Fewer than 100 registered entries competed in this year’s event and without a "significant increase" in numbers the competition may not continue. The event drew over 600 entrants in 2009.
"Over recent years the number of entrants has dropped, and we are urging people to show their commitment to next year’s competition," said Councillor Mark Lygo.
The board member for parks and sport said: "Oxford in Bloom celebrated its 25th year this and it would be great if we continue this celebration for another 25 years.
"But we cannot continue with this ceremony if we don’t get the support from the community. There are many ways of getting involved from joining the committee, entering your garden or raising awareness of the competition."
Oxford in Bloom rewards the best-of in categories such as most florally attractive gardens, containers, commercial properties.