What is frost?
Frost is a thin layer of ice that forms on the surface of your grass and plants when temperatures lower. The water vapor in the air condenses and attaches to your plants, forming a white, frosty-looking sheen on the surface. This frost can reach into some of the plant cells, causing damage and wilting.
Photo Credit: Unique Companies
When does frost form?
Frost forms when temperatures are around 32 degrees F. Sometimes, the temperature does not have to be exactly or below freezing for frost to occur. Frost can start to form at temperatures as high as 42. Frost is more likely to occur at night when the sky is clear of clouds and wind speeds are low or completely still. If it is sunny during the day and becomes overcast in the late afternoon, the clouds create a stronger greenhouse effect, helping prevent frost formation. Winds will also prevent frost crystals from settling on plants.
What does frost damage look like?
Frost damage can look different depending on the plants or grass it is affecting. On grasses such as St. Augustine, frost can fry your grass, turning it more crispy and brown depending on the severity of the cold. Some plants are more tolerant of the cold than others, but for more cold sensitive plants, frost can really put a dent in them. Frost damage can manifest in many different ways on plants. Some plants, such as delicate annuals, will start to droop as temperatures descend past 40, giving them a wilted look. They may perk up as temperatures get warmer during the day. If the wilting is too severe, it can lead to permanent damage, which will cause the leaves to brown and may lead to total plant death. As frost starts to occur, the tips of the plants (i.e. the leaves) will experience the brunt of the damage, as frost will settle there first. The leaves will turn brown upon experiencing intense frost, not recovering from their wilting. On more delicate plants that have fleshier branches such as flowers or vegetables, the branches, not just the leaves, will brown with intense frost.
What plants are most affected by the cold in Florida?
Many plants in Florida are affected by colder weather. Palms are some of the more common plants affected by frost. Tropical plants such as hibiscus, crotons, and birds of paradise are also affected. Some annuals and perennials may be affected. Citrus, mango, and avocado trees are susceptible to colder temperatures. The maturity of the plant will also be a major factor in determining its ability to survive the cold. Younger, smaller plants with fleshier bark are more susceptible. Plants that have been established in the ground for a longer time are more likely to survive.
How do I protect my plants and grass from frost damage?
There are several measures you can take to protect your grass and plants from frost damage.
2. Use Winterizer to strengthen your grass for the winter. During the cold months, plant life tends to go dormant in order to preserve and protect itself. Growth rates slow in order to maintain basal life functions, similarly to how some animals may hibernate during the winter. During that dormant phase, plant roots may shrink inadvertently in order to maintain plant health. That’s why it’s important to use Winterizer this time of year. Winterizer has a higher potassium content than most other grass fertilizers, strengthening your grass’ roots and protecting them from further stress. Strong roots also better prepare your grass for the spring, allowing it to vigorously grow with a shorter recovery time from the winter.
3. In the time leading up to the cold weather, water your grass and/or plants while the sun is out. The earlier you water in the day, the better. The moisture in the ground will trap heat, protecting the roots from the cold. Water releases heat as it freezes, making a natural insulator for the plant's roots. Make sure your soil is well draining so that water does not sit on the surface. Check the soil's moisture level before watering. Do NOT water the plant if the soil is already too moist. Water evaporates slower in the winter, so overwatering will make it difficult for plant roots to breathe. Overly soggy water may invite fungus as well.
4. Cover cold sensitive plants with a blanket before sundown. We recommend our N-Sulate Frost Protection Blankets. Alternatively, you can also use quilts, cloth sheets, or other household blankets you may have. Use Anchoring Pins, rocks, or other heavy objects around the house to keep them in place. Try to cover plants completely with minimal gaps between the cloth and the ground to trap as much heat as possible. For palm trees, wrap the fronds in a blanket and tie it shut like a lollipop.
5. Do NOT use plastic to cover the plants. Unlike cloth or our frost protection blankets, plastic is not breathable, meaning it does not circulate air properly and traps unwanted moisture. In combination with plastic’s poor insulation, this causes the plastic to directly transfer the cold onto points of contact, causing freeze damage to occur faster than if the plastic cover was not even on in the first place.
6. For grass, water the lawn at dawn after nights with near freezing temparatures. The water will help melt the frost that has settled on your grass. Part of what damages the grass is the rapid thawing effect of direct sunlight. The frost on the surface of foliage will act as a magnifying glass, causing the grass to heat up rapidly and frozen plant cells to rupture. Watering the frosted grass before direct sunlight starts hitting it will allow the frost to melt at a gentler pace, preventing further damage to the grass. You can use the same method of watering at dawn on any other plants in your yard that you were unable to cover for the previous night.
7. Bring cold sensitive potted plants inside your home on the night of frost. Depending on the size and number of plants, it may be more convenient to bring them inside rather than covering them. Bringing them inside will protect them from the elements, and one night of being inside won’t hurt them.
What do I do for plants that are already damaged by frost?
Do NOT cut back plants immediately after they have already been damaged by frost. The damaged foliage on the top of the plant will serve to insulate the rest of the plant from further damage. Wait until the spring when temperatures warm up to cut back your plants. That way, your plants are safe to grow new branches without fear of frost.
Winter in Florida can be a difficult time for certain grasses and plants. Preventing frost damage will ensure that the hard work you put into caring for your yard will not be in vain. If you have any questions, feel free to contact us via our email at
info@greenthumbnursery.com or via phone at 813-884-3797. We are more than happy to help!
