This is the process of hardening off the soft spring growth into a rigid woody structure [preparing for winter!] and the ripening of as yet hidden flower buds for a display next spring and early summer. This is the reason we prune, if necessary, the spring and early summer flowering shrubs immediately after they have flowered. Only prune June flowering shrubs if they really need it and most of the time you'll find that they don't. Astronomically the summer solstice is the beginning of summer , Hurrah to that.

Source: Irish Independent June 21, 2019 10:30 UTC