Rain, Organic Fertilizer, and Faster Farming are the three speed-up options for your crops and trees.
You’ll find them in the Speed-up tab in your Shop.
Rain & Organic Fertilizer deal with speeding up the growth time for crops and trees, while Faster Farming is for —you guessed it— farming.
Generally, we can say that Rain is best to use if you have a large farm, while Organic Fertilizer is suitable for smaller farms with fewer crops and trees. But in the end, it all comes down to personal preference.
Faster Farming (the two green arrows) enables 70% faster farming (planting, harvesting, feeding animals, loading machines, and collecting produce) for a specific period of time — depending on the option you choose.
You can permanently achieve the same effect for crops with the Mastery feature. Then, you will be able to plant and harvest your crops in 0.3 seconds instead of 1 second.
Faster farming DOES NOT reduce the growth time of crops. It only helps you plant, harvest, collect and load machinery and produce in 0.3 seconds instead of 1 second.