Make a new garden, then buy 3 venus pinata traps.
After you've done that wait for them to grow, after it's done hit it with your spade until the flower falls off, along with 3-4 seeds.
Sell all but 1 seed from each plant and do it again and again, I've gotten $40,000 in 15 minutes by doing this.
Plant the seeds in holes from your shovel to make them grow faster.