Fruit and vegetables can be grown in small spaces using raised beds

One of the biggest obstacles faced by kitchen gardeners is a lack of space to grow their favourite crops. A traditional allotment for example is 250 square metres - the size of a doubles tennis court – but with the clever use of raised beds, you can grow a surprising array of fruit and vegetables in a relatively small space.

Using raised beds in a garden can have many advantages, including:

* Improved drainage for heavy soil

* The soil warms up faster in spring for earlier direct sowing

* The area can be filled with appropriate soil for what you intend to grow

* Ease of access for people with mobility problems

* Conveniently placed, next to your kitchen for instance

* Compact spacing for a wider variety of crops

* Weed suppressing due to compact spacing

* Can be whatever size you want it to be.

One disadvantage of raised beds is that they tend to dry out quicker, and therefore will need more watering during the growing season. Spacing for crops is often closer in raised beds, ultimately meaning they are harvested smaller. This allows for a faster turnaround and succession of other crops to take their place. People often ask me about growing vegetables in small spaces and how to crop rotate.

Although crop rotation is a very good practice that manages the build -up of pests and disease and the depletion of specific nutrients in the soil, if you’re growing the same crop year-upon-year, it is not practical and near impossible to achieve in small gardens with only one or two raised beds. However, crop rotation doesn’t hold the same importance in raised beds as it does in open beds. This is because raised beds are often topped up and should have plenty of new material added each year, limiting the likelihood of diseases taking hold such as club-root on brassicas. If you do have the space, practising crop rotation in raised beds is still always advisable.

If you plan to build your own raised bed here are some important points to consider:

* Define how large your raised bed needs to be, and where you would like it

* Pathways should be wide enough for a wheelbarrow which is 45cm (18in)

* Materials: timber is the cheapest material but even when treated it is the least long-lasting; sleepers are long-lasting but costly and bulky; masonry (for example, brick, stone or paving slabs) is costly but permanent. Recycled plastic ‘timber’ lookalikes are another option but can also be costly.

* Walking or stepping on raised beds is best avoided, therefore ensure widths of less than 1.5m to allow access from the sides

* Ready-made kits are available for small projects

* Run vegetable beds north to south for even light levels.

Consider the height of a raised bed carefully, as it will be surprising how much soil is needed to fill it. A raised bed 1.3m in width x 2.6m length being 15cm high will need a bulk bag quantity, roughly 800kg of soil to fill it. If you are lifting turf to build a raised bed place the upturned turf in the base of your new bed. This will release valuable nutrients as it breaks down.

Here at RHS Garden Harlow Carr we have many raised beds, so pop along for a visit and please feel free to ask for advice and guidance from any member of the kitchen garden team.

Jobs for the Week

* Continue to direct sow seed such as carrots, radishes, cabbages and parsnips.

* Support peas with twiggy material

* Start watering emerging plants regularly

* Harvest asparagus

* Mulch fruit trees

* Protect fruit blossom from late frosts

* Check for pests and diseases on crops for early detection

* Finish preparing beds that are intended for tender crops to go out in June.

With thanks to Francesco Ponziani, Horticulturist at RHS Garden Harlow Carr

DIARY DATES

From 24 April: Tulip Trail Tiptoe through the tulips at RHS Garden Harlow Carr as the garden celebrates the colour and scent offered by these beautiful bulbs. Get inspiration for your own garden with a range of striking planting schemes featuring more than 100 varieties of tulip – from traditional beds and borders to quirky containers. Pick up a trail leaflet to guide you to the highlights, and to see Curator Paul Cook’s top 10 tulip recommendations. Don’t forget to visit the Plant Centre to pre-order your bulbs for striking displays next spring. Normal garden admission applies.

29 - 30 April: Spring Plant Festival including the Tulip & Daffodil Show Don’t miss the chance to buy a range of beautiful plants from specialist nurseries. This hugely popular event, which includes the RHS Late Daffodil and Tulip Competition, will provide great inspiration for your garden at home as well as a wealth of advice. The weekend also sees the launch of the Harlow Carr Spring Woodland Collection in the Plant Centre. Normal garden admission applies.