Display 'Date' cell as blank instead of default year 1900

[charger100]

Three columns.
A - Date last checked
B - Due Date
C - Actual Date checked

Currently column B is formatted to Date and simply has =A+84 and will display a date 3 months in future.. Great..

However if there is no date in column A, then column B displays a default 1900 date.. Is there a way of making this blank if there is no date in col A?

Thanks in advance.....