Southern California Coastal & Inland Valleys
Frost Settles Straight Down
Focus attention to protecting the tops of plants and trees from frost damage. Leaving the sides open is okay, especially if air circulation is good, according to University of California Davis research. If you use plastic sheeting, don't let it touch the foliage, or the foliage may freeze more readily because the plastic conducts the cold directly to the leaves.
Protect citrus from cold damage by wrapping the tree trunks in newspaper and covering the foliage with plastic sheeting. Cold soil and dry winds can cause the rinds of ripening fruit to develop bleached blotches, and the leaves to turn yellow where the sun strikes. Provide temporary light shade or plastic sheeting to protect the southwest sides of plants from chilling winds. Be sure it doesn't touch the foliage, as this may increase frost damage.
Move container cacti, succulents, and potted trees under cover for protection from cold and rain. For overnight protection when frost threatens, cover bougainvilleas, fuchsias, hibiscus, and other subtropicals with large cardboard boxes; or drape old sheets or tarps on stakes over them.
Favorite or New Plant
Your Living Christmas Tree
If you plan to decorate a live Christmas tree indoors and then move or plant it outdoors afterwards, choose a relatively small tree, as it will adapt better than a more mature one. After you bring the tree home, water it well and store it in an unheated garage or outbuilding for two or three days as a "half-way spot" until you move it indoors. Keep the rootball moist and the boughs misted.
Once the tree is in place indoors away from heating vents or fireplaces, either water it directly or by scattering ice cubes around the soil surface to slowly seep down into the entire root ball. Limit its time indoors to a maximum of seven days; fewer if the house is very warm.
Move the tree outside again to the garage, shed, or protected spot for at least two weeks before moving or planting it in the open. The longer you enjoy the tree in the warm house, the longer it will need to readapt to outdoor conditions.