People in the seventeenth century were more likely to refer to religious feast days and quarter days than dates. So Grammar Schools commonly defined the summer as running from Lady Day to Michaelmas rather than 25 March to 29 September.
The quarter days were particularly important because they were commonly the days on which rent was paid (and in the world of commercial property, this is still the case today). The quarter days are Lady day (25 March), Midsummer Day (24 June) Michaelmas (29 September) and Christmas Day (25 December).
For servants, Lady Day and Michaelmas were important because these were often the days on which they were paid: there was no handing out of a weekly or monthly pay packet.
So re-enactors need to become familiar with the feast days that would have applied in the seventeenth century.