How deep should a raised vegetable garden be?
The short answer is 5″ or more.
If you have or are planning to have a raised garden bed in your backyard where there is soil beneath it then you can build or buy a bed that is only about 5-6″ deep or deeper. Most of the plant’s root system is in the first 6″ of soil. Some plants like large tomato plants have a root system that can go down 36″ into the soil. But that’s OK even in a 5″ raised bed garden because the roots will grow into the underlying soil.
A good tip….till or turn the soil underneath the raised garden bed before you fill it with garden soil. It will allow roots to grow more easily and provide good drainage.
The purpose of the first 5″ of garden soil is to provide nutrients and moisture. This can be done with 50% compost, 25% coconut coir and 25% native soil. Then fertilize with worm castings. This mixture is the best garden soil available. If you want greener, brighter, healthier and more productive plants then try it.