Yes, it freezes in Phoenix. On clear, calm nights from December through February, lows dip to freezing, especially in low, open spots. Protect frost-tender plants like bougainvillea, lantana, yellow bells, young citrus, and hibiscus: water deeply the day before, drape breathable frost cloth to the ground before sunset, uncover in the morning, and do not prune damage until mid-February or March.
Which plants are frost-tender
The first step is knowing what actually needs protecting. Plenty of our desert plants shrug off our winters just fine, while others get nipped by even a light frost. Here's the lay of the land:
- Frost-tender (protect these). Bougainvillea, lantana, yellow bells (tecoma), young citrus, hibiscus, natal plum, many potted tropicals, and tender succulents are the usual victims of a Phoenix frost. Young and newly planted versions of even hardy plants are more vulnerable too.
- Usually frost-hardy here. Established palo verde, mesquite, Texas sage, desert spoon, most agave, prickly pear, ocotillo, and our tough natives handle typical low-desert winters without help.
- It depends on the night. A light frost (right around 32 degrees for a short time) does far less damage than a hard freeze (mid-20s for several hours). Watch the forecast lows and how long they'll last.
Microclimate matters a lot. Plants under a patio, against a warm south wall, or beneath a tree canopy stay several degrees warmer than those out in the open or in a low, cold pocket where cold air settles.
Watch the forecast and know your yard
Frost protection is all about being ready before the cold arrives. Keep an eye on the forecast from late fall on, and pay attention when you see a clear, calm, dry night with lows near or below freezing. Those still, cloudless nights are when frost forms. Windy or cloudy nights usually stay warmer.
Walk your yard and note the cold spots (low areas and open, exposed beds) versus the warm spots (near the house, under eaves, beneath canopy). Keep your frost cloth and supplies handy so you're not scrambling at 9 p.m. when a freeze warning pops up.
Water before a freeze
Here's a tip that surprises folks: water your plants the day before a freeze. It seems backwards, but it works for a couple of reasons:
- Moist soil holds heat. Damp soil absorbs more warmth during the day and releases it slowly overnight, keeping the root zone and the air just above it a bit warmer than bone-dry soil would.
- Hydrated plants resist cold better. A well-watered plant is less stressed and more resilient than a thirsty one going into a cold night.
- Water in the day, not at night. Give that deep drink during the daytime so the soil can soak it up and warm before evening. Don't leave foliage wet going into the freeze.
This simple step, done the afternoon before a cold night, can make a real difference for borderline-tender plants.
How to use frost cloth the right way
Frost cloth (also called frost blanket or row cover) is your main tool. It traps heat radiating up from the ground and lifts the temperature underneath by several degrees, often enough to carry a tender plant through a frosty night. Use it well:
- Cover before sunset. Drape the cloth in the late afternoon or early evening while there's still ground heat to trap. Covering after it's already cold misses the point.
- Drape to the ground. Bring the cloth all the way down to the soil and secure it with rocks, stakes, or pins. The magic is trapping ground heat, so don't leave the bottom open.
- Use breathable frost cloth, not plastic directly on leaves. Plastic touching foliage actually transfers cold and can cause more damage. If you only have plastic, keep it off the leaves with a frame, and remove it first thing in the morning.
- Uncover in the morning. Once temperatures climb back above freezing, pull the covers off so plants get light and air and don't overheat under the cloth on a sunny day.
- Old sheets and towels work in a pinch. For a one-off cold night, a bedsheet or light blanket draped to the ground does much the same job. Just remember to remove it in the morning.
For potted tender plants, the easiest protection is to move them. Tuck pots under a covered patio, against the house, or into the garage for the night, then bring them back out once it warms.
Do not prune frost damage too early
This is the rule I most want to drive home, because almost everyone breaks it. When frost browns your bougainvillea or yellow bells, every instinct says to cut off the ugly damage right away. Don't. Here's why:
- The damaged growth protects the plant. That brown, frost-bitten foliage insulates the living wood underneath from the next freeze. Cut it off and you expose tender tissue to further cold damage all winter long.
- You can't tell yet what's dead. Frost damage usually looks worse than it is. New spring growth will reveal exactly where the living wood begins, so you cut in the right place instead of guessing.
- Wait until frost danger has passed. In the low desert that's typically mid-February into March. Once you see fresh growth and nights are reliably warm, cut back to just above the new buds, and the plant rebounds fast.
Patience through winter is the whole game. Ugly is not the same as dead, and an early haircut does more harm than the frost itself.
Planning your winter landscape? Choosing tough, cold-hardy natives means a lot less frost fuss every year. Browse our Native and Desert-Adapted Trees and our Low Water (Drought-Proof) plants that handle our winters with ease, or add a little protected winter color from our Flowering and Accent Trees. We deliver and can install for you.
🌵 Pro Tip: The afternoon before a freeze, do two things: give your tender plants a deep daytime watering so the moist soil holds heat overnight, and have your frost cloth ready to drape to the ground before sunset. Those two simple moves, done early instead of in a panic after dark, carry most borderline plants safely through a Phoenix cold snap.
Frequently Asked Questions
Does it really frost in Phoenix?
Yes. Our low-desert winters are mild, but on clear, calm nights from roughly December through February, temperatures dip to freezing and frost forms, especially in low, open spots where cold air settles. It's usually a few cold snaps rather than a long freeze, but they're enough to damage frost-tender plants if you're not ready.
Which plants need frost protection here?
The usual frost-tender plants are bougainvillea, lantana, yellow bells, young citrus, hibiscus, and tender succulents and tropicals. Newly planted versions of even hardy plants are more vulnerable too. Established natives like palo verde, mesquite, Texas sage, agave, and prickly pear typically handle our winters without help. Watch the forecast lows and how long they'll last.
Why water before a freeze?
Because moist soil holds and releases heat overnight, keeping the root zone and the air just above it warmer than dry soil would. A well-hydrated plant also resists cold better than a thirsty one. Water deeply during the daytime the day before a cold night so the soil can soak it up and warm before evening, and avoid leaving foliage wet going into the freeze.
How do I use frost cloth properly?
Cover plants before sunset while there's still ground heat to trap, and drape the cloth all the way to the soil, securing the edges so warmth doesn't escape. Use breathable frost cloth rather than plastic directly on leaves, since plastic touching foliage can worsen damage. Uncover in the morning once it's above freezing so plants get light and air.
Should I cut off frost-damaged growth right away?
No. Leave the damaged growth in place through winter because it insulates the living wood from the next freeze, and you can't yet tell what's truly dead. Wait until frost danger has passed, typically mid-February into March, then cut back to just above the fresh new growth. Pruning too early exposes tender tissue and does more harm than the frost.
A little preparation and a lot of patience through winter, and your tender plants will sail right into spring.
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