…that I heard about recently?
I think the main theme is to indicate God’s love for us. However, not having a rose does not mean God does not love us.
In many cases, people ask for a rose for some confirmation in their prayer. For example: a person was praying for a job and with this job she might be able to serve Him better. She asked her to send a rose to confirm that the prayer was indeed pleasing to God. The Saint sent the rose for that confirmation, and a month later, she got the job.
Note: don’t use “rose” as a sole indicator in your prayer. God grants you your prayers without giving you any roses many times.
its a novena (i think you can find it in the peita book still, great devotional) that by the end of the novena you are supposed to recieve a rose if the prayer has been granted. they say that it’s unfailing, but i think that prayer and the spiritual life is a little more complicated than that. most of our prayers (in my experiance) are rarely answered in the ways that we had in mind. praying with confidence in the goodness of God and trusting in His ways are the basics of prayer- though it is nice to know that heaven has heard you when you recieve that rose.