Plant are damaged when cold temps freeze the water in the stem and leaf cells. The cells swell as they freeze then burst.  Holding the air temperature around the plant from dropping to 32F can save them from frost.

The easiest way is by covering.  Covering the plant with a drop cloth or shade cloth will create a static airspace that will stay slightly warmer than the outside air.  The cover can be porous such as floating row cover or shade cloth or solid such as a old bedsheet.  The cover should be held away from the foliage by propping it up with stakes.

Spun row covers on frames protect young crops from harsh weather

A quick fix for larger plants such as citrus or beds of annuals is to drape large, old fashioned holiday lights over and through the plant.  The lights give off enough heat to keep the frost at bay.

Cold air settled in low spots and in confined spaces where the air is still.  Large citrus growers keep frost from damaging crops by using large propeller fans in the orchards.  A patio can be protected to some extent by using am oscillating pedestal fan set up to keep the air moving all night.

Combined with other protection methods, you can protect your plants, at least temporarily from damaging frosts.