To upgrade your Farm, click on the new upgrade button. It's located on the bottom right-hand side of your screen, next to the Inventory button. 
The Upgrade Menu shows all of the upgrades that are currently available and the requirements needed to unlock them. 
Note: Not all upgrades are currently accessible. Some upgrades require a certain level or other upgrades to advance. Click on any upgrade to see what requirements you need to fulfill in order to unlock it. 
A - The list of upgrades and the level required to unlock them. 
B - Use this bar to scroll though all of the available upgrades. Click on “Upgrade View” button to see what items on your Farm are upgradable.
C - A list of the perks an upgrade will provide you. In the image above, you can see that upgrading to a Field will provide more Crops, faster mastery and more Prize Crops. 
D - The number of Coins and Favors required to unlock an upgrade. 
E - Use this button to purchase your upgrade once you have completed all of the requirements. 
Big Harvest is all about allowing you to explore the endless potential of your Farming creativity. In order to really unlock your full farming potential, we recognize that many of you need more space. Our answer to this problem is Fields. Fields will allow you to plant more Crops, master your Crops faster, get more Prize Crops,  and save space! One Field is the equivalent of 5 plots, but it only takes up the space of 4. 
Before you can use a Field, you have to build one. If you reached Level 25 or above, you can select Level 1 Fields from the Upgrade menu. Once you have selected the field, place the construction frame on your Farm.
Note: If you place your construction frame on existing plots, we'll harvest these plots for you and refund any Water, Fertilizer and Coins you have spent.
After placing the construction frame on your Farm, you have to wait for the Townsfolk to help you finish building it. If you want to see how long you have to wait until the construction is finished, you can click on the construction frame.
Note: If you don't feel like waiting, you can skip ahead with Farm Bucks. 
Once the timer is done, click on the “Finish Now!” button to let the Townsfolk complete the construction.
Before you can use your new Field, you have to put 5 normal plots into the field construction. Click on the “Tools” button in the bottom right-hand side of your screen, and move 5 plots into your field. Now, your new field is ready to be used!
Note: When you unlock Fields for the first time, you can purchase up to 5 of them for your Farm. You have to purchase each of these Fields individually (you will not recieve 5 level 1 Fields in a single purchase).