Ipswich mum Crystal Stanley, who brought the Rainbow Trail to the UK, is asking people to put rainbows back up for the group's first birthday.
Miss Stanley created the Rainbow Trail Facebook page in March last year, after being inspired by a similar group in Italy - and was amazed by how quickly it grew.
She said: "It is incredible how the rainbow trail has grown, and we are asking everyone to put their rainbows back up on March 19 to mark our one-year anniversary."
The mum and her daughter Ariana wanted to use the symbol of hope to show their appreciation for key workers - and the idea caught on both in Suffolk and across the country, with children and adults creating colourful rainbow paintings, drawings and craft projects.
Rainbows soon adorned every village and town in all shapes and forms, and the Facebook group now has more than 191,000 members from all around the world.
And there was a proud moment last April when the project even received royal recognition, as the Queen declared the rainbows drawn by children in windows would be the “symbol” of the nation’s fight against coronavirus.
Miss Stanley said: "The group has brought so many people together, to help us all get through these awful times of the pandemic. It has done amazing things for people's mental health.
"We never expected the pandemic to go on this long, and we have definitely all had our struggles during lockdowns and made some amazing memories.
"We have raised around £5,000 for lots of charities and we will continue to fundraise for them. A big thank you to every single person who helped spread the rainbows and a special thank you to my admin team."
As well as asking everyone to put up their rainbows again, Miss Stanley said the group would be announcing its biggest competition on the anniversary, with a variety of prizes, and there would be an option for contestants to donate to charity.
An announcement on the group's Facebook page says: "To mark one year of the Rainbow Trail we would love you to get your rainbows back up in your windows to mark the occasion.
"To show we are still all together in this, to show we are still supporting key workers, to show we are still getting through this and we have hope it will be over soon. Keep safe, everyone, and let's keep positive."
For more details, search for the public group Rainbow Trail on Facebook.
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