How to Install Drainage in a Raised Bed

dallasdrainagepros.com
Installing drainage in a raised bed may involve several components. First you will want a point of drainage at the base of the wall or even below ground level, assuming you have somewhere to drain the line to. Connected to this line could be surface drains and/or a French drain.
The purpose of surface drains is to collect rain that may overwhelm and flood a boxed in flowerbed or vegetable garden. With fixed walls comes the potential for water to become trapped, and by installing small drains along the surface, you allow excess water to be collected.
The purpose of adding a French drain to a raised bed is to (a) relieve pressure from a wall that can be created from excessive moisture as well as to (b) allow subsurface water a way out, which allows it to cycle, keeping the moisture fresh. Standing water and moisture can become stagnant and moldy, which will damage plants if left untreated.
In this project we decided to use both methods to create a superior raised bed drainage system. We show you step by step just how we did it, and how you can do it too. Hope you enjoy!

[@joeshmoe7789]

I always found drilling a few weep holes in the wall with stones around it worked well.

[@DallasDrainagePros]

Yes - depending on the situation that can be a quick fix!