my euphorbia is not blooming

They should be chopped back after flowering to encourage new growth to form (from which they flower). The trick with euphorbias is to hold back the watering or improve their drainage or both, they are much happier in situations where we might ordinarily add water. Another reason for them not flowering is the light levels where they're located. Wulfenii requires heaps of bright sun.

Euphorbias flower on the shoots grown the previous year, so only cut off the old flowered stems in summer or when tatty. Cut each one off right down to its base but don't cut any that didn't flower.