Three weeks ago Prince Christopher informed Lexi about the white flowers that his mother planted and wanted to use for the marking ritual. Queen Yvonne is not a werewolf and the concept of a wedding ceremony is quite important to her that's why she instructed Lexi to make it as grand as possible.
Fortunately, the former queen's garden has different kinds of white flowers that she could use in the aisle and altar for the goddess of the moon during the marking ritual. The plants didn't have flower buds yet when she came to the gardener and was advised to come back three weeks later to see if the plants would grow flowers for the season.
"My lady," greeted the old gardener. "I was planning to go to you if ever you will not come back. I have good news for you. The plants are starting to grow buds and are just perfect timing for the occasion. They will surely bloom two or three days before the ceremony."