App exited unexpectedly
Flower Garden is a fairly memory-intensive application. If it exits unexpectedly to the iPhone dashboard, it probably means your device is running low in memory and needs to be restarted.
Press and hold the Sleep/Wake button for a few seconds until the red "slide to power off" slider appears, then slide the slider. Then press and hold the Sleep/Wake button until the Apple logo appears.
Launch Flower Garden again and it should work fine again.