When a freeze is predicted and you need to quickly protect tender container plants, try this method.
1. Grab a tomato cage from storage and invert it over your container as shown, so the ends stick up in the air. (Placing a small cafe table or an outdoor chair ― right side up ― over the plant would also work.)
2. In the evening, drape thick plastic, burlap, or other fabric over the cage, making sure it doesn't touch the plant's foliage.
3. The next morning, after temperatures have begun to rise, remove the cover and the cage.