There are a few factors that must be considered when choosing where you are going to put your raised vegetable garden bed. Most of us will be limited to a small number of vegetable garden beds in a suburban backyard, some of us will be luckier and have more available space to cultivate. The size and number of your raised garden beds will determine exactly how productive they will be and how much food you can reasonably expect them to produce.
For complete self sufficiency a family of four would be well provided for with a vegetable garden of about 50 square meters. A family of six can be provided for out of the same area by planting more main staple crops. Now 50 square meters is a very substantial vegetable garden, a traditional garden bed 10m X 5m as an example or five raised garden beds that are 5m x 2m.
If complete self sufficiency is your goal then your garden will need to be of these proportions to ensure an adequate year round supply of food and an area of this size will take up a significant percentage of the average suburban block. Fortunately raised garden beds tend to be far more productive than traditional gardens and with good gardening practices and a little experience you may find 40 square meters more than adequate. When selecting the location of your raised vegetable garden bed you must first examine your available options and keep a realistic expectation of how much food a given area will produce.
Although in the past my family has been virtually self sufficient as far as producing vegetables at home a change in the shade patterns reduced the available area for vegetable gardening and I was forced to reduce the size of our garden beds, allowing it part of it to return to lawn. As a result we no longer grow our own potatoes, which compensated for the reduced garden area. Potatoes are a readily available staple part of the Australian diet and can be purchased quite cheaply when compared to other vegetables our garden produces. If your garden bed is limited in size it can still present substantial savings in your budget by carefully selecting what you grow and what you buy, so don’t feel discouraged if your vegetable patch is not fifty square meters.
I mention shade because it is a very significant factor in how productive your raised garden bed or any other garden will be. With very few exceptions most food crops require a warm sunny position with at least six hours of direct sunlight every day. When selecting the position of your vegetable garden it is important that you consider how much sunlight your prospective location will receive. In the previous paragraph I mentioned that changing shade patterns made part of our garden not viable.
This happened when our neighbors to the rear of our suburban 1/4 acre block decided to knock down their house and build a duplex, with one of the flats being built exactly at the minimum legal distance from our rear fence which is adjacent and to the north of our vegetable patch. This meant that a section of previously good garden was in permanent shade for about five months of the year and received limited direct sunlight for the majority of the rest of the time. The impact of this was immediately noticeable and serves to illustrate how important it is to familiarize yourself with the shade patterns of your prospective garden bed throughout the year.
Bear in mind that as the seasons change the sun moves in the sky, here in the southern hemisphere just above Sydney the sun is virtually overhead in summer and fairly low in the northern sky in winter. Those in the northern hemisphere will of course see the sun go south in winter. Failure to take this into account may result in a garden bed that can only be cultivated during certain times of the year.
Try and site your garden beds at right angles to the axis of the sun and run your crop rows to the north and south (regardless of what hemisphere your in) and you will find that shading from your crops themselves will be minimized and the soil will be warmer, particularly during the colder months.
Problem With Your Drainage?
Drainage is less of an issue with raised garden beds but still requires some consideration. Making the beds higher is an easy solution but you will find that if your native soil is heavy clay or of a similar poorly draining composition that you might experience surface water runoff during periods of heavy rain. In extreme cases you may need to build your raised garden on top of a bed of gravel and use agricultural pipes to transport the excess water away from the site. Consult your council or local government to ensure that the water is dealt with according to local regulations.
Perhaps one of the situations where raised garden beds may be the only option is on severely sloping ground. A traditional garden bed may be eroded or completely washed away in heavy rain on a steep slope. The Incans and many other cultures used raised garden beds in a series of terraces to combat soil erosion with good effect. We can see in the picture above on this page where the raised garden beds have been incorporated into the overall landscape design with huge success, permitting steep ground to be reclaimed and put to good practical use while enhancing the appearance of the gardens surrounds.