Our first thought had been to just replace the redbud, but a local gardener we respect had suggested putting something interesting in the center to provide the shade the hydrangeas and hosta need - something like nandina or a fast-growing annual like a castor oil plant - and put a shade tree outside the garden to the West - like an oak or pecan.

The garden gets sun at two different times (b/c of a large silver maple to 10 yards to the S), from about 10am to noon, and from 3 or 4pm to sundown.

Attached is a picture for reference - the lamium has died out since this was taken, and the coneflowers are behind the bench.

Any thoughts?

for maritime NW gardens, but some are hardier (includes photo & description)
http://www.greatplantpicks.org/plantlists/search/

plant profiles & more (many hardy to 0 degrees)
http://www.npr.org/programs/talkingplants/profiles/index.html

Nandina is beautiful & castor dramatic (maybe not too late this year).

Most of my gardens receive shade from tall fir trees, so have dappled sunlight throughout the day. I plant nearly any perennial that is listed for part sun & just see if it works. Some don't bloom & just flop, but others work fine. I've enriched the soil with composted manures and keep it mulched so moist not dry.

Masterwort, Astrantia - long lasting late spr - fall frost bloom (plus flowers dry well for winter)
Japanese anemone - spreads freely, but so showy midsummer until frost. Would lean against the hydrangea & stay more upright.
Lady's mantle, Alchemilla mollis - foamy yellow long lasting blooms that fill space between plants
Sweet William - biennial habit, long blooming
Crocosmia Lucifer - a hummingbird favorite
Meadowsweet Filipendula rubra Venusta - tall towering cotton candy like blooms for about 3 weeks in summer) spreads a foot a year if it likes the spot - give it dry shade & it might not spread so much. Also slow to establish, so expect blooms the 2nd summer after planting. The white version is also nice & pops in the shade.
Bleeding heart Gold Heart - if kept moist will have nice foliage all summer long here. The last of the blooms fell off last week. Another hummer favorite.
Heuchera - 2 that I've had success with are Palace Purple & Caramel. The others were either overrun by a groundcover, didn't establish by winter, or root weevils ate them.

July 2011 of garden planted in March where we used to have the raised duck & rabbit coops you see in the background. Rich soil.

Hope that helps,
Corrine