I bought a Little Joe viburnum to pollinate my Blue Muffin for better berries. Was very disappointed that Little Joe is done blooming and Blue Muffin is still in bud stage. Will bloom time vary from year to year? I have read on numerous sites these two dentatum are supposed to pollinate one another. Any insight would be appreciated. Also just planted a Brandywine to pollinate my Winterthur. Hope I have better luck.
As you are obviously aware, most viburnums need to have another cultivar planted in close proximity for good fruit display. Both the Little Joe and the Blue Muffin are classified as V. dentatum - and both have a listed bloom time of May-June. For your Blue Muffin, cultivars of Viburnum dentatum like Autumn Jazz or Chicago Luster may improve your fruit set. Winterthur, V. nudum will often bear some fruit without another variety/cultivar nearby. Your Brandywine is also V. nudum so should work, otherwise consider a cultivar such as Count Pulaski or a closely related cousin, V. cassinoides.