Have you ever wondered exactly how tall a raised bed should be? Here's the answer: 11 and 5/16ths. Yep that's right, 11 and 5/16ths. Of course not! The real answer is that the height of a raised bed is dependent on a number of factors which makes each situation different. Today's Friday Fives post is another raised bed design post all about the height considerations when building a raised bed. Hopefully this will be helpful as you plan you fall garden or even your spring garden for next year!5 Considerations for Determining How Tall A Raised Bed Should Be!
- The most important thing for your plants is the soil. It has all the nutrients and its where all the water will be stored after rains. If you have rich, compost like soil already than you don't have to worry about how tall your bed will be. In fact then you might not even want to worry with raised beds unless you just want them for convenience (more on that later) or appearance. If your soil is less than perfect - i.e. rock or clay - you will want more height so that you can add better soil on top where the plants will be happy. Raised beds will eventually improve the soil conditions underneath as organic matter trickles down into the clay areas.
- What materials do you have available to use for you raised beds? If you are planning on using lumber of some kind then you can build as high as you like fairly inexpensively. When it comes to stone you will need some kind of mortar to hold the stones together as you gain height. The same is true with concrete retaining wall blocks. The other difficulty with tall stones or concrete raised beds is the time involved in building them. The taller they are the longer it takes! However you could build a layer or two one year then add to them the next and gradually build height.
- Consider what plants you are growing. Plants like potatoes that like to be buried then covered as they grow may need deeper raised beds than a more shallow rooted plant. Vegetables with long roots like carrots or parsnips should be considered for the height of the raised bed especially if the soil quality underneath the raised beds is very poor. Carrots like loamy soil with very few obstructions like rock or clay. They find it difficult to grow long and straight and tend to end up producing funny looking tap roots!
- The taller the raised beds are the quicker the soil will dry out. As you build height you also build surface area around the sides. The sun and air will move against the outside of your beds which increases the rate of evaporation and will dry the beds out faster. Raised beds in general dry out faster than gardens planted in the ground so this may not be a major factor but should still be considered.
- Convenience! Raising the height of a garden as much as 24 inches can be a great boon for the handicapped or those who have trouble bending in the garden. It makes weeding, watering and harvesting much easier on the body. Tall raised beds are a great option for those who are having trouble gardening but still want to participate in the hobby they love!
I think in general that raised beds of any height improve a gardener's ability to garden. They keep the soil in place and usually involve a higher quality organic rich soil than what was originally present in the soil. If money is a concern consider building raised beds in mounds that slope down to the edges without any type of formal sides. It's still a raised bed and will do the job nicely!
For more raised bed design tips please read Designing a Raised Bed Vegetable Garden: 11 Things to Think About!