From LearnReligions.com

As the year comes to a close and Samhain approaches, the Ivy moon rolls in at the end of the harvest season. Ivy often lives on after its host plant has died — a reminder to us that life goes on, in the endless cycle of life, death and rebirth. The Celts called this month Gort, pronounced go-ert. This is a time to banish the negative from your life. Do workings related to improving yourself, and placing a barricade between you and the things that are toxic to you. Ivy can be used in magic performed for healing, protection, cooperation, and to bind lovers together.

From Ireland-Calling.com

Ivy has many superstitions and beliefs attached to it.

Because it had the ability to form dense thickets in woodland, grow where other plants could not and block out the light from even the mighty oak, ivy was believed to be very powerful by the Druids, more powerful than its enemy, the vine and quite sinister.

The ivy and the vine have been seen as enemies since ancient times. This seems odd since the same Greek and Roman gods are associated with each.

Bacchus, god of wine

In Greek mythology ivy was sacred to Osiris and also associated with Dionysus. In Roman mythology Ivy was connected to Bacchus, the god of wine as it grew over his home land.

Bacchus is often portrayed wearing an ivy crown, perhaps because this was once thought to prevent intoxication. The poisonous berries of the ivy, when ground into a powder were also once believed to be a hangover cure.

The link between Bacchus and ivy was taken over to England where old English Taverns would display ivy above their doors indicating the high quality of their drinks.

The proverb ‘Good wine needs no bush’, meaning good wine speaks for itself, comes from this practice.

Gort, G –

Ivy, a symbol of strength and determination to the Druids, is the twelfth letter of the ogham alphabet, gort, and the eleventh month in the Celtic tree calendar, representing September 30th to October 27th.

Protection from evil

In old Ireland ivy was thought to provide protection from evil when growing on or near to a dwelling.

However, if it should die or fall down then misfortune would fall upon those therein.

Ivy was often carried by young women for good luck and fertility. Used at weddings intertwined with holly, the ivy would symbolise fidelity and at Yule-tide, would bring peace to the household.