I'm using v1.2. I attribute the longer time to the fact that all my plants were wilted and I check the max health box. So for each plant it had to water twice, apply 2 heals, 2 poisons, sometimes a cure, and 2 strengths. When the plants are vibrant, I expect it to take closer to 50 minutes. I'll post the stats when my plants recover. This script is awesome!
Edit:
My plants are vibrant again. Here are my results...not sure if the bmp will show up
1579 plants in 1 hour and 13 minutes