Your bed is lovely. What's the issue? If it's watering, you'll have an equally busy task if you put them in containers. Any chance of skimming off three or four inches of soil, and putting down some sort of fabric block and then build it back up again over it? They do all look like annuals, so if you're completely replanting, it's my best suggestion.

i am not one to prefer landscape fabric for any use .... long term.. it doesnt work ....

what are the trees ... there are some.. where it is simpler to just give up ... lol ... this is a huge issue.. for those of us who grow hosta ...

there are plants that can compete with competitive trees ... but it is usually not the water hog annuals that you show in the pix ... so plant selection might help you ... and i wouldnt be surprised if natives might not be the way to go ... forest plants have mor etolerance to deal with forest trees .....

the problem with bad trees.. is that every time you dig a hole.. you sever fine feeder roots ... those that steal water ... and each one cut.. return with two replacements.. to steal more water ... and the more you water.. that faster and more aggressive the tree roots become ...

many hosta peeps do grow in pots... but burying them really gets you nowhere.. in the long run ... because you need drainage holes in the bottom of the pot ... and if you water the pots.. the tree WILL find the drain holes... and invade ... so you stay on top of the soil ... and move the pots a couple times a season.. to insure the roots are not invading ...

i once had a retaining wall like yours.. i ended up giving up the spot.. and moving the blocks somewhere else .... sometimes you just cant do what you want.. in a certain space ...

and just to be clear.. the drip irrigation.. is watering the trees.. as much as your favored plants ...

ken

Sometimes you just can't do what you want.... That pretty well sums it up, I suppose.... : )

You can't fight Mother Nature. Well, you can, but you probably won't win.