I guess this is about all I will get this year from Silene kantzeensis... it bloomed more heavily last year.
i guess in theory we hope to keep garden conditions more consistent from year to year than they are in the wild, but weather must still affect performance...
the difference in wildflowers from year to year is striking, and not always what you'd first think: this year being so much drier than the last couple, some plants are much smaller and less floriferous, others still have a lot of flowers, but the plants overall are thinner or smaller; other plants (esp woodland plants) here are much more vigorous and floriferous this year--i'm guessing because of heavy and late snowfall, which both watered the forest well, and kept plants protected from winter spring drying...
and of course your silene may have completely unrelated reasons for not flowering as much this year