Keyhole gardening vs raised bed gardening – discover which is best for you and your yard

Whether you want to make your garden more accessible or try a new way of growing, keyhole gardening and raised bed gardening are two excellent options. Raised bed gardening is widely known and used, but the lesser-known keyhole design is definitely worth considering, especially due to its sustainable credentials.

With global temperatures rising and periods of drought and extreme weather becoming more frequent, gardeners are looking at ways of making their gardens more viable. From reducing water consumption to recycling materials, even small changes, such as home composting, can make a difference.

When it comes to choosing between keyhole gardening and raised bed gardening, there are pros and cons for both. Read on to discover their benefits and disadvantages and how environmentally friendly each method is, to help you decide which growing system is best for your backyard.

What’s the difference between keyhole and raised bed gardening?

Put simply, both keyhole and raised bed gardens are structures created to grow above the ground at a height to suit the user.

However, keyhole gardening has its roots in permaculture and includes a central composting area that helps retain moisture and feeds the surrounding soil and its plants. Whereas raised beds do not and instead focus on improved drainage and soil control.

The advantages of keyhole gardening

Originating from sub-Saharan Africa, keyhole gardens are ideal if you garden in a dry climate or on poor soil.

Key to their circular design is a central basket or cage that is used for composting, which, when watered, irrigates and releases nutrients into the surrounding growing bed, rather than into the ground below.

This method is advantageous because not only does it reduce water consumption, which is beneficial for the environment and saves time, but it also encourages the practice of composting and provides a specific area for this if you do not have one already set up.

Furthermore, through feeding the soil naturally, keyhole gardening helps maintain soil health and reduces the need to use fertilizers.

Being able to be built to any height, keyhole gardens can also be made accessible for those with reduced mobility and the growing area can be kept out of reach of any inquisitive pets or pests.

Additionally, keyhole gardens can be constructed from almost any material, meaning that you can use up any building materials you might have lying around and keep costs low.

The disadvantages of keyhole gardening

Ideally, a keyhole garden should be a minimum of 6 feet across and 2 – 3 feet high for it to work as designed and perform well. With access being required from both within and around the circular structure, a space of 8 feet in diameter is needed, which may not suit those with a smaller yard or balcony.

Keyhole gardens, like raised beds, need to be constructed, but unlike raised beds, tend not to come in easy-to-put-together kits. With stones, bricks, or logs typically used to form the outer and inner ‘key’ walls, you will also need to construct the inner compost basket from wire mesh or chicken wire.

Although creating a good opportunity to reuse any materials you might have spare, keyhole gardens can look a bit untidy and even messy, which might not suit a minimalist garden design.

Another disadvantage of keyhole gardening is that, through the inclusion of a composting area, pests such as rats and other vermin may be encouraged. Not adding meat, fish and dairy and regularly turning the compost area may help prevent rats from taking up residency, but gloves should be worn and care should be taken if children are present.

Due to the potential aesthetic and pest issues, if you do want to install a keyhole garden, you might want to consider placing one out of view or further down the garden, where these issues might be less of a problem.

The advantages of raised bed gardening

Often used for wellness and community gardens, where inclusivity is all-important, raised beds can also be found in many front and back yards. Being constructed anywhere from 6 inches to 3 feet in height and almost any length and width, raised beds can be adapted for any garden and its users.

Raised beds can be made from materials including brick, treated timber, or from kits such as this ‘Raised Garden Bed 4 x 4 ft Planter Box available from Amazon. Raised beds can be quick to assemble, but can be expensive depending on the materials used.

Generally used to grow vegetables and flowers, raised beds can be filled with any type of soil or growing medium and can be modified for almost any type of growing. This makes it ideal for growing root crops such as carrots, Daucus carota, as there will be no stones in the soil that might cause them to fork.

Or they could be filled with an ericaceous soil for growing acid-loving plants like blueberries, Vaccinium. Also beneficial is that being raised off the ground avoids any compaction from footfall, which means aeration and drainage remain optimal.

Another advantage of raised beds is that they can be made to fit the space available, both large and small. If accessible from both sides, raised beds can be up to 3 feet in width, with the middle of the bed being reachable from either side.

Alternatively, shallow raised beds around 1.5 feet across are ideal for edging a small patio or even placing on a balcony, if structurally sound. Additionally, raised beds can be installed on any hard surface, which makes them ideal for school playgrounds, community spaces, or courtyards where the ground is not soil-based.

Furthermore, and depending on the design and materials used, raised beds can last many years and offer a tidier and more organized growing system than when compared to keyhole gardening.

Growing above the ground in either a raised bed or a keyhole garden also extends the growing season, as the soil warms up more quickly in the spring and can retain its heat for longer in the fall, meaning more vegetables and flowers for longer.

A final advantage of raised bed gardening is that the very much on-trend no-dig method can be followed, as through laying cardboard over the existing ground and adding soil and other organic matter to the desired height, the ground below is not disturbed or damaged through digging it over.

This Vego modular raised bed from the Gardening Know How shop is perfect for a smaller yard. It can be configured in six different ways and comes in a range of shades.

The disadvantages of raised bed gardening

Unfortunately, the soil in raised beds tends to dry out more quickly due to the improved drainage and exposure to drying winds, which makes them perhaps better suited to more temperate locations.

You can help reduce the soil from drying out by mulching the soil with organic matter or garden compost, which will help lock in the moisture and by installing an irrigation system such as this ‘MIXC 230FT Quick-Connect Drip Irrigation System Kit’ available from Amazon, which will water directly to the plants' roots.

Like a keyhole garden, raised beds, depending on the materials they are constructed from, are a semi-permanent structure. Thus, you will want to ensure you erect either of them in the right place the first time around, as moving them can be not only laborious but costly as well.

Over time, through settlement and natural erosion, the soil level in raised beds reduces, and from my experience managing therapeutic and community gardens consisting mainly of raised beds, is especially noticeable for newly constructed beds. To mitigate this, you can top up the raised beds with compost or other organic matter as required.

If all this talk about composting, saving water and permaculture has got you thinking about how you can make your garden more sustainable. Our specialist article on how to create an eco-friendly garden is full of inspiration and tips on where to get started.