To change your Apple ID login follow the steps below:

1. Go to the "My Plants" tab
2. Tap Settings (gear at the top right corner) 
3. Tap "Account" 
4. Then click on "Password" 
5. Verify by logging in to your Apple account and enter a password for the account. 
6. Tap on "Email" and change the email adress to the one you want to use. 
7. After this is done you will be able to login using the email option. 

Sometimes you may want to share the plants and care schedules in your account with someone else. To be able to do that, your account must be connected to an email and password.