Looking to add worms for a 4x8 raised bed garden.

Using them for fishing or for mulching/ decomposing?

Throw in a can of night crawlers
Throw in a can of red wigglers
Let them fight it out

Start a compost pile. Perpetual worm factory right there. You don't have to do anything, one day they all just show up

You should be adding good organic material to your beds on an annual basis. If you do that the worms will show up but it will take time. If the enviroment is not right you can add all the worms you want but they will not stay for any length of time.

I started a raised bed 3 years ago on what was previously turf. Every year I worked in chopped oak leaves and horse manure. My worm population went from almost non-existent the first year to 2-3 large worms in every shovel full I turned.

Naa, Mandeville/Covington area