How deep should it be?

I don't think there's a 'one answer to fit all' for this question. It depends on what you'll be planting and how deep the root systems are. For example, lettuce doesn't as much as say, carrots. In general, you might say a minimum of 6" but 12" is better. But here's a good guide to look at when building a raised bed!

https://learn.eartheasy.com/guides/raised-beds-soil-depth-requirements/

I agree that 12 inches is ideal, but you could definitely have just 8 and be fine. I hope you have a successful recovery!

I saw a wonderful one that was as high as standing at a table and they made it U shaped but squared off so it was huge! I'd say the dirt debth was 6 or 7 inches deep. They had lots growing too!

Hi L.L. - Best wishes on your recovery and love the garden therapy! You want a little space at the top - 10-12 inches. Remember, the dirt will settle and especially with rain too. Hugs, Holly

I had one built for me this last spring for the same reason. 10” to12” is the best depth. Mine was 8” way too shallow and I was watering three times a day. We had lots of days in the ninety’s. I went to a big box store and purchased a watering system with adjustable sprinkler heads which I could snap the hose onto several times a day. The beds also required more fertilizing as the nutrients washed with the continuous watering. I planted green beans, onions, tomatoes (heavy feeders) peppers and a variety of herbs. Under the raised beds I planted beets and carrots around circumference of old beds. Havent harvested those yet as I am getting over my back surgery. They have lots of nice greens so hopefully there will be good veggies too! All I know is if I had died it would have taken at least 20 undertakers to wipe the grin off my face. nothing better for the soul than dirt under your nails and a bountiful garden.

waist high for most adults is in the 36" range ... so the dirt should be as deep as you build the raised bed --- leave about 10" from the top of the soil to the top of the bed --- and you might want to consider installing a 2" x 12" cap all around the bed so you have a place to sit, place your tools, bag to collect the produce or cut flowers, etc.