The routes have been tagged to suggest the time of year they can be run. This is based on potential overgrowth.
Tags are:
Spring - March Equinox (20th March) to June Solstice (20th June)
Summer - June Solstice (20th June) to September Equinox (22nd September)
Autumn - September Equinox (22nd September) to December Solstice (22nd December)
Winter - December Solstice (22nd December) to March Equinox (20th March)