Raised beds are also known as deep beds, and though organic gardeners didn’t invent them they know the true value of them. For large or small gardens, for vegetables, flowers or a mixture of both, ‘raised’ deep beds are ideal. You’ll be surprised what you can grow.
They are usually double dug when they are first made, so as to give a good depth of workable soil.Advantages of raised beds for vegetables
• Space is used efficiently as there is more growing space in small plots
• No soil compaction as you don’t walk on the bed
• Good soil structure easy to maintain
• Less digging once beds have been made & forking before planting often all that is needed
• Good drainage through deep soil
• All-weather access – walk on paths not sticky soil
• Easy access to crops from both sides
Disadvantages of raised beds
Deep beds drain well and are excellent for overcoming waterlogged Northern Irish soils so keep newly sown seeds and seedlings well watered as the excellent drainage can dry the soil too quickly before seedlings have germinated and established.
• A few crops not particularly suitable – eg potatoes which need ridging to stop tubers going green
• A lot of physical effort is needed to make them (but it’s worth it)
• Tall plant supports more difficult – eg runner beans as no firm soil to put stakes in.
Suitable edging materials
• Old wooden boards – old floor boards, but they rot eventually
• Concrete building blocks on edge – durable, relatively cheap, but very heavy to install
• Old roof tiles or slates
• Old bricks on end
• Logs – will rot eventually
Suitable path materials
• Space beds about two feet apart to allow access paths.
• Grass – needs regular cutting – making sure your lawn mower can get between the beds
• Straw over thick newspaper – needs regular renewal
• Bark, sawdust or shavings – needs regular renewal
• Gravel – needs edging to beds – expensive
• Slabs, bricks – expensive
• Landscaping fabric – unattractive – best with bark covering
How big should a bed be?
• Any length or shape, but no more than four feet wide at any point.
• Up to four feet wide allows you to reach in from either side
• Of a length that isn’t tedious to walk round
• Long beds are better split, with a path between them.
• Try a four by four bed as a starter
When is the best time to make a raised bed?
During autumn, so that the soil can be weathered by frost to give a good tilth or in early spring once the soil is dry enough to walk on and dig.
Making a raised bed by double-digging
Double digging is best for medium to heavy soils, where there are a lot of weeds or large stones, and particularly when the bed is being made in a lawn or other grassland.
1. Mark out the position of the bed accurately
2. Remove any turf or vegetation, put to one side and then bury it in the bottom of the bed as you proceed to dig it (not perennial weeds though)
3. Working across the bed, dig out soil to a single spade’s depth (removing any stones and perennial weeds as you go) and place it to one side
4. Loosen the next spade depth down with a fork, removing any stones and perennial weeds as you go.
5. Fork well-rotted manure or compost into this loosened soil double digging
6. Dig the next top spit of soil (removing any stones and perennial weeds as you go) and place onto the loosened and manured soil
7. Fork manure or compost into this replaced top spit of soil
8. Repeat steps 4-7, working down the length of the bed
9. When you get to the end of the bed replace the soil which was set aside and add manure or compost
That’s the last digging you’ll do. It will only need forking in future years. Even our old friend scutch (couch grass) will now be relatively easy to remove.
Making a raised bed by single-digging
Single digging will probably suffice on light, free draining soils as long as there isn’t a layer of compacted stones in the top soil.
1. Mark out the position of the bed accurately
2. Remove any turf or vegetation, put to one side and then bury it in the bottom of the bed as you proceed to dig it (not perennial weeds though)
3. Working across the bed, dig out soil to a single spade’s depth (removing any stones and perennial weeds as you go) and place it to one side
4. Fork well-rotted manure or compost into the trench single digging
5. Dig the next spit of soil (removing any stones and perennial weeds as you go) and place onto the manure/compost layer
6. Fork manure or compost into this replaced top spit of soil
7. Repeat steps 4-6, working down the length of the bed.
8. When you get to the end of the bed replace the soil which was set aside and add manure or compost
How should I plant my crops in a raised bed?
• Space plants relatively close together in blocks rather than rows to make best use of the space available
• Closely spaced rows either across or along the bed are a possibility with crops like carrots, parsnips, radishes
• Crops which are transplanted should be spaced in either a square or offset layout
(Article source: 50 Connect)
