How to Create a Raised Bed Garden
When you decide to start a raised bed garden, choosing the right size is the first step. The ideal size should be no wider than 4ft. so that you can reach the plants easier, but the length is strictly up to your own needs. The 4X4 plan is the most popular, but it is a personal preference what size you make it.
Use standard lumber for your construction of the frame. For shallow root vegetables such as radishes, lettuce, and spinach a simple frame made from 2X6 lumber will do. 2X12 boards will be needed if you choose to grow larger vegetables such as corn or tomatoes so that the soil can be built up to at least 10in. deep.
Whether or not to use treated lumber when you build your garden frame has been a source of controversy. Untreated lumber will rot in a short span of time, and you will have to rebuild your garden in a couple of years. However, using treated lumber for your raised bed garden frame is not a good idea since it could bleed chemicals into the soil. These could be absorbed by the plants and ingested by you.
The safest way to go would be to use untreated wood. Treated wood is much more convenient though so the choice is up to you. Research has found that whatever chemicals would leak into the soil would be a very small amount and harmless.
To make things easier, you should buy your lumber precut. The ends should be even to prevent soil from leaking out once the frame is put together. This would be very hard to do unless you own a large saw. A circular saw or handsaw would be the correct tools to do this job.
3 four inch ribbed deck nails will be needed for each corner of your frame. Other types of nails are not strong enough to make sure that your frame will stay together for any period of time. The weight of the soil and the plants together will push the boards apart if smaller or weaker nails are used.
The frame should be built on a level and dry surface. The frame will turn out much sturdier if you put it together on a deck or driveway. You might need some help moving the frame once it is finished as it will be quite heavy. Leave a minimum of two feet, preferably three, in between the boxes so that you can maneuver around them. Be sure that you have chosen a good spot because once these are set and filled with soil, it is impossible to move them.
You will only need six to twelve inches of the best possible soil for your raised bed garden. If needed, the plant roots will push through to the soil beneath. Make sure that the soil you fill the bottom with contains as much nutrients as possible. This will prevent your plants from having to shoot their roots into the ground beneath.