Recommended Ways to Earn GP

You should definitely do all the daily quests. You can get at least 200 GP per day for sure. Don't forget to send GP to your friends either. Your GP doesn't decrease when you send it, and you're more likely to get some back if you send it. Also, don't forget to water plants every day. You can get GP randomly by watering, and there's no limit to how much you can receive, so you should water as much as you can.