In ancient times these plants symbolised new life. They grew berries which were the seeds of new life at the time of year when most things looked dead. In pagan times people decorated their homes with these berries because they looked very pretty and offered hope for the spring. Christians kept the old customs of decorating their houses with these berry plants but looked for Christian meanings in the plants.
Ivy is the sign of friendship which is to remain strong and true for years. It was brought indoors at Christmas as before in the mid-winter festivals because they are traditionally a time to remember and renew friendships.
Mistletoe is brought indoors because of the old belief that people who meet under the mistletoe will remain friends for a long time, and enemies that meet under the mistletoe will stop arguing and become friends.
More recently mistletoe is hung over doorways, and to be kissed under the mistletoe is good luck.
The people who lived in northern parts of the world believed that fairy folk lived in evergreen trees. When the weather was at its worst at the time of the festival of the shortest day they would bring branches of greenery in to protect the fairy folk from the cold weather.
Decorating homes with evergreens was one of the earliest form of decoration known.
Again, linked to very ancient times the candles were a symbol of light and linked to festivals as a promise of sun...therefore spring and the growth of food. Christians linked candles to Jesus Christ and the light symbolised his life, love, teaching and death. Hindu people have a festival of light called Diwali, Jews have a festival of light called Hanukkah.