Ok so this is for ipad 4th GEN and I don't know if it works on any other device
1) go to your app and plant something expensive
2) close the app and double tap the home button and delete the app from history
3) go to settings and turn on airplane mode
4) go to general/date&time/change the month to either April or may
5) open your sims app
6) close the app and turn on your wifi( do not turn off your airplane mode)
7) open yor app and go collect the money from your plants