Context is everything. If I turned that in as a serious project at work, tell me all the ways it was less than perfect. If a 9 year old brings it to show and tell, you explain how much you liked the cool parts.
If my florist handed me a dead flower, I'd be irked. If a 4 year old hands me a dead flower saying "I picked this for you!", I'd tell them what a beautiful flower it was and how much I appreciated the nice thing they did for me.
A 9 year old isn't a 4 year old, but I think you get the gist.
I would also encourage the kid as much as possible, but I'd be doing them a disservice if I didn't also take the opportunity to teach them about the basics of keeping flowers alive in transit.
If my florist handed me a dead flower, I'd be irked. If a 4 year old hands me a dead flower saying "I picked this for you!", I'd tell them what a beautiful flower it was and how much I appreciated the nice thing they did for me.
A 9 year old isn't a 4 year old, but I think you get the gist.