JEB66, that only works when cell is empty, no formula, no nothing.
Watco/ Denial, if you don't mind vertical lines happening at either side of the "blanked" portion, you can modify IRstuff's approach and, instead of blanking with "" in the IF statement, insert a large (many orders of magnitude) negative number in the charting column. You need to be charting with straight lines and not "smoothing" to make the points join properly, but you will have near vertical lines at the break.
If you use a large enough number, it will appear as #### in the column anyway.
Advantage over manually deleting zero or blanked cells is that the formula is retained in each of those cells.