That question depends on area to some degree and can change literally just down the road! Plus can be totally off if your in range of a specific agricultural crop. Then add in weatherI’m Surrey/Berks boarders so not that far, main summer flow can start beginning of June with bramble. Mid June limes will start with flowering and different types into early July. The first sweet chestnut normally starts beginning of July and is mainly done by the third week in the month. That pretty much sums up my summer in this area. Then chuck in weather rain or drought that can affect the various flowering periods.