Most garden centres have opened or are close to opening their Christmas displays.
The Rev Dr Richard Cleaves of Highbury Congregational Church, in Carlton Street, Cheltenham, said: "The sooner you start your preparations, the more you miss the magic of Christmas when it comes.
"The message of Christmas is about God coming into a world of hardship and even violence and coming alongside people in their difficulties and being with people who find it very difficult to celebrate and have joy in their hearts.
"What I like to do is to celebrate advent for the four Sundays leading up to Christmas and then have a really big celebration."
Mr Cleaves said he would celebrate advent from the fourth Sunday before Christmas.
He said: "I wish all our businesses well because these are difficult times for them and they need trade, so I hesitate to criticise them."
The Rev Wendy Ruffle of Tewkesbury Abbey added: "It's a little early at the moment to be putting decorations up.
"The church likes to start thinking about Christmas at the end of November, when Advent starts. I can understand that there's a lot of pressure on the retailers to start early.
"But it seems to get earlier and earlier each year and from a faith perspective we like to start it for advent."
Gloucestershire County Council Conservative group political assistant Richard Coates added: "It winds people up and I think everybody hates it at this time of year.
"People always hate that Christmas gets closer and closer, but to start putting decorations up in October is ridiculous.
"To leave it until December would be a better way of doing it."
Meanwhile, garden centres are not extending the autumn planting season, with Christmas displays often taking over from horticulture in September, say experts.
Consultant Eve Tigwell said: "Christmas opening is getting earlier again. Retailers find a gap after the summer holidays in September when they are not selling much. But there is so much more to autumn than just Christmas. I’m in Denmark next weekend and their garden centres will be stuffed with autumn and winter plants. There are exceptions but garden centres need to have good plants all year round.
Tigwell said berries, autumn foliage, autumn and winter flowers and plants with interesting bark should be on display "and not just pyracanthus and skimmias."
GIMA director Neil Gow said: "It’s down to the individual business. Where they are getting it wrong are the ones shifting from summer to Christmas and ignoring gardening. I’m not saying putting out Christmas out early is wrong-it’s right because you will get sales, but don’t do it at the expense of something else. If the weather is right there is serious money to be made at this time of year and until mid November.
Gow said his Burcot Garden Centre has had cards and wrap out since August, starting a week before 2009. He opened Christmas a fortnight earlier than 2009 on 4 October "but not at the expense of gardening".
Garden Centre Group chief executive Nicholas Marshall said: "We’ve started to merchandise Christmas but are merchandising from the back. I’m old-fashioned in that I think people go to garden centres at this time of year to buy plants so grottoes and Christmas merchandise will not be the obvious first offer.
Last year 10 days of snow at Christmas 2009 hit houseplant and giftware sales and restaurants so "compared to 2009 we’re expecting better".
New Hopetoun Gardens owner Dougal Philip said: "The more interesting question is why do not more garden centres put as much effort in to their planterias as they do for Christmas."