Thanks for such a well-written explanation! I purchased viburnum trilobum compactum plants from Forestfarm several years ago-- and although they survived for ten years or longer, they never did anything. Now I understand why they never produced fruit . . . but actually, they barely even bloomed! I finally gave up and pulled them out this spring. Very disappointing. As to why plants of different provenance bloom at different times even if they are of the same species, maybe you could think of it this way: every species has some genetic variability within the species. A group of specimens growing in a certain area would tend to produce seedlings that bloomed at several different times. However, the seedlings that bloomed at the best time for that location would have a natural advantage over the seedlings that bloomed a little too early, or a little too late. Therefore, by natural selection, the bloom time that is best for the area would eventually become the most commonly found genetically-programmed bloom time amongst plants in that area. In other words, the gene pool of seedlings in that location would have been narrowed. Similarly, seedlings from a different part of the country would slowly narrow their genetic pool to reflect whatever bloom time is best for their location. When you then order plants from the two different locations, even though you are now growing them in identical conditions, their bloom times will continue to be influenced by their genetic programming as well as their current growing conditions-- and this will be true for as long as those two plants live, even if they are growing side-by-side. Does that make sense? I realize that I'm not explaining it very clearly. :( (Maybe another way to understand it is to think about humans: we are all one species, but we look a lot different according to our ethnic backgrounds because when groups of people were isolated geographically from other groups, an unusual or recessive trait-- red hair, for example-- had the opportunity of becoming very common within that specific isolated population.)

Are you concerned with berry production? If so, you need a different clone of the same (or a closely related) species that blooms at the same time. For example, V. dentatum 'Blue Muffin' will need a V. dentatum 'Red Feather' or a V. dilatatum 'Cardinal Candy' will need another dilatum clone. They can be some distance apart--50 feet maybe or more.

Viburnum fruit are quite edible (at least the ones that can be grown in the midwest that I've consumed) though they aren't all very tasty. Birds will most likely clean up all the arrowwood fruit soon after they ripen, so worrying about kids/fruit shouldn't be a problem. Rachel: get a compact V. carlesii in addition to the V. x juddii, and you should have appropriate partners for future fruiting. As far as what people should know: I've been a horticulturist about 20 years, and a landscape architect (including school) for about 10. I can't claim to know everything, but I darn sure try to learn it when it's obvious that I don't and need to. Same with this instance. Learning all the viburnum lore came with first attraction to the possibilities of the genus, and then the need to make all the possibilities happen when the plants were acquired and planted. I had the advantage of many years of acquiring texts on woody plants, so a little reading got me steered in the right direction. Not every plant/design professional is so oriented (unfortunately) and sometimes only is exposed to the knowledge level of those they work with, or the limited amount of information that can be provided during the short time in school. I admire, and look for in those I work with or hire, that thirst for CONTINUING LIFELONG EDUCATION (of which GW is one additional source) which illustrates a passion for higher standards and results. It is promising that the landscaper you admire bothered to source more info for you. It is not promising to suggest that you are overthinking things. I'd be interested in hearing what "tons of viburnums" she plants; what clones of which species; and what happens when she only plants one clone of a species that is rarely represented in Chicagoland. There is the rub. To make the point, you also might ask her if it is overthinking things to only plant Ilex verticillata Winter Red, and no male pollinator, especially if you are in a relatively isolated locale. I bet the various clones of V. dentatum are well represented around Chicago, since several of them were selected there and have been planted for years. Not so with quite a few others though, like V. nudum Winterthur. You may NEVER see fruit on this fine plant without a dissimilar V. nudum around, since it blooms quite a bit after almost every other common viburnum species. So.......you are on the right track, and hopefully have many more viburnum experience opportunities ahead. And, if you've helped a design/landscape professional learn a little something along the way, the world will be a better place for it.

Just a comment: Viburnums are great shrubs. But if you are in certain areas of the east, do be on the watch for Viburnum leaf beetle, yet another new import that is decimating especially arrrowwood Viburnum in these areas. The good news is that it's super-easy to scout for the egg masses at this time of year, just before the plants leaf out. The egg masses are easily seen and can simply be scraped off and taken out of the area. The female will have laid them on twig ends. My state has recorded a couple sightings of this insect, to the south of where I operate. So I still went ahead and planted some arrowwoods for a recent project. One quick visit in early spring has assured me-and I expected this-that no Viburnum leaf beetles are present.