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Ask the Master Gardener: Customize growing with raised beds

By: Trish Grenfell, Placer County Master Gardener
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Question:  I have decided to grow some vegetables in a sunny spot in my back yard.  I plan to just turn over the earth and add compost — as per the instructions at my garden center.  But many people grow their gardens in large, flat garden planters.   What is the advantage gained by that extra effort and expense?
Answer:  Raised beds make it easy to create a deep, fertile soil that’s high in organic matter. They allow you to create a custom growing medium that may or may not incorporate your native soil, depending on your native soil.   (Note:  Mix the top several inches of native soil with several inches of whatever you put in the raised bed to prevent abrupt soil boundaries that could impede drainage.)   If you have more than one raised bed, you can choose a different type of soil mix for each, tailored to the plant types that will grow in them.
A soil appropriately amended should dramatically increase the yield of the garden.  In addition, the beds tend to warm up earlier in the spring and dry out faster, extending the growing season.
In addition, they save on the amount of fertilizer and compost used because it’s concentrated just on the planting beds.  And you won’t be stepping on the planting bed in the off season, compacting the soil and making it hard for roots to grow.
These beds are usually 4 feet wide and can be as long as desired. The height can be almost any dimension, although 12 inches seems to be universal and allows for good root development.  Or think of these beds as a landscape feature, placing them attractively within your backyard plan.  
And you don’t have to use wood as the bed walls.  If you are using a rock motif in your plan, use rocks or rock veneer to form the beds.   Or bricks are another alternative.  And hard angles are not the only solution; you may use round beds with vegetables, herbs, and flowers in various designs.  
If you or anyone else tending the garden has a problem with kneeling or bending, a gardening bed could be raised to the height appropriate for that gardener.  In fact, even if you have no disabilities, it is usually more convenient to weed a garden while standing or sitting in a chair.
Good luck on your garden, raised or not, and call the Master Gardener Hotline at (530 889-7388 with your questions.