Visually, I'm really impressed. I also think there are some useful mechanics that could be explored in a larger games. I would prefer it if
- growth rolled over between cycles so that fertilizer wasn't only useful at very specific values
- the fertilizer and water logic was fixed so that they can't both be toggled at the same time
- the scrubbing was tightened up a little
Otherwise it's just a matter of creating different scenarios so the player is left to try to optimize the plant growth and this would be a really fun little game!