Sure, sticking your thumb in the open end of a garden hose can work in a pinch, but for the best results (and to save your fingers from cramping), you need a hose nozzle sprayer. Like pruning shears, ...

While we rely on our garden hoses to keep our outdoor spaces looking ... Cut the post to the desired length, and paint and apply a clear coat (like varnish) to protect it from the elements.