During the Middle Ages, May was traditionally a month held to be in honour of the Mother of God. Statues in churches would be decorated with flowers, and acts of devotion made.
Although for us Orthodox, August is traditionally a focus of devotion to the Theotokos, with the Dormition Fast and the associated Paraclesis, there seems no reason why May could not also be a focus of special devotion to the Blessed Mother of God.
Information about the history of May Gardens can be found here :-
including information as to how to set up your very own May garden in honour of the Blessed Virgin.