Neither will be of any interest in summer (except for the one yellow-leaved cultivar) unless you train a summer-blooming clematis up through the shrub, after it is up to size. Burkwood viburnum has better-looking foliage, you might want to try that.

Yeah both are kinda ho-hum during the summer and I'd add fall and winter to that also. A nice Viburnum to check out if your looking for a BIG back of the border shrub would be 'Mariesii'. Spectacular spring bloom, decent dark green summer foliage and reddish purple fall foliage that persists for quite awhile. Its distinct horizontal branching makes it a real looker all year.

I'm one of the few that planted Viburnum carlesii for the foilage. Its course texture and blue green foilage would look quite nice with a border shrub that is fine in texture and brighter green in color.

So for what you picked, the carlesii without question.
But if summer long blooms are more important I'd pursue a Hydrangea.

'Mariesii' produces layers of horizontal branches to the ground, it needs to be in the open or at the border front to be properly displayed.

Beautybush forms a large and broad, fairly graceful mound of long, slender shoots when not whacked. Its fruits are kind of pretty and it also develops peeling bark. The main drawback for modern small gardens is its bigness, you have to be prepared to devote a significant amount of space to a shrub that is in color only during May-June.

Wow! Mariesii is GORGEOUS! I'm sold. And my local extension rates it decently on deer resistance too.

I think I'll design around that and only put a few 2-3' shrubs or perennials around it for some blooms when it's not blooming, but I definitely won't want to hide that beautiful shape.

How fast does it grow and how long does it live? Can I put in a few short-lived or moveable perennials to fill in around it until it gets big, or just mulch?

In optimal conditions, tpycially 40 years. For me in zone 5 they are a moderate grower. About 6" last year on a 3 year planted 4' B&B.

2'-3' shrubs will be plenty tall enough to hide that beautiful shape.

In my experience, double-file viburnums can easily get 15 feet across; certainly my V. 'Shasta' is that wide. So if you get one, plan to let it be the entire center of the bed and place other shrubs to the side.

Flowering specimen good standing out in stark contrast to dark background such as yew or hemlock. Definitely the wrong habit of the back of the border, unless the plants in front of it are all little things like bulbs and ground-covering plants.

Even then it might look like it should be brought forward.

Since it does not produce long branches, and in addition tends to continue flowering into the summer you might want to try Viburnum plicatum 'Summer Snowflake' instead.

I've decided that I like it enough and it gets big enough that the Maresii will be the speciman plant in the corner - planted a good 10 feet out of course - with nothing in front, and I'll build a border along the fence on either side of it (also starting a good 10 feet out from the Mariesii). The Maressii will be the big focal point from the deck and the family room window. Because of the angles we'll get an unobstructed view of the Maresii - the borders won't block it.

I'll probably put some non-aggressive flowering ground covers immediately around it for a little prettiness while it fills out.

I'll put plants that flower later in the summer, maybe PG Hydrangeas, in the borders along the fences.

Happy happy.....I love imagining my gardens in the winter....it's the only way to get through. BTW, I don't plan on doing this all in one season. I want to get the big plants started this season and will gradually fill in the borders in future years as I see how things are growing, so there will be plenty of time to change my plans based on the realities...

What did people do before the internet? I would have put in a Korean spice and been bored with it..

I have another viburnum plicatum in front that I love (it's still a baby though)....I think it's called "snowball" or something....definitely not maresii and I'm pretty sure it's not snowflake. Any idea if that will pollinate the Maresii?

I just remembered - it's Viburnum plicatum Popcorn that I have in the front of the house (planted WAY too close to the other bushes.....hmmmm...)

Glad you made a choice! I've been spending alot of time planning as well for my next phase.

I did want to speak up to your commment "What did people do before the internet? I would have put in a Korean spice and been bored with it.."....I have both the Maresii and Korean Spice, I like the Korean Spice more so than the Mariesii when not in flower.

Mariesii looks awesome in flower but the droppy green leaves are nothing special. I also like the braching silloutte of the Korean Spice over the Mariesii during the winter months. Just don't want you to write of V. carlesii in the future.

Having about 2 dozen of the many Viburnum cultivars planted here on our residential property (1.5 acres) with close up observation over the past 40 years, one needs ample space for many of the Viburnum cultivars as they obtain 10 feet or more in hiegth and width, may I suggest 'carlcephalum' or maybe better?, 'Cayuga.' Carlcephalum becomes almost tree like in size and habit yet the Cayuga has deeper green leaves, a tighter habit, also abundant blooms which have heavenly aroma, and good orange fall color. If you wait a few years, Cayaga also gets almost as big as its parent Carlcephalum as Cayuga is up to 10 feet tall and about as wide. I do not have take yet on 'Nantucket' as we have only a root cutting to put out this spring. 'Nantucket' not yet available commercially in this area; however, the reports on 'Nantucket' are full of promise. We'll see how it prospers, or not, in zone 5b (here). And, yes, we also have about 5 or 6 of the Beauty Bushes as they were already here when we arrived in 1968 to inhabit and enjoy the property. They get very tall and must be severely trimmed back about every 15 years or so to rejuvenate. The Beauty Bushes are fanatastic in the spring--real show stoppers with the cascading fountain effect of pink-white blooms and rather fragrant. Yes, they are leggy and rather common in summer yet provide marvelously good screening effect and excellent backdrop for out-in-front beds.

Hmmm The V. Cayuga down the road which has been there for at least 14 years is only 5 ft tall.

I don't know I always here about people with these massive viburnums but I never see any close to their published size or even the size that people say they have.

I have a 15 yr old Koreanspice and its only 6' tall. One guy south of me says he has a 12 footer...crazy.

Central Illinois soil is rich growing 200 Bushels of corn with a soil type only duplicated, I am told, two other places on the planet: Argentine Pampas and the Ukaraine. So, we should not be surprised that we have 10 foot tall Cayugas. Soil type is important even to Viburnums. We do not generally fertilize as these great class of scrubs as Viburnums are noted for their generally undemanding requirement for "food." They are watered in dry spells which occur occasionally here during the growing season.

I'm still waiting for that 12' pic of the Koreanspice, lol.