Halloween sales are worth £300m in the UK a year but garden centres generally concentrate on Christmas and can't compete with supermarkets on Halloween products such as pumpkins, outfits and sweets.
Retailer John Lewis saw Halloween product sales rise nine per cent in 2015.
Ahead of the 31 October event, the Halloween Christmas tree is becoming the latest trend in home gardening-inspired decoration.
With artificial Christmas trees already in garden centres, if not many other retailers, the trend for Halloween decor is coming across the Atlantic from the USA.
The 1993 Tim Burton-directed film Nightmare Before Christmas is an inspiration for spooky black trees.
But Buckingham Garden Centre's Chris Day said: "As supermarkets like Asda, Tesco and Poundland do such a good job, garden centres would struggle to compete with their silly prices."
He said garden centre displays can be low key and can be overwhelmed by Christmas displays.
Day added: "We want to get Christmas out. Seven or eight years ago pumpkins were big with us, but we don't do them anymore."
Scotsdale Garden Centre's John Ashley said: "We do Halloween a bit but Christmas is more important. We make an effort but don't go over the top."
He added that Bonfire Night is also steady but consumes staff time because fireworks have to be kept stored safely after a risk assessment.
However, some centres do have big success with Halloween events. Chessington Garden Centre in Surrey said events such as Halloween and Christmas were its best income drivers in its report on its annual results for 2015, along with catering. Its spooky zoo is sold out for the third year. The centre also holds creepy maze, Halloween circus and spooky tea events.
Retail consultant Neville Stein said he did not believe garden centres are missing out: "I don't think they are. It hasn't caught on as a major event like it has in the USA, where a huge amount of effort is put into promoting it as a 'holiday' and supporting the day with lavish events which often run over a long period of time.
"I think also the supermarkets here provide some very competitive priced halloween products and its difficult to compete with those. Putting a lot of effort into what is a one day event in the UK at this time of the year might distract garden centre owners from the real money spinner of Christmas."
A spot survey of pumpkin prices had them at 50p in Asda, 75p in Morrisons, 79p in Lidl and £1 in Co-op. Garden centre prices, for larger specimens, often start at £2.49.