Here in the Phoenix area, it doesn't freeze very often, so most of us don't give it much thought. However, because it doesn't freeze often, the plants that most of us have are not very frost tolerant. But that doesn't mean you have to lose all your plants to a single night of frost.
The single most important step in preparing your landscape for an over night freeze - is turning off your sprinkler system! This can be done at the automated timer, or at a valve.
Next, you need to make sure to cover all plants that are frost sensitive. Experts recommend that you do not use plastic. It can trap moisture inside, which will freeze, and it can suffocate your plants. The best option is to use a frost blanket, but in a pinch, using burlap, or even a heavy flannel sheet is better than leaving them uncovered.
Here is a list of plants that need to be covered when there is a frost warning:
- Bougainvillea
- Hibiscus
- Citrus
- Ficus
- Thevetia (Lucky Nut Tree)
- Lantana
- All varieties of Carissa (Natal Plum)
- Tecomaria (Cape Honeysuckle)
- Tecoma (Yellow & Orange Bells)
- Passiflora (Passion Flower)
- Lonicera (Honeysuckle)
- Senecio (Mexican Flame Vine)
- Solanum (Potato Bush/Vine)
- Cuphea (Mexican Heather)
- Nerium (Oleander)
- Petunia
- Geranium
- Lobelia
If your plants do end up with some frost damage; do not prune them until the weather has improved for the year. The layer of damaged material can help to protect the healthy plant from further damage.