Gardens

5 raised bed gardening mistakes – and Gardener Scott's advice on how to avoid them

These raised bed gardening mistakes could compromize your vegetable harvest; Gardener Scott gives his top tips on avoiding them

raised bed gardening mistakes
(Image credit: Leigh Clapp)

These raised bed gardening mistakes could be the reason why your vegetable plot isn't doing so well. If your kitchen garden ideas involve building raised garden beds, there are a few things you need to get right to give your veggies the best possible start. 

As gardening expert Gardener Scott points out in a recent video, people often assume that a raised garden bed has 'magical properties' that means you don't need to maintain it. This couldn't be further from the truth, he says: 'You still need to garden in your raised bed just as you would anywhere else in the landscape.' 

These are the most common mistakes to avoid while tending to your raised garden beds.  

See: Raised bed garden ideas – build raised planters now for productive, low- maintenance gardening

1. Using a wrong-sized bed

raised bed gardening mistakes

(Image credit: Kasia Fiszer)

Whether you're learning how to grow potatoes or another crop, the size of the bed will make a big difference to your yield – and the ease of gardening in a raised bed. 

'Make it wide enough so that you can reach the entire bed,' explains Gardener Scott – if you want to make the most of a freestanding bed, make it around four feet wide, so that you can walk around it and use both sides. 

On the other hand, if your bed is against a garden wall, 'don't do four feet wide' – you won't be able to reach all the way to the back, wasting half the bed. 

Height also matters, especially if you have mobility issues (or even just a bad back): 'If you have mobility issues or don't like working on your knees, you're free to adjust the height to whatever works best for you,' says Scott. 

2. Choosing the wrong location for your bed

raised bed gardening mistakes

(Image credit: Leigh Clapp)

This one seems simple, but Gardener Scott says that many gardeners make this mistake. Garden beds are 'not magical', he reiterates: they can't 'overcome the wrong spot. If you've put your raised bed under a tree in full shade, and your plants aren't doing so well, it's probably not because they're in a raised bed, but because they're in the wrong location.' 

All vegetables need as much as sun as they can get to thrive, so always choose a sheltered position in full sun for your raised garden beds. 

And don't forget to position them in a way that's accessible for your irrigation system or garden hose. 

3. Not leaving enough space between garden beds

raised bed gardening mistakes

(Image credit: Harrod Horticultural)

It may be tempting to have your garden beds neat and close to each other, but this will make moving between them difficult. Scott advises to leave 'ample room to move your wheelbarrow in', or room to bring in compost and mulch. 

That doesn't mean you need six feet between beds – just a wide enough path to the side of your beds, and two feet between them so that you can walk between them easily. Even watering will become 'difficult' if you 'place them too close together', warns Gardener Scott. 

You can still have raised garden beds as part of small garden ideas 

4. Choosing the wrong soil type

raised bed gardening mistakes

(Image credit: Leigh Clapp)

This goes back to Gardener Scott's main point about raised garden beds – they're not magical, so 'taking poor soil' from just anywhere in the garden and filling the raised beds with it will give your poor results. 

'As a bare minimum, you need to add some kind of organic material to your soil, like compost', says Scott, 'and if you can, get a blend that already has compost and nutrients in.' 

You'll then need to keep adding organic material 'on a regular basis' to keep the soil nutritious. 

5. Choosing the wrong material for your bed

raised bed gardening mistakes

(Image credit: Leigh Clapp)

Scott admits that he likes wood best but does realize that 'wood will decompose and rot over time, so my raised beds will need to be replaced'. Especially if you live in a damp and humid climate, 'you may want to bypass the wooden beds completely', and maybe consider galvanized steel instead. 

Brick and stone are also great solutions – 'materials I don't have to worry about decomposing'. Build your raised beds to last and enjoy a crop of homegrown vegetables year-after-year.

How deep should raised vegetable beds be?

Raised vegetable beds should be at least 8 to 12 inches deep, however, they can be deeper if you have mobility problems or if soil drainage is poor. In the latter case, you can back-fill the raised bed with a porous growing material. 

What do I put on the bottom of a raised garden bed?

You can fill the bottom of a raised garden bed with a number of organic materials, including straw, grass clippings, wood chips and leaves. Place cardboard – or any suitable weed barrier material – over this organic layer, weighing it down with a few bricks or pegs. This will allow the organic material to turn into rich compost, into which you can mix soil for a rich growing environment. Usually, you would aim for a mix of 30% compost, 60% top soil and 10% potting soil – the latter will help drainage.