the amount of good soil you have in your upper levels and can overflow the lower levels. So it's important to start right.
Building individual raised beds that will store the majority of your soil will avoid the erosion problems associated with patio gardens. You can even use the raised beds in conjunction with your patio to create a great, elegant space.
Gardening on a shallow grade
A gently sloping surface is much easier to work with and requires much less soil to move. For a vegetable garden in a location like this, you just need to level out the sloping surface a little before starting construction.
Make sure the surface for your future beds is level and pressed in place if you want it to be a little more compact and that everything is out of the way. Then it's time to build your beds!
Steel raised beds
A galvanized steel garden bed, such as the one sold through the Epic Gardening Store, is a great choice for construction. The construction of this bed style is incredibly easy as it is ready to use out of the box. Create the configuration you want when using one of the 8-in-1 or 6-in-1 beds by using the screws provided to hold it together in the shape you want. The fixed size bed pieces are also easy to assemble with screws.
Once your bed is assembled you need to make sure that the bottom of the frame is flush with the floor and the top is level. If you have made your preparations in advance, this is easy. Otherwise, remove small amounts of soil to level the sides of your bed.
If you're having issues with moles or gophers, put a hardware sheet under your bed to keep them from digging up your property. Double check the level to make sure your bed is not tipping downhill. Then fill in the potting soil of your choice and you're ready to grow!
One final point to consider with this type of bed: while the planting medium should keep your bed from moving, on a steeply sloping surface, you may want to confirm that the bed will not be able to slide forward due to the pressure of the hill. Stable posts made of reinforcement or wood can help. Drive the stakes to the inside of the bed to secure it in place. Wood deteriorates over time when covered with moist potting soil. Therefore, using rebar or other metal piles in general is a better option to use for many years to come.
Raised beds made of wood
The corner posts can serve as stakes to hold the raised bed in place. Source: osiristhe
Wooden beds on the hillside work well too. This garden style is more of a custom order than an out-of-the-box project, but it's easy to source wood and screws to assemble.
As with galvanized garden beds, make sure your bed isn't sloping or sitting at an angle. Level the floor in advance where your bed will be.
Most wooden beds are simply a box made of cut boards. Cedar is one of the preferred types of wood for this architectural style because of its durability, but you can opt for Douglas fir or other woods as well. Avoid pine trees as they will disintegrate quickly when wet. Gardens are always damp!
I prefer 2 x 6 lumber for the sides of my garden bed, but you can opt for other sizes depending on the design. The advantage of a 2 x 6 board size is that two boards stacked on top of each other are a foot high. Therefore, it is easy to plan the height you want and buy wood. Most people prefer raised beds with sides that are at least 30 cm deep, and these parts work well for that!
4 x 4 posts work well as reinforcement corners. If you want to anchor your bed securely in place, you can make the corner posts about 30cm longer than necessary for the height of your side walls and bury the extra 30cm underground at each corner. This ensures that the frame will not move or shift from its position.
Once your box is finished building, put it in and check the level. Adjust the placement of the bed sides to avoid tilting. As with metal beds, you can anchor your bed with stakes if necessary. Fill in your garden mix of your choice, plant it out and you will have a beautiful garden in no time!
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