You should add bugs, weeds and possibly flowers to make this more complicated than just doing a boring job of waiting for plants to grow. Bugs would work like this:
Bugs
Once you get to the second or third stage of growth, bugs will begin to go on your plant. There will be bees, wasps, ladybugs, caterpillars, yellow jackets, spiders, black widows, butterflies and aphids. Click your plant to see what bugs are on your plant. Bugs will have info on them and some might attack you.
Bees: They're probably hanging out or pollinating. You can check for hives. Best not to harvest while they are on it. (Give them a 25% chance of attacking you if you're harvesting while they're on it.)
Sting Damage: 4 and bug goes away.
Wasps: Like bees, they're probably just hanging out except they won't pollinate. Unlike bees, they can sting you up to three times. Strongly recommended you leave them alone. (Give them a 50% chance of attacking you if you harvest with some on it.)
Sting Damage: 4 and bug can attack additional times then goes away. (If they sting you, gives a 25% chance they'll do it again, then a 5% chance they'll do it again.)
Ladybugs: Whoa! These
dudes dudettes eat aphids. Best not to kill bugs while they're on them. They will help you on your plant and won't even attack you! (Eats aphids on your plant.)
Caterpillar: They might look cuddly, but they're actually eating your plant! Remove them! Some will turn into butterflies which will attack flowers.
Poisonous Caterpillar: Crap. Can't remove these guys without being poisoned (damage). Might have to risk using bug killer.
Poison Damage: 10, works like a sting.
Butterfly: Not made out of butter. They will go to your flower and eat the pollen which makes bees useless.
Yellow Jackets: These aggressive bugs will sting you right as you notice they're on your plant! Ouch!
Sting Damage: 10. Bug might not go away and could go to a different plant.
Spider: They eat bugs including ladybugs, they could attack you for harvesting and destroying their web. (50% chance of attack.)
Bite Damage: 15.
Black Widow: Eats everything, even the things you love (Ladybugs). WILL attack you for harvesting.
Bite Damage: A whopping 45.
Aphid: Oh, god. Get a ladybug here now! They come in groups and will eat your plant.
Weeds
Weeds kill your plant. Just kill them before they do. You might want to add an item or something that lets you kill them.
Flowers
I suggest flowers too. I'm guessing you could make them a second source of making money and using them for bees. Bees will (of course) spread the pollen from the flower to other flowers and plants which will boost their growth. Keep bad bugs off of them, though.
Is my idea okay? Please comment on it.