User blog comment:Songuyenca/Tip to make money at lower level?/@comment-5042346-20120604184156/@comment-5051663-20120606051755

Pink and Yellow Starflowers (now available for a limited time) yield 20 coins/hour/square (better than Playgrounds, worse than Venus Fly Traps) but they have an awesome payback time of 5 hours! (Compare with 2 days for Playgrounds or 16.7 days for Venus Fly Traps).

If you invest 1000 coins to buy 10 starflowers you can buy 2 more per hour with the taxes from the starflowers indefinitely. Keep up the reinvestment for 16 hours (you gotta sleep sometime ...) and you'll have 184 flowers (if you've got space to fit them) producing 3680 coins/hour.