Vincent said he found them complex, half-living and half-dying, and thought it would be a challenge. After falling in love with Amy and being shown how beloved his paintings would be in the future, he decided to reconsider her suggestion, and actually painted it.
The painting was on display in a section of Musée d'Orsay dedicated specifically to van Gogh. As they were just leaving the museum for the third time, the Eleventh Doctor and Amy noticed the painting, and Amy was reassured greatly by the fact that they did, after all, at least change something in his life. (TV: Vincent and the Doctor)
Behind the scenes
Still Life: Vase with Twelve Sunflowers was painted several times by van Gogh in the last couple of years of this life. The one featured in Vincent and the Doctor is a replica of the third version at Neue Pinakothek in Munich, Germany altered with "for Amy" painted on the vase.