Why have none of clarkias flowered
Clarkia need a minimum of 4 hours direct sun and cool, moist and well-drained soil. They will not flower in hot weather; they also flower better if the soil isn't rich. They should not be fertilized as this will prompt green growth at the expense of flowers. In fact, some sources say to avoid planting them near plants that fix nitrogen, like the pea family, lupine and clover. That is going overboard with caution but the idea remains. Clarkia don't flower well in high nitrogen soils. Could this be your problem or the hot weather?