Validation Lists And Drop Down Arrows

From the Excel Toolbar - Data/Validation - I'm successfully using a validation list [drop down arrow] to be able to choose from a list and have whatever value I choose entered into the cell. So far so good. Everything working fine.

Here's the thing though, the list I'm referencing is a column with 50 rows. Sometimes there are many items in the column - up to 50, and sometimes only 3 items depending on other variables in the spreadsheet.

Because the list is referencing the entire 50 rows in the column (only way I know how to do it), during times when the column has only 3 items (3 rows), the drop down still shows a bunch of blank spaces (like 47 of them - tons of white space with a scroll bar window that runs down beyond where one can see), which is awkward (strange looking).

How do I program the validation list to only show as many cells within a range that have actual values within the cell, or where <> "" ? Or, in other words, to leave all blank spaces found in the list = NOT SHOWN.