People are always surprised that we take freezes seriously in Florida. Anyone who has spent a winter in Jefferson County isn't. We're 8b up here, and we get frost, hard freezes and the occasional cold snap that wrecks a landscape overnight. Your turf will almost certainly survive it. Your camellias, citrus and container plants are what you actually stand to lose, and most of that loss is avoidable if you know which kind of cold is coming.
Three kinds of cold, three responses
Homeowners hear "freeze warning" and treat every event the same. They aren't the same, and the difference decides what actually works.
Light frost
Air temperature at or just below freezing on a clear, calm night. Ice crystals form on plant surfaces and on the grass, because those surfaces radiate heat away to a cloudless sky and get colder than the air around them. Tender annuals and new growth on tropicals get burned. Established plants shrug it off. A sheet over a tender plant handles this easily.
Hard freeze
Temperature drops well below freezing and stays there for hours. Ice forms inside plant tissue, cell walls rupture, and the damage goes past the surface into stems and, in containers, into roots. This is the event that takes out citrus, tender tropicals and anything marginal for our zone. Covering helps, but it has to be done right and it needs help from the ground.
Advective freeze
This is the mean one. Cold air moves in behind a front, temperatures crash, and the wind blows all night. Because the air is churning, the usual tricks stop working. Heat radiating out of the ground gets stripped away instead of pooling under your covers, and the covers blow off or pump cold air underneath. There's no clean fix. Protect what you can, anchor everything hard, move what's movable indoors, and accept some losses.
The turf is usually fine
Your lawn already has a strategy for this. Warm-season grass goes dormant, moves its energy into crowns and stolons at and below the soil line, and lets the top growth die back. Frost on a dormant lawn is a non-event: don't cover it, don't fertilize it, don't try to protect it. The full picture is in our post on winter dormancy. The exception is a thin or stressed St. Augustine lawn, which has the least cold tolerance of the grasses common around here. Even then, the protection happens in fall through proper feeding and mowing, not with a tarp in December.
Water the soil the day before a radiational freeze
Counterintuitive, but it works, and it's the most underused tool people have. On a clear, calm night, moist soil absorbs more heat during the day and radiates it back up around your plants overnight. Dry, fluffy, heavily mulched soil insulates instead, keeping that heat locked underground where it does the foliage no good. So the day before a forecast frost, water the root zones of the plants you care about. Do it in the morning or midday, not at dusk, so the foliage is dry going into the night. This is about warming the soil, not the plant, and it's free.
Don't confuse that with the overhead sprinkling growers use on crops. Coating plants in ice only protects them if the water never stops, and if it does stop, the ice does more damage than the freeze would have. That's a technique for people with commercial systems and a reason to use it. Running your sprinklers during a freeze is a great way to get an ice-covered driveway and a broken irrigation line.
Covering plants the right way
Covers work by trapping heat radiating up out of the ground, which means the cover has to reach the ground to work at all. Most of the covering we see fails on that one detail.
- Cover to the ground, not just over the top. A sheet draped on a shrub like a hat traps nothing. Take it all the way down to the soil on every side and weight the edges with bricks, rocks or soil so warm air can't escape and cold air can't get under.
- Use frost cloth, old sheets, blankets or burlap. Breathable fabric is what you want. Frost cloth is worth buying if you do this every year, because it breathes and can stay on through mild daytime temperatures.
- Never let plastic touch foliage. Plastic conducts cold straight through to whatever it rests on, and you'll find a burned print of it on the leaves in the morning. If plastic is all you have, build a frame with stakes or a tomato cage so it can't contact the plant.
- Take covers off in the morning. Once the sun is up and it's above freezing, uncover. Plastic left on in the sun turns into an oven fast, and even fabric left for days blocks light and holds moisture against the foliage.
- Anchor for wind. If a front is pushing through, whatever you set out will be in your neighbor's yard by 2 a.m. unless it's genuinely secured.
Mulch, containers and the small stuff
Mulch is root insulation and the cheapest freeze protection you can buy. Two to three inches of pine straw or bark over the root zones of tender shrubs and perennials holds soil warmth and buffers the swing. Pull it back off the trunk itself, though, because piling mulch against a stem is a rot and pest invitation in any season.
Containers are the most vulnerable things in your landscape and people forget it. A potted plant has roots exposed to freezing air on every side instead of buried in insulating earth, so it freezes far harder than the same plant in the ground. Move containers into the garage or a shed, or at minimum tuck them tight against the south or east wall of the house under an overhang, grouped together so they buffer each other. If you can't move them, wrap the pot, not just the plant.
Do not prune the damage off
This is the mistake that turns a bad freeze into a dead plant. The morning after, the foliage looks awful and everybody wants to cut it back. Don't. That mushy, browned-out top growth is insulating the living wood underneath, and cutting it away exposes what survived to the next cold night, which is often only a week out. Pruning also stimulates new growth, and tender new growth in January will be killed by the next freeze. Leave it ugly. In spring, once things are reliably warm and you can see where new growth is actually emerging, prune back to living tissue. You'll be surprised how many plants you would have killed in January come back on their own in April. The only thing to cut immediately is a limb that's broken and hazardous.
Stay off the frozen grass
One more, because avoiding it costs nothing. Do not walk, drive or park on frosted turf. The water inside the leaf blades is frozen solid and your weight shatters those cells. The tissue dies, a dormant lawn can't grow out of the injury, and your tracks stay visible until the lawn regrows in spring green-up. Wait for the sun to melt it off, usually about an hour after it hits the grass. Same goes for the dog, the kids and the trash cart.
If you want your landscape looked after through a cold winter instead of triaged after it, we handle that as part of regular maintenance for properties around Monticello. Let us know what you're trying to protect and we'll build the plan before the first front shows up.