Let's face it. Floridians are no experts when it comes to handling cold temps. We are even less prepared on how to protect our landscapes from cold temps. It just doesn't happen very often. With the exception of some north Florida counties maybe. So let's talk about it.

It has been a much colder winter than we had last year. And we are getting a lot of questions on social media about how to tell if plants are being stressed from cold temperatures or by something else. So lets talk about it and down at the bottom, you will find a video I made showing you examples. I also spend a few minutes talking about the basics of microclimates and how they protect my plants from cold weather.

How Cold Affects Plants

Plants are sensitive to temperature fluctuations. Cold weather can impact plants in several ways:

• Cellular Damage: Water within plant cells can freeze when temperatures drop below the plant’s freezing tolerance. Ice crystals form in the cells, causing them to rupture. This damages the plant's structure and impairs its ability to function properly.

• Reduced Metabolic Activity: Cold temperatures slow down the plant's metabolic processes, including photosynthesis and respiration. This can stress the plant and make it less able to take up water and nutrients.

• Disruption of Water Transport: Frozen soil can limit a plant’s access to water, while cold air can reduce the plant's ability to transpire (release water vapor). This combined stress can lead to dehydration.

• Delayed Growth: Cold temperatures can prevent plants from growing or maturing, which affects flowering and fruiting. This is especially detrimental for crops and ornamental plants.

Types of Cold Damage

There are several types of cold damage that plants may experience:

• Frost Damage: Occurs when a plant is exposed to temperatures below freezing, causing water inside the plant cells to freeze. This typically affects above-ground parts, like leaves, flowers, and stems, resulting in wilting, browning, or blackening of the plant tissue.

• Freeze Injury: A more severe form of frost damage, freeze injury can occur when the entire plant or parts of it, like roots or stems, freeze solid. This typically happens when the temperature drops rapidly or remains below freezing for an extended period.

• Chilling Injury: This occurs when a plant is exposed to temperatures above freezing but still below the plant’s minimum temperature tolerance. Chilling injury is often subtler than frost damage, causing slow growth, leaf drop, or overall plant stress without immediately visible signs.

Signs of Cold Damage

The symptoms of cold damage can vary depending on the plant species and the extent of the exposure. Common signs include:

• Blackened or Waterlogged Tissue: After frost or freeze exposure, plant tissues may appear blackened, mushy, or translucent.

• Wilting or Curling Leaves: Cold-damaged leaves may wilt or curl, even in cooler temperatures.

• Browning of Leaf Edges: A common symptom of frost injury, where the edges of leaves become brown or necrotic.

• Branch Dieback: When stems or branches freeze, they may die back, causing the plant to look sparse or have broken branches.

• Delayed Bud Break or Flowering: Cold injury can delay the onset of new growth in the spring, resulting in stunted or missing flowers and fruit.

Preventing Cold Damage

While some cold damage is inevitable in harsh climates, there are several strategies to reduce the risk of damage to your plants:

• Choose Cold-Hardy Plants: Select plants that are suited to your climate zone and capable of withstanding local winter temperatures.

• Proper Mulching: Mulch around the base of plants to insulate the soil and protect root systems from freezing temperatures.

• Protecting Plants from Frost: Use row covers, blankets, or frost cloths to shield plants from frost during cold nights. Additionally, watering plants before a cold snap can help retain heat in the soil and reduce the chance of freezing.

• Provide Windbreaks: Cold winds can exacerbate freezing temperatures. Planting windbreaks or using physical barriers can help shield sensitive plants from damaging winds.

• Bring Pots Indoors: For potted plants, moving them inside or to a sheltered location during extreme cold spells can prevent damage.

Dealing with Cold-Damaged Plants

If your plants have been affected by cold damage, the first step is to assess the extent of the injury. Here’s how to handle it:

• Pruning: Cut away damaged or dead tissue, especially if it’s blackened or mushy, to help the plant focus energy on healthy growth.

• Watering and Fertilizing: After a cold event, ensure that plants are well-watered (without over-watering) and avoid fertilizing too soon, as it may encourage weak, vulnerable growth.

• Patience: In some cases, plants can recover from cold damage over time. Allow them to rest during the cold season, and new growth may emerge in the spring.