Harry wrote:

Hello



I'd like to know if there is a better way to blow the water out of the line
than just turning off the shut-off, opening up the drain cap (to let the
air in) and turning on the tap in the garden.


Now, to be clear: This drain cap is indoors, between your shutoff and
the garden tap?

I would be tempted to plumb a way to fill this length of tubing (exposed
to the cold) with RV antifreeze. Perhaps with a shutoff followed by a
standpipe, giving you enough height to put the opening taller than the
outdoor tap (so that gravity alone gets the job done).