new ornamental bed attempted

I have been looking to makeover my patio as a nice place to sit out during the summer -- hopefully while nibbling on treats harvested from our new fruit and veggie gardens.  This is what I had:

Besides being a mess, I didn't find the tall arborvitae or the overgrown, black-spotted fotinia inviting.  So we went for a full renovation.  In February I had out a tree service to remove all the offending plants.  That left us with the ability to see two yards over. 

So far, I had failed to make the area any more inviting (though the crabapple in the foreground sure is pretty when it blooms.) 

However, there is nothing I love more than a bare bed.  Starting from scratch lets me play with texture and color.  I got out to my local store on Friday (without kids) and picked out a bunch of bunch of low-maintenance plants.  First I selected a narrow clumping bamboo, borinda angustissima, to provide height and shelter.  It grows to about 15 feet in the Pacific NW and stays to about 2 feet around.  It has narrow leaves and a vase-shape that should provide a delicate screen as it matures.  I am in love with the darn things. 

Then I compared the bamboos to a bunch of possible ground covers (mostly grasses) to see if they would match.  In the end, I chose "June" hostas, "Ice Dance" carex, Japanese forest grass, and a "Tom Thumb" phormium to fill in the gaps at the foot of the bamboos.  The phormium is the only plant that might need some coddling past the initial first year or two of regular watering.  But look at this little detail it brings to the garden....  I had to have it!

On Saturday I set out to get my plants into the ground and ran into a disaster -- the worst rootbound-ness I have seen in purchased plants.  I even had to cut one of the pots to get the plant out of it.

I am so in love with this bamboo that I want to make it work -- but so far have failed to find good advice to help me.  I tried picking at the roots, I tried soaking them in water ...

Nothing worked.  Normally I would cut the roots with a box cutter -- but one of the bamboo's roots spiraled around horizonally so I risk shrinking the roots to mere inches and I am at a loss as to what to do.  So for now I am waiting for the bamboo specialist to return to the nursery.  I am hoping for definitive advice.  I really want these plants to flourish since they will shade me while I munch berries and tomatoes later this summer. 

What do you do in the face of excessive rootboundness?