When a freeze occurs, the cells within a plant undergo a series of changes that can be quite damaging. As temperatures drop, the water inside the plant cells begins to freeze. This process causes ice crystals to form, which can puncture or rupture the cell walls, leading to cell death. The extent of the damage depends on how quickly the temperature drops, how long it stays below freezing, and the plant’s ability to acclimate.
In regions like San Antonio, where winters can be unpredictable with fluctuating weather, these temperature swings pose a severe threat to plant health. A freezing day followed by a warm spell may coax plants into breaking dormancy, encouraging new growth that is particularly vulnerable to subsequent freezes. When another cold snap hits, this tender new growth is often damaged or killed, weakening the plant overall and sometimes leading to its demise. This is also one of the reasons we advise limiting your pruning around this time of year. Pruning encourages new growth.
Protecting Plants Through A Freeze
It’s crucial to protect your cold-sensitive plants, even those that are typically more cold-hardy, during these times. Damage to the cell structure may not be immediately visible. It often manifests later as wilting, browning, or dieback once the plant resumes active growth and tries to transport nutrients through damaged tissues. This delayed reaction can be misleading, making it seem as though the plant was unaffected by the cold until it’s too late to take action.
To safeguard your plants, consider several protective measures. Covering plants with frost cloths or blankets during cold nights can provide an essential buffer against freezing temperatures. It’s essential that you secure all sides around your plants when covering to protect from icy drafts, and to keep protection in place. For smaller plants, using cloches or overturned pots can create a mini-greenhouse effect, trapping heat and moisture around the plant. Adding a thick layer of mulch around the base of plants helps to insulate the roots and maintain a more stable ground temperature.
Additionally, watering your plants before a freeze can be beneficial because moist soil retains heat better than dry soil, providing extra warmth to the root zone. This is best accomplished a day or two before a freeze is predicted; or at least no later than the morning of, and definitely before the sun goes down. However, avoid watering during freezing periods, as this can lead to ice formation that exacerbates damage. Download our free winter protection guide here.
Ultimately, when it comes to protecting your plants from freeze damage in winter, it’s better to err on the side of caution. Taking proactive steps to shield your garden from the sudden fluctuations of winter weather can save you from the heartbreak of losing beloved plants and ensure that your garden emerges healthier and more vibrant in the spring.
~The Happy Gardener, Lisa Mulroy
