After she started dating Prince Harry, she posted Instagram photos of a stunning bouquet of pink and white peonies, captioning it: "Swooning over these. #London #peonies #spoiledrotten".
In 2016, the American star wrote of a bouquet of the delicate fragrant blooms: "I bought these peonies for myself yesterday because they make me so endlessly happy.
"Do something sweet for yourself today too. #treatyourself #simplepleasures #favoriteflowers."
On her now deleted Instagram account, she also frequently posted images of light pink, peach, and orange roses.
And showed how she made mini arrangements of hydrangea in jars around her house.
Such is Ms Markle's love of flowers, the couple's lemon and elderflower wedding cake - by Claire Ptak, owner of the east London Violet Cakes bakery - will also be decorated with fresh spring blooms.
Her mother Doria even has a floral nickname for her.
"My mom has always called me Flower," Ms Markle revealed in 2014, adding that it was her nickname "since I was a little girl".
Harry himself has been involved in two award-winning gardens at the Chelsea Flower Show.
In 2015, designer Matt Keightley created a garden for Harry's charity Sentebale and won a silver-gilt medal.
It was inspired by the vibrant atmosphere of a children's residential camp set up by Sentebale in Lesotho, southern Africa, to help youngsters with HIV and Aids, and featured wooden walkways set among mature trees and abundant foliage.
In 2013, Harry's Sentebale Forget-Me-Not garden at the show in London was created by landscape gardener Jinny Blom.
It was inspired by the prince's experience of loss over the death of his mother, Diana, Princess of Wales and featured a pattern based on hearts and crowns, cut into a floating stone in the middle of the garden.
Blom, who warded a silver gilt medal for the design, said of Harry at the time: "He's very involved and, so far, has been very happy about everything I'm doing... He is very excited about it. He trusts me.
"But, at the end of the day, he's a soldier, not a gardener."
When the Duke and Duchess of Cambridge wed in Westminster Abbey in 2011, an avenue of eight potted trees, some as tall as 20ft, lined the aisle leading to the altar.
London-based Shane Connolly was the artistic director of flowers for the royal wedding.
The colour scheme was white, green and cream, and Kate decided upon euphorbia, a green shrub with yellow blossoms, white lilacs, magnolias, and lily of the valley.
Kate's choices were inspired by the language of flowers, a communication method in the Victorian era when flowers were used to send coded messages to express unspoken emotions.