Hello, kaliszek. I assumed that your plants are planted in the ground, as opposed to being grown in a container.

I would recomment that you re-visit the basic requirements to see what could be missing. (1) The more sun they get, the more flowers shrubs produce. Are they getting between 2-4 hrs of sun over there minimum? (2) Rhodies produce flower buds starting in July (approx). Are you pruning them in or after July? (3) Constant moisture assures that the plant is healthy while producing and keeping these buds. Are they drying out during the critical bud-forming months? (4) the soil should drain well and be acidic. Any draingae issues where these plants are located? Is the soil clay? (5) I could not tell what zone you live in. Do you apply some winter protection techniques? To protect them from the cold and drying winds? (6) wild temperatures fluctuations can also kil the flower buds. Have you experienced warm temperatures followed by sudden freezing temperatures? (7) Rhodies planted out of zone may be able to prosper but bloomage would suffer. Are the plants good in your zone? (8) Some old rhodies have to be pruned to revitalize the flower show. However, you said yours were "smallish". When did you plant them? (9) Rhodies planted from seed will not flower for a few years. Did you buy your plants at a nursery or grow them from seed? (10) Some pests out there like to eat the flower buds? Do you have deer or squirrels where you live? (11) Have you done a soil analysis ever? It would be nice to ck your Ph Level and the availability of minerals in case there is a problem. (12) How much mulch do you have on these rhodies? About 3-4" protects them during winter and keeps the soil evenly moist.

I am sure there are many more possibilities in addition to these. Do any of them fit your situation, kaliszek?

Luis

Kristine, how much sun are they getting. The first reason in order of why blooms are low in numbers is too much shade. Shade or protection from mid day sun can be necessary in warmer or more southern parts of the country...not so much here where many of the larger leafed rhodys can handle full sun.

Are they smallish because they are young or newly planted? It can take a few years of establishing root and framework before they bloom fully.

Over-fertilization can lead to foliage growth while inhibiting blooming.

Add failure to deadhead (which doesn't seem to be the issue with yours :)), pruning too late in the year, drought during the latter part of summer when they would normally be setting buds for the next Spring.

Do you see anything here that might apply to your own? You may occasionally buy a rhododendron that just is not ever going to bloom well, but it's not likely you would have 'a few' like that in one garden.

You received two excellent postings. A couple additions.

If you live in the Mediterranean climate in Washington, then the summer dry spell can be preventing flower bud formation. Some supplemental watering during the dry spell can assist flower bud formation.

If your soil is deficient in nitrogen, phosphorus or potassium, then this will prevent flowering. Normally, nitrogen is not a problem if the leaves are a good green color. In fact too much nitrogen is more of a problem. If you do fertilize, use a good fertilizer like Holytone and fertilize once a year at most, and then fertilize in the spring with only half of the amount recommended on the package.

If your plants came from seed, they may never bloom. Some natural hybrids or even intentional hybrids never bloom. The sure way to get a blooming plant is to either use a plant that came from a cutting of a good variety or from seed from a species that is growing among its peers.

The most common causes for a lack of bloom are too much shade or pruning too long after the normal blooming time.

As you are probably picking up from above posts more background information on these particular specimens is needed to zero in on what their problem is.