The National Weather Service has issued a freeze watch for Saturday morning which includes the northeast plains and parts of western Weld County and eastern Adams and Arapahoe counties. It will be possible for some areas to drop down into the upper 20s by sunrise.
This cold would put an end to garden season as many of the uncovered plants in those areas will freeze. Sensitive flowers and porch-side plants need to be covered or brought inside, but it is not yet necessary to shut down sprinklers on the Front Range. It takes an extended deep freeze to damage pipes several inches underground. But if you do choose to leave them on, you will have to cover the backflow preventer which is the part that sticks up out of the ground.