Make sure you are in the applicable season. When you create a new crop, the crop will be created only for the season you are currently in. The current season is selected in the top right corner of the page.
Go to the Settings page by clicking on "Settings" in the sidebar navigation.
Select the "Crops" block. You will be redirected to the list of crops.
Click the "Create Crop" button located at the top right of the page.
Put in the name of the Crop.
Click on "Create Crop" to save the new crop under the season you are in.