What do you think about this plan:
Ditch the hostas (I'll put them in the back yard.)
Move the candytuft back a bit, and plant green ice mini roses in front of them, going down the entire row of boxwoods....they would then continue onto blend in with the rest of the green ice roses that are around the tree. BTW the roses closest to the tree were purchased last year. I liked them so much I bought more and just planted them in front of them (that is why they look so puny.)

Beautiful home with classic landscaping bones. Fine architecture is such a pleasure to landscape off of.
I would suggest interjecting some silver foliage between the green of the boxwood and the green of the lawn to give it some pop.
Perhaps some artemesia silver mound ( a perennial ) interspersed with some white flowering annuals such as white petunias , dwarf nicotiana, white snaps or some white nemesia.
Simple , clean lined and classic that will add a sense of division via color and texture between the green hedge to the green lawn.

If you were in a milder climate I would have recommended Anthemis cretica which has both silver foliage and white flowers but I'm at a loss of perennial plant choices that are appropriate for your zone 6 climate.

Japanese painted fern
silver leafed pulmonaria
variegated carex

just to get you started

Green Ice is almost more of a polyantha than a mini, and will get to a respectable size over time.

Nice the plants combinations.I continue with red loropetalum,spirea,summersweet...
{{gwi:32280}}

Started googling some of the suggestions.... I like the pulmonaria. Confused as the summersweet gets 5-8 ft tall? The boxwoods are 2 ft tall tops

You densily plant and some prune the summersweets to control it' tall under the boxwoods.

Campanula white clips for white flowers...

Some varieties of creeping phlox bloom forever.

Brunnera Jack Frost where there's shade.

Annual--dusty miller

Artemisia is more of a shrub--gets 2' tall, even in the desert...

Germander. Also, lamb's ear.

I like the campanula suggestion, especially C. poscharskana 'alba' and brunnera jack frost together. ( been there and planted that combo, it's fantastic )

artemesia is a modestly large family. artemesia schmidtiana silver mound will rarely reach over 12 inches - its usual height is around 8 to 10 inches. on the otherhand, the more commonly seen artemesia powis castle can easily reach 3 feet or taller and will become woody in its third year of growth, unlike silver mound that rarely if ever will become woody due to its dependable total winter dormancy even in mild zone 9-10 climates.

For a truly uncommon artemesia try artemisia lactiflora 'Guizhou'. It has the most unusual foliage color - sort of a purple hued blackish silver and will grow to about 5 feet tall.

Whoops! I was thinking of powis castle--sorry! (It died to the ground and grew to 2.5 ft every year where I had it.)

Love the suggestions....thank you! I almost planted white clips 3 years ago....can't remember why I decided against them but they are so lovely....revisiting the idea with the combos you both suggested. Thank you!!

It's a bit too late into the season but next year you could plant wax begonias, they come in white or red and would look great contrasting the boxwood.

And for the winter you could plant pansies or violas which might do well depending on how cold it gets.