For gardens where the grower tills up a section of yard each year, the garden design is pretty straightforward — you make a big rectangle leaving room for the tiller or tractor to maneuver around the edges. Crop rotation is not really feasible on a small scale, since the dirt is being vigorously turned over each year and mixed up.
For permanent beds, a little planning is necessary. First, where? Look around your property and note what spots get morning sun, afternoon sun, all day sun. Are there places that get more or less sun during different parts of the year? For example on the northern side of my house, there’s a wide strip that gets no sun at all until about the spring equinox, and then gets ample sun there until about the fall equinox. On the other hand, I have a spot up near the woods that is full sun all winter and then mostly shade in the summer. As you make your observations, will will help to draw a map of your property and note any special characteristics through the seasons.
Unlike a tilled up garden, you are looking for permanent spots, and they don’t have to be rectangular or contiguous. You can make round, oval or triangular beds. You can take advantage of a small strip here and there. You do want to be sure that the spots you are picking are easily visible and that they are near the spots you normally go. You aren’t going to run out to snag a few lettuce leaves for your sandwich if the bed of lettuce is 250′ from the kitchen.
When locating the beds, try not to make your lawn chores more difficult. Placing garden areas next to a fence or other permanent structure will reduce the amount of edge you have to mow or edge around. If you don’t use a bag on your mower, you also want to verify you can mow without throwing weed seeds into your planted areas.
Finally, avoid planting in areas next to roads, driveways, drainage ditches and other places near pollution and toxic materials. (This may include areas right up next to your house.) Save those spots for ornamental, rainwater tanks or other non-edible uses. If at all possible, try and place your garden near your kitchen and outdoor living areas and make it roughly contiguous so there is one spot that gets routine attention, at least for the annuals.
Now that you have selected growing areas, you want to construct the bed edges. You can use large rocks, big tree branches, edging stones or whatever you have handy, or buy lumber. Modern pressure treated wood is safe but older pressure treated wood is not, so avoid reusing old pallets or stacks of old lumber unless you are sure they are not treated with arsenic. If you don’t want to use use even modern pressure treated wood, you can extend the life of untreated lumber by generously applying linseed oil to all sides.
There are two common mistakes to avoid: don’t make the beds so deep you have to walk or lean into them, and don’t fail to leave enough room between beds. If a bed is so deep you have to walk in it to reach the soil, you are compacting the soil and defeating the purpose of raised beds. For most people, 2′ is about the limit of their effective reach — young and tall people have a bit more, shorter and older people may have less. Design for the smallest person in the household who will be doing regular work in the garden. If this includes young children, you may want to designate specific smaller beds for them to care for that you can expand or replace as they get older. However, you can have have a 4′ wide bed that’s 20 feet long, provided you can get to both sides, so you can still have very large beds.
Space between beds is also important. I frequently see designs with 12″ of space between them. If you have a very small space to work with, this may be unavoidable, but 36″ of walkway is best. This leaves room for wheelbarrows, garden carts, spillover from large plants like squash (which will not respect the boundaries of its bed!), or even you on crutches if something happens. When you have room to work without fear of crushing your plants, time spent in the garden will be easier and less stressful.
In this diagram of my backyard, one whole fence line has been taken up by landscaping, herbs, fruits and the raised bed garden, making mowing easier and limiting the incursion of creeping weeds to as small an area as possible — bermuda grass from the lawn and creeping charlie from the field on the other side of the fence.
(By Nicole Castle)