Gold is the essential currency in Pocket Harvest, and allows you to buy crops, unlock land and new facilities, obtain a higher ranking, and do investments in your city.
While making gold in the beginning of the game is a little difficult, Pocket Harvest has an easy way to get hundreds of millions of gold in middle or late game.
The strategy is as follows:
A beginner fruit can be strawberry, or apple in Pocket Harvest. You don't need to increase fields or yield much, but you will need to upgrade the crop multiple times, to a quality high D or C.
To successfully upgrade your fruit, you'll need two farmers who have a high knowledge, roughly 90-100 to begin with. Alternate using these two farmers on increasing the quality of your fruit constantly.
While increasing the quality of your fruit, pick a single spot on your map where the fruit has the best fertility, appeal and environment to maximize its quality. Make sure to make at least a 2x2 of this fruit to boost appeal.
Now that you have a better quality fruit (grade C), enter the local and national fruit contests with that fruit.
You will need at least 100 to win the local fruit contest, and a few hundred in quality to win the national fruit contest.
After you win the National Fruit Contest, you will unlock the most lucrative crop to grow, the melon! A melon starts at about 6000 gold, and a single upgraded melon can yield more than 15,000 gold!
You will need to invest and upgrade the melon quite a bit to get to the high end, and it's important to constantly cultivate the yield as well as the quality of your melons.
Outside of cultivation, you will still want to maximize the price of each sold melon. You can do this by adding decorations like bamboo, flowers, hills around your melon patches. Make sure to plant in patches of 2x2.
In addition, you will want to make sure melons are cultivated optimally, meaning plant as many melons as you can, ideally in prime locations with robots close by or farmers to cultivate. Add a sprinkler to decrease the watering load, or use items like the Moist, Mach, Growth and Bumper cards to manually get a boost in revenue.
Finally, winning the local, nation and world fruit fairs with the melon will further boost the price of your melon. Since you should be investing in quality anyway, this part should be a breeze. You will need several hundred quality points to win the National Fruit Contest.
Melon is the absolute best crop in Pocket Harvest to get lots of gold. To unlock you will have to win the national fruit contest early in your game, and then cultivate both the yield and quality of melon. Afterwards, you will be swimming in hundreds of millions of gold in no time!