Hydrangeas do not sprout - this is often due to the soil or incorrect care. Both the species and the variety of a hydrangea determine the time at which it sprouts.
The warmer and sunnier it was until April, the faster a hy drangea will grow. The pH of the soil can also play a role in the growth of the plant. If the plant is still very young and was planted in the last three years, it sometimes needs to take some patience.