Growing vegetables - raised beds and crop rotation

It didn't take us long to realise that raised vegetable garden beds were better for the type of gardening we do than anything else. We tried flat beds and no dig beds, raised beds that we could dig into and fluff up the soil gave us the best results. So for a long time, at least the last 12 years but probably closer to 20 years, we've grown our vegetables in raised beds.

A container of worm castings waiting to be added to the garden.

A raised bed can be anything from what we have - blocks built up about 15cm (6 inches), to large container beds with earth foundations 2 or 3 feet up from the ground, which are accessible by people in wheel chairs, the frail and elderly. Raised beds also enable you to rotate your crops, so if you have six beds, you'd only plant the same vegetable in that bed once every six year. Crop rotation is a system where you plant up each bed in a block of the same or similar vegetables, such as leeks, onions, garlic, shallots and chives together, or squash, cucumbers, corn, pumpkin and zucchinis together, then the following year, move them all to the next bed. The rotation usually goes something like this:

1. leeks, onions, garlic, shallots and chives - add lime and compost
   
2. legumes (the bean and pea family) - will use up the remaining lime from the previous year and add compost and nitrogen to the soil
   
3. leaf vegetables like lettuce, brassicas (the cabbage family), silver beet and spinach - add nitrogen such as blood and bone or aged manures and compost
   
4. root vegetables - carrots, parsnips, turnips, radishes etc - add compost
   
5. squash, cucumbers, corn, pumpkin and zucchinis - add a little aged manure, compost and potash
   
6. tomatoes, eggplants, capsicums (peppers) and chilli - add compost and potash

Potatoes can be part of the rotation but can be difficult to place because they are in the same family as tomatoes, so can't be planted for a couple of years before or after in the same bed. Often potatoes are planted in a their own separate bed, but again, they (or tomatoes) can't be planted in the same bed for another couple of years.

We started off with crop rotation, and while we think it's a great system, it doesn't' work for us. We try to keep our garden going all year and often finish a crop and plant a little fill in crop to keep the soil productive until the season changes. So while we often start off with neat rows, we usually end up with patches of different vegetables. We have found that if we continue to add abundant compost, this system usually works.

Our raised beds are edged with cement blocks. You could also use bricks or untreated timber. Make sure the timber is untreated because chemicals will leech out into the surrounding soil and vegetables. A raised bed will contain the soil well, even in a torrential downpour of rain and the soil will warm up, even in winter here, to allow us to plant all manner of vegetables and fruit.

The true value for me in a raised bed is that you can dig into the soil, worms can infiltrate your garden and the drainage is excellent. However, you can also build your raised bed on a cement slab if you wanted to and fill the frame with compost and soil. Raised beds are also good on top of clay. You can built the level up a bit with soil and over the years, the continual addition of compost and organic matter will break the clay down. Our garden is built on clay but over the years we've developed excellent fertile soil simply by adding compost and digging it into the soil that's there.

If you're starting out new this year with your garden, start with one or two beds, work out your gardening style and practise, then in following years, add more beds, until you have the garden space you need.

Leeks grown from seed in a tray and planted out.

Hanno planted out some new seedlings yesterday - leeks, zucchini and lettuce. Our garden is slow to start this year but is now taking shape. I can see another productive year coming up and I look forward to strolls in the garden in the late afternoon, picking snow peas and eating them in the garden surrounded by creeping vines and ripe fruit and listening to the birds.

Happy gardening everyone.

How to start a vegetable garden
Raised garden beds in the city - video
How to build a raised bed with timber edging - video