What exactly is a raised bed? Pretty simple – it’s a way of creating a gardening area raised above the surrounding soil, varying in height from just a few inches to several feet. It is enclosed by a wood, stone, brick, or concrete block frame and enriched with compost, manure, or any beneficial organic matter.
Gardening using this method offers many benefits, such as an extended planting season, reduced weed growth, improved drainage, and enhanced soil quality. It also allows for less compacted soil which helps roots grow more efficiently. Other benefits include fewer instances of pests and diseases, the potential for higher yields, and the ability for the elderly and physically disabled to engage in gardening easily.
Raised beds are suitable for growing:
● Soft fruits – strawberries, blackberries, raspberries, and currants
● Vegetables – almost any kind of vegetable lends itself well to raised bed gardening
● Herbaceous perennials – excellent if you’d like to raise flowers suitable for cutting and bringing indoors
● Alpines – these kinds of plants love the improved drainage a raised bed offers
● Small trees and shrubs – depending on how big your bed is
● Plants that dislike lime – because you can fill the bed with almost any kind of soil, you can grow a wide variety of acid-loving plants, such as heathers and rhododendrons
Raised Bed Basics – Getting Started
Many garden maintenance experts choose to build their raised beds in the winter, but there is no hard and fast rule as to when the best time is. However, late summer will be best if your ground is prone to water logging in the winter. Bear the following tips in mind when building your raised beds:
● First, decide where you want to place your bed and how big it will be
● A width of less than one and a half metres is recommended because you don’t want to step or walk on them if it can be avoided.
● Pathways in between and around them should be wide enough to accommodate a wheelbarrow and provide disabled access. Plan on allowing 30 cm at least for a wheelbarrow and 45 cm for a wheelchair
● Think wisely about the materials. Options include timber, sleepers, masonry, or recycled plastic ‘faux’ timber. Timber is the cheapest but requires treating and won’t be as long-lasting. Masonry is expensive but will be permanent.
● Ready-made kits are available if you want to try the idea on a small scale first.
Constructing Your Raised Beds
First, clear the site of all existing vegetation, and level the surface. Mark out the beds using stakes and string and check the levels. If you plan to use anything other than masonry, the structure will need retaining stakes at the corners and along the sides at every one and a half metres. To provide a solid surround, the stakes should be sunk into the ground by approximately 35-45 cm. Using screws or nails, attach the retaining walls securely. Screws will be better, as they will reduce the likelihood of splitting. The soil can then be enriched with organic matter and cultivated.
If your beds are deeper than half a metre, remove the underlying topsoil and replace it with rubble, subsoil, or inverted turf. Once you’ve done this, you can return the topsoil you dug out. Enrich the topsoil with compost or manure and fertiliser, and firm in the layers to prevent settling. If the topsoil is unsuitable as a growing material, then leave it in situ and just loosen it up a little. The bed can then be filled with suitable soil.
Savings can be made by digging soil out of pathways and replacing it with gravel, bark, or other paving materials. Any turf you remove can be placed in the lower layers of the bed because it will enrich the soil as it decays. If you’re building your raised bed on top of a hard surface, you will need to allow at least 45 cm, but 60 cm would be better, to allow room for roots to grow. This will also reduce the need for watering.
Raised Vegetable Beds
Growing vegetables in raised beds has some significant advantages. They will be much easier to manage, the soil is free draining, and you can get your crops off to a good start earlier because the soil will be much warmer. You can also add a cover made of fleece or polythene to extend the growing season well into the winter. Root vegetables such as carrots and parsnips are brilliant for growing in raised beds because the soil is much deeper and free draining, and it lifts them above the level of common pests (the carrot fly, for example, only flies 30 cm above the ground).
Raised beds allow easy crop rotation, which is vital to successful veg production. Crop rotation prevents the build-up of pests and diseases that are soil-borne. With several raised beds, you can grow different crop groups in each one and change their position every year. It also allows you to make the best use of the soil and the nutrients it contains. A good example is beans and peas, which fix nitrogen into the soil, allowing the bed to be used for Brassicas the following year.
Because of the improved drainage, you will need to keep on top of your watering, as raised
beds suffer during drought.
Take care if you’re using wood for the retaining walls, as many of the timbers you buy will have been treated, some of which contain harmful heavy metals. If you’re unsure what’s been used to treat the wood, line the inside walls with polythene.
If you’ve decided to use new railway sleepers, be aware that these will have been treated with creosote, which can irritate the skin. This won’t be a problem if the sleepers are old, as the creosote will have dissipated.
Is a Raised Bed the Same as a Garden Planter?
Basically, the answer is no! Planters are containers that have been elevated and have bottoms to stop the soil from falling out. The bottoms are usually slatted and have some kind of semi-permeable membrane to allow drainage. Raised beds don’t have a bottom and are open to the ground, allowing roots to genetrate further to seek out available nutrients.
Raised garden beds provide a clean, beautiful and organized way to nurture a wide range of plants. Raised garden beds have become more prevalent in recent years as gardeners have discovered the many benefits of this unique type of garden bed. We hope this article helped explain how raised bed gardening works, the benefits of using them and how you can create a raised garden bed to start your own organic gardens at home.