If the date scale takes up too much horizontal space (is stretched out too much), use of the Force to One Page and Pages Across/Down features in the Print form can also cause the vertical dimension of the spreadsheet to be reduced too much. Although this may seem like an obscure thing to do, to get rid of the blank lines at the bottom of the page, reduce the width of the spreadsheet area or the width of the task bar area.
If you are not using the Force to One Page or Pages Across/Down feature in the Print form, consider adding some lines of text to the header and/or footer for the page (via File, Page Setup), and/or increase their font size (via Format Global Options, Print Header). This would have the effect of decreasing the vertical dimension available to the bordered area, thereby reducing the number of blank lines required to fill up any leftover vertical space. Also consider increasing the top and/or the bottom margin, to reduce the amount of vertical space available for printing.