Question
2 doublefile viburnum bushes that I planted 2 years ago are growing well this year. But neither one flowered this year. The leaves look healthy. They both receive about 4 hours of sun a day, maybe a bit more. Why no flowers this year? It was a very cool and wet spring and early summer here in southern NH. But where they are planted drains pretty well. Might you have any ideas why they don't bloom?

Answer
Carol,
There are 2 reasons that I can think of that would cause viburnums to not flower.
Pruning at the wrong time of the year- early or late in the season after the buds have been set up on the plant. The best time to prune or cut back any flowering plant is right after they finish flowering.
The other reason is if they are being overfertilized with high nitrogen fertilizers. Nitrogen promotes leaf and twig growth over flower production. I do not know if you are fertilizing twice a year, but if you are, cut back to one fertilization in the fall using a low nitrogen fertilizer.
A technique that is sometimes used in apple orchards to promote flowering of the apple trees is root pruning. The roots of the plant are severed approximately 1/3 to 1/2 of the distance from the trunk. this places the plant in stress and causes the plant to set up buds for flowering to help replace the lost nutrients. This is a radical technique that I would recommend as a last resort.
If I come across any other causes I will let you know you.