Excellent success with liriope types and painters pallette....

Maples are shallow rooted. I have four 40 yr old Japanese maples that NOTHING grows under....mondo grass and liriopes don't stand a chance. Baby tears surviving under a 9' Crimson Queen Jap. maple. Pots work well. Do some research for your area...which is where???? We have a lot of potheads here, happily growing hostas...but not many who are growing them under maples for very long. Where are you? It will make a difference on how you handle your hostas in pots.

-Babka

{{attachment:1455720}}Elegans under a very big maple (Schwedler / Norway) planted many years ago. I planted a division of this plant high under a Crimson King and it didn't last.
I think Babka's observation of the problem suggests a solution. Spinout bags are treated with lead to keep roots out, but they also keep roots in. If you used the spinout material, but instead of a complete bag made it long and deep with an open bottom this might allow a hardy, giant hosta to establish a root system below the maple root system.
This might explain why this Elegans has flourished for many years (17\-20) right under this maple. I think the supporting root system must be under the maple's root system. This Elegans must have been tough enough to grow down below the maple's root system. I don't see how it could look so god year after year if it was competing constantly with the Maple's aggressive root system.
When I planted a division of this plant on a mound next to a Crimson King it probably never had a chance to get through a very well established root system. The roots on the maple are on the surface and sprawl all over.
Liza, I think the raised bed is a big problem. They grow fine at first and then the maple roots move in and the hosta don't have much of a chance to get past the level that maple roots favor. They probably migrate up to the new ground level you have established in the raised bed. Aggressive roots will grow right through regular landscape cloth.
I think 16 inches or so root depth is typical. Spinout bags come in 15 1/2 tall sizes. Using two opened up can get you deeper than the 'maple root zone'. I think treated ground cloth is available which might be the answer for raised beds as long as you place a barrier a couple of feet deeper than the ground level around the outside perimeter of the bed or use a layer at the bottom of the raised bed. I don't know the cost, but it should be less expensive than a lot of fabricated bags.
Sounds like a lot of work to me, but it depends on how important it is for you to get this to work. Based on the work you have done so far it seems you are not ready to quit.

Good luck, whatever you try, Jon

Thanks all for the feedback! I think I might try and find the fabric to line the bed with. I've messed with the beds this long that maybe, just maybe, I will have sucess this time. Im doing a gut job out front and hopefully I will be able to post my pics so you can see what Im dealing with. I dont think I will be replanting all of the hosta out front though and maybe just switch some of the smaller ones for the larger ones that are more established in other areas of my yard. Now onto the potting of said hosta. I live in zone 5 Illinois. And I know for fact that I will not have enough room for all of these as most of my backyard is all sun or over filled with hosta or other plants so I have to come up with something. I will check out the plants that were suggested and maybe I can place these around the Japanese Tree area. Oh and 1 more question. I have numerouse hosta that were self seeded. I call them my no names. They are HUGE and hardy as all heck. Why is this? Thanks again.....Lizbit.

Sorry for the pics posting twice. Not sure how i did that.