You are jumping the gun. In your area I think most rhododendrons bloom in mid to late May. So wait patiently until at least until the beginning of June. It is good they haven't opened or even started opening. If you were to get a late frost it would have killed any buds that had started opening.

There are two types of buds, flower buds and foliage buds. It sounds like your big bud was a flower bud. If by June, all you have is new leaves, then here are some possible problem areas:

* Pruning. The buds are formed in late summer and early fall so pruning then or later is not advisable since it will remove flower buds. New leaf buds will form in the spring, but new flower buds won't form until the next year.

* Variety. Some plants will never bloom. Some rhododendrons that come from the seed of a hybrid plant will look good but will never produce flowers or will produce very poor flowers. To come true to the parent plant, a hybrid may be propagated by cuttings or tissue culture but not from seed. A good hybrid seedling only comes about once in a while. For that reason it is important to know that you are getting a good named variety or a good species.

* Fertilizing. Nitrogen promotes leaf and branch growth and discourages flower bud production. It can also force late season growth that gets killed or stunted by frost damage. Phosphorus promotes flower bud production and hardiness. Potassium is necessary for well being.

* Weather. Cold weather can kill flower buds. Usually you see the brown buds in the spring. Cold spells in the fall or spring can damage buds that are not hardened off. Bud blast (blooming in fall or winter) uses up good buds which are then not available at the normal blooming time.

* Age. Most rhododendrons take 2 to 3 years to bloom from a rooted cutting unless forced. Some take longer and some bloom sooner. From seeds the plant may take 1 or 2 additional years.

* Sun & Shade. Some rhododendrons need full sun to bloom and others can take fairly dense shade. In general, the more sun the more flower buds but also the greater exposure to damage from desiccation in summer or winter. More shade produces tall spindly foliage and less flowers.

Here is a link that might be useful: How to grow rhododendrons and azaleas.

Thanks for all that information! It was really helpful. The Rhodie has bloomed once in the past so I'm guessing it will bloom this year with all the flower buds presently attached. Last year it did not bloom so I'm interested to see what will happen in May.

Thanks for the information!

Heather