The Ogham Grove is formed of the twenty traditional ogham trees placed in their correct sequence. Yew is in the north for Winter Solstice; Ash is in the east for Spring Equinox; Apple in the south for Summer Solstice; and Elder in the west for the Autumn Equinox.
Beltane is the last of the three spring fertility festivals, the others being Imbolc and Ostara. Beltane is the second principal Celtic festival (the other being Samhain). Celebrated approximately halfway between Vernal (spring) equinox and the midsummer (Summer Solstice). Beltane -- Holiday Details and History - Witchvox Articl