Entertaining premise..
..damn aliens, always taking our weed.
I love when games like this come to Newgrounds because you can then tell who knows the basics of weed and who doesn't..to wit, you can tell the kiddies because they're the ones writing reviews for this game and Marijuana Crop Duster with things like "I don't get it, this sux, how come I can't find the weed?"
(For the confused: in this one, you're _tending_ your _crop_, genius.)
Anyhow. You might want to consider having the plants grow at different rates, maybe speeding up more towards the end of the time limit, otherwise one just ends up protecting two or three lone stalks whilst sacrificing the rest to the aliens. Damn aliens.
--Jenner