Hi sokicy In early spring cut out to their bases all shoots that produced flowers during the previous year. Leave all the rest. Give some general fertilizer - plenty of potash to induce good flowering.. Also if you want to keep it blue give it some iron or you can buy a blueing agent from any garden centre. cheers skylight ps if your soil is acid your hydrangea will remain blue but if your soil is alkaline it will turn a pinky purple shade. Adding the iron will make your soil more acid.