If you plow empty land you will gain 1 Experience point but lose 10 coins. Sell the plowed land to get the 10 coins back while keeping the Experience. Repeat this as many times as you desire. Note: this trick will be less effective in later levels because of the low amount of Experience gained.
To perform the following cheat you must first exit the game. Then go to 'Settings' followed by 'General' and finally 'Date and Time'. Advance one day and then resume the game and check your daily surprise. If you do not get a brain you will get gold. The amount of gold depends on how many of your friends also have Zombie Farm.
First, plant a crop. Then, exit out of the game and go to settings, general, date and time, make date and time, then change the time ahead how many hours or minutes the crop should take to grow. Last, go back into the game and the crop should be fully grown.
You can not wait after the crops are grown for a day, for example, potatoes and so on to go to the general setting and change the date to the day after returning to the game and harvested crops, it's as simple as that