Don't use a graded color scale for this, but create two "classic" rules.
Set the fill color of the range to 'No Fill'.
On the Home tab, click Conditional Formatting > New Rule.
In the Style box, click Classic.
Under the Classic box, select 'Format only cells that contain'.
Leave the first drop-down set to 'Cell Value'
Select 'less than' from the second drop-down.
Enter =0 in the box next to it.
Click Format...
Activate the Fill tab.
Select red.
Click OK until the dialog boxes are closed.
Repeat these steps, but with 'greater than' instead of 'less than', with =0.1 and with green as fill color.