Do you HAVE to level out the ground under a raised planter bed?

I would level it out because otherwise the water will run off when it rains.

It's really up to you. If you are irrigating your plants with a drip system and mulching, I think their water needs will be met on a slight grade.

Plus you can level out the soil in the bed so that there is no slope at all!

: )

You can go either way, just depends if it will bother you or not when complete. If it is ever so slight, I would not worry about it.

The base of the raised planter needs to be level. This will allow watering/rain to cover the plants evenly. You can use brick, wood or dirt under the base.

Leveling is not required depending on the type of raised bed you are considering. It the raised section is only walls, then you are fine with an unlevel surface. If the raised planter has a bottom expected to sit on the ground, you will want it close to level so the raised bed is stable, but this again depends on the size/shape of the raised bed. If it's unstable, your risk it falling over.

It is in your best interest to even out the ground before making your raised garden bed