Spring bloom is the most anticipated thing in a yard and the least reliable, and both facts have the same cause: it happens at the edge of winter.
An early flowering plant can open ahead of the last hard freeze and lose the whole year's display overnight. That is not a defective plant and it is not bad luck — it is placement. A warm week in April convinces the plant that winter is over, the buds open, and the frost that follows takes them.
Which means exposure does more work than species choice. The same variety on a warm south or west wall breaks dormancy early every year and gambles. On a north or east exposure it stays cold longer, opens later, misses most frosts and flowers reliably. Putting early bloomers on the cold side of a property sounds backwards and is the single most useful thing to know about them here.
The other half is pruning, and it costs more flowers in this valley than frost does. Spring bloomers set their buds the previous summer, on last year's wood. Prune in late winter or early spring and the flowers come off before they ever open — the plant is perfectly healthy and simply never blooms, which is exactly how it gets diagnosed as a bad plant. They get pruned right after they finish flowering.
