With January comes cooler weather along with the possibility of an occasional frost or freeze. But even without, we are sure to have several cold fronts that bring near-freezing temperatures. It’s important to understand that your plants are more likely to be injured by sudden drops in temperature than gradual changes we may see throughout the season. With some planning and preparation, you can save your plants from permanent damage.
Planning for Cooler Temperatures: Before you Plant
One of the benefits of living in beautiful SW Florida is the ability to garden year-round, even in the Winter! However, winter months, and in particular January and February, bring with them the potential for cold snaps that can damage or kill some plants (i.e., Hibiscus, Crotons, Ixoras, Adoninia Palms, etc.) To mitigate the risk, choose plants that are resistant to colder weather, such as Petunias, Violets and Snapdragons. For your food garden, that would include vegetables such as Carrots, Turnips, Kale and Broccoli.
Equally important to choosing the right plants is choosing where to plant. As cold fronts (i.e., wind and precipitation) typically arrive from the west or northwest, the east and southeast sides of your home remain the warmest during cold events. Similarly, plant along natural windbreaks such as buildings, fences and cold hardy hedges. Likewise, avoid “low spots” or other pockets where cooler air settles.
Of course, we live in a subtropical climate and few of us will forgo the beauty of our tropical plants. We love our Crotons, Impatiens, Marigolds, Coleus and ZZ Plants.
Regardless of your plant choices, know your plants and their susceptibility to cold weather.
Preparing for Cooler Temperatures and a Frost/Freeze
Healthy, well-nourished plants can withstand cold temperatures and the occasional frost much better than those that are stressed. Be aware, however, that the well-intended late fall fertilization can produce new growth that’s easily damaged by the cold.
Likewise, pay attention to the local forecast. Most approaching cold fronts are forecasted days ahead, allowing plenty of time to make preparations for a cold weather event. Remember, plants don’t produce their own heat so it’s up to the gardener to protect them from cold.
Move potted or hanging plants indoors or to a garage, breezeway or other protected area. If that’s not possible, group them along a wall which will typically retain heat. For inground plants, additional precautions can be taken (as follows).
Water the soil
Hydrated soil will retain overnight heat and insulate the roots. This should be done the day prior to the freeze or arrival of cold temperatures. Do not, however, wet the leaves. And of course, turn off your sprinkler system.
Cover your plants
When a frost or freeze is forecast, you’ll want to cover your plants. Ideally, a breathable frost cloth provides the most protection and are available in multiple weights. If not available, blankets, comforters or thicker sheets can be used. Coverings should be draped over the plants and touch the ground, using rocks, stakes or other heavy objects to hold them in place. The intent is to trap the heat while allowing the plant to breath. Do not use plastic, as it’s not breathable and can damage leaves should it be in contact with leaves in freezing temperatures. It’s advisable to use some type of framework (i.e., hoops, stakes, etc.) to prevent any covering from resting on the plants, bending branches or compressing leaves.
A cloche is ideal for smaller plants. Similarly and more economical, containers such as buckets, baskets, pots and others can be used. Regardless of what is chosen, plants should be covered well before sunset so that heat can be trapped before the cold weather arrives.
Unless daytime temperatures remain below freezing, remove coverings during the daytime to allow plants to take advantage of sunshine.
Add Mulch
Mulch will retain heat-saving moisture from prior irrigation. Likewise, it will absorb and hold heat from daytime sunlight, insulating the underlying roots. It also lessens the amount soil heat that is lost through nighttime diffusion.
Consideration for Fruit, Citrus and Ornamental Trees
Cold temperatures can damage fruit, citrus and ornamental trees just as it can your garden and landscaping plants. Citrus and avocado trees are especially vulnerable, as are palm and magnolias. Some fruit trees, including mulberry and fig are locally less susceptible to cold.
In general, make sure you have one to two inches of mulch around the base of the tree. This will provide insulation for the roots and retain heat and moisture. Likewise, water your tree prior to the cold snap.
To further protect your tree, you can loosely wrap it (with burlap, frost cloth or other absorbent material) from the base of the trunk upward, thereby blocking cold air while enabling ventilation. Tenting the tree will offer similar protection. Make sure that the covering extends to the ground, as it’s important it holds the heat inside as much as possible.
Plant Recovery
Watering your Plants
After a freeze, watering your plants will help them thaw potentially frozen soil. Likewise, watering will replenish moisture lost to normal transpiration and otherwise unavailable due to being frozen.
Pruning
You can safely snip dead leaves once they turn brown. More vigorous pruning should be avoided until you see new growth; otherwise, you risk over pruning and further damaging the plant. Importantly, these damaged branches can protect the plant from additional cold damage.
Not all damage from the cold weather event will be immediate. Well after the cold weather passes, you may see leaf drop. Foliage burn is common, resulting wilting, tanning, browning or blackening of the leaves. Fungus may also appear for which standard fungal treatment is advised.
Similarly, palms may also be adversely affected by cold weather. You may see darkening fronds and slowly growing, curled new leaves. As these may signal more serious damage to your palm, watch closely over coming weeks and seek professional assistance as needed.
In general, it’s good practice to give your plants time to naturally recover without significant intervention. While new growth may take longer, nature does have a way of healing itself.
Quickly return plants to normal locations
Once the threat of cold weather has passed, move your potted and hanging plants to their original locations. If you haven’t already, remove covers from outdoor plants. Doing so will allow your plants to return to normal growing conditions, eliminate stress and begin to natural repair any unseen damage.
Conclusion
Fortunately, winters are relatively short and freezes are not common in southwestern Florida. Watch your local weather forecast and plan and prepare as needed. Importantly, enjoy Florida’s year-round gardening climate!