How to check if the date is greater than today's date Laravel5

I have a table where there is a column which has event date

but the column is of type varchar.

The date is saved in form of dd-mm-yy

now I want to get all the events whose date is greater than today's date.

My code which doesnot work looks like this

$cat=Event::where('date','>=',date('d-m-Y'))->get();

But its not working it is getting me all the events

Any help would be appreciated

Thanks

via Chebli Mohamed