Gardening: The benefits of raised beds
Raised beds will allow you to grow a wider variety of plants, tend your borders without bending, and provide extra seating. What’s not to like, says Adrienne Wild
You can grow almost any plant you like in raised beds from cut flowers, fruit and vegetables to roses and other prize shrubs. They are the perfect way to improve drainage issue, too, and they can also be filled with a variety of different types of topsoil, matched to the needs of the plants you want to grow. These can include fussy plants like alpines that require extra-sharp drainage and lime-hating, ericaceous plants such as rhododendrons and camellias.
Raised beds will also add an extra dimension to your garden and are especially useful for creating visual interest on a flat site. With very little effort, you can even turn an urban backyard or large expanses of paving into an ornamental garden that includes features such as a raised fishpond and fragrant borders filled with plants arranged within sniffing distance. In fact, your imagination is your only limitation!
Best of all, they are a great boon to vegetable growers, as the soil in a raised bed tends to drain well and warm up more quickly in spring, which allows you to plant earlier and enjoy a longer season. You’ll find them especially useful for growing root crops, such as carrots and parsnips, because they can be filled with a deep, fine soil, which will promote long, straight roots that are perfect for the show bench.
You will also be able to double the yield of your traditional row layout, by planting in staggered rows and interplanting to maximise the use of available space. For example, if you plant in triangular instead of square patterns, you should find room for at least 10% more plants in each bed.
When interplanting two or more crops together, always plant early-maturing varieties in between longer-season vegetables, so that when you harvest the first crop there is room for the late varieties to develop. Good neighbours are lettuce, alongside broccoli, peppers or tomatoes.
For best results, it’s always a good idea to pair shallowrooting vegetables with deep-rooted ones and if you select compact varieties, it will make things easier. Take care not to space your plants too tightly, though, as doing this can stress plants, making them more susceptible to diseases and pest attack – close enough so that
their leaves just touch and they shade the ground when fully mature is perfect.
To help reduce pest problems, you might also like to consider dedicating a raised bed to all plants belonging to the problematic cabbage family. This will allow you to net the entire bed to prevent cabbage root fly access and the cabbage white butterflies from laying their eggs on the leaves. You could also plant one entirely with carrots and corral them under a 60cm-tall barrier of Enviromesh to keep out the damaging carrot root fly.
Tall-growing climbers such as beans and peas can still be grown in raised beds, but will need to be located where they won’t shade lower-growing vegetables. Sprawling plants such as squash are best planted towards the edge of the beds, so that they don’t smother their neighbours.
To get those extra weeks of production, it’s important to site the beds in the sunniest part of the garden and away from frost pockets. You’ll gain as much as a four-week head start on the season if you keep the air around your early crops warm, by using mulches, cloches, plastic tunnels and horticultural fleece.
Squeezing in a few fast-maturing succession crops such as lettuce, kale and turnips will also allow you to stretch the season. Before planting the second crop, though, ensure that you feed the soil with seaweed fertilisers or well-rotted manure to keep it rich in nutrients.
Raised beds are easiest to maintain if they can be reached from all sides – 90-120cm is ideal – and a maximum length of 3m will save you time and the effort of having to keep walking too far around the beds to get to the least accessible parts of the garden.
The biggest benefit of not having to walk in among the plants to tend the plot is that you will avoid compacting the soil. Repeatedly treading on it inhibits water and air from reaching plant roots, whereas working from a path will keep the soil loose and well-drained.
While a depth of 15cm is adequate for some improved plant growth, raised beds can also be built with timber or brick sides to a ‘no need to bend’ height that’s ideal for your own comfort or at a convenient level for a wheelchair.
Waist-high beds are perfect for growing compact crops like beetroot, baby carrots, spring onions, garlic and a huge range of salad crops, as well as strawberry plants and herbs.
Incorporating wide coping stones or wooden benches around the edges will provide a place to sit, too, which is a useful design trick for getting the most out of ornamental borders that surround the patio.