[seszett]

Very nice, I could suggest two more factors influencing growth that are important for plants: geotropism and phototropism.

Geotropism basically makes plants grow away from the source of gravity, and phototropism makes them grow towards light (and that is usually reversed for roots).

[seszett]

To OP, I don't know why but you're apparently shadowbanned, and your comments appear "dead" even after vouching for them.

Probably an automated heuristic, you might want to send an email to mods so they can reverse it.

[solarkraft]

I vouched too, the two comments seem restored now.

[dnmc]

Oh, those are great ideas. On that note, I was also considering simulating nutrients and rewarding the roots that find them.