Frost damage can occur unexpectedly and, if severe, quickly destroy the flowers and plants in your garden that are susceptible. Unless frost damage is severe enough, and has killed the plant, there are several effective measures you can take to help it recover.
Identifying Frost Damage
Depending on its severity, frost damage can affect several parts of a plant.
Indications of frost damage include:
- Dead fruit and flowers
- Flower buds that become dormant
- Browning and falling leaves, shoots or stems.
All or part of the stem may also turn black. In cases of minor frost damage, only some leaves or parts of the stems or buds may show signs of damage, and even plant parts that appear dead may grow back in time.
Causes of Damage
Some plants may become damaged because they are not "hardy" -- able to withstand the cold below a certain temperature in the area where they're planted. Frosts that occur unexpectedly early or late in the season can also damage plants that would thrive in an area in normal temperatures.
Climates and Locations
Although frost damage is most likely to occur in areas of the country with cold winters, such as Northern states and the Midwest, it can also damage plants in Southern states like Florida. High-elevation areas like parts of Colorado often experience frost even in fall and early summer. In desert areas such as Nevada, frost damage is common because temperatures fluctuate and "frost pockets" of cold air are more likely to occur.
Caring for Frost Damage
Wait and Watch
If you notice symptoms of frost damage in your garden, don't panic. The best response is to wait for the damage to become apparent so you can assess it. On some plants, injured leaves and shoots will show up within a few days, but thicker limbs can take weeks or months to display visible permanent damaged.
Do not prune a frost damaged plant right away. It can cause further damage, or disease or infection.
Rather than pruning immediately, let leaves or bark stay in place until there is no chance of further frost. This insulates and protects the plant and may even help it recover. In addition, new growth may emerge from areas that appeared dead. Once there is no chance of frost, look for new green leaves, or scrape the outer layer of the plant stem to see if the inside is green and alive.
Watering isn't likely to help severely frost damaged plants, but if your garden is suffering from what appears to be mild frost damage, water the area. This can thaw the soil and give your plants moisture they need to recover.
Pruning back dead leaves, stems and shoots caused by frost damage will help your plants' new growth emerge. Wait to prune until warm weather arrives.
Things You'll Need
Bucket or bowl
Fill a medium-sized bowl with 1 part bleach and 3 parts water. Dip a clean cloth in the mixture and thoroughly wipe off all surfaces of your pruning shears to ensure that no disease is present that could damage your plants.
Working from the top of the plant to the bottom with your shears, remove all areas of dead wood and leaves from the plant until only healthy tissue remains.
If most of your plant is frost damaged, prune it back to ground level while leaving any live parts of the stem intact.
Do not fertilize immediately after frost damage occurs. Wait until there is no danger of frost to fertilize.
Fertilizing a frost damaged plant can help it recover more quickly, but only if you wait until there is no more chance of frost. Fertilizing when there is still a chance of frost can cause new growth that will be susceptible to further frost damage.
In spring, apply fertilizer to your garden as usual, or use a dry, balanced, 10-10-10 granular fertilizer sprinkled evenly at a rate of 1/2 tablespoon per square foot of area. After fertilizing, water the garden as usual to help the nutrients reach the plants' roots.
Protect Frost-Heaved Plants
Plants become frost heaved when temperatures fluctuate and the freezing and thawing of the ground causes the soil to expand and contract. This motion can literally "heave" some perennial plants out of the soil and expose vulnerable roots, which can kill or damage the plant. If you notice frost heaving in your garden, gently press the plants back into the ground if possible, or pack a mound of dirt around the exposed parts of the plant to protect it. Cover the area around the plant in 3 or more inches of straw to prevent it from freezing again.
Preventing Frost Damage
Planting frost-tolerant plants, planting in areas with full sun and consistent watering are good ways to protect plants. Planting near walls or benches that absorb heat from the sun during the day will also keep plants warmer when frost occurs. If frost is likely, cover your garden with sheets, blankets or a frost cloth, draping it completely over the plants to trap heat from the soil. Finally, remember that over-protecting plants can be detrimental. If allowed to acclimate to colder weather, some plants will become stronger and handle frost better.
Have frost-damaged houseplants? See How Do I Treat Houseplants That Have Frostbite?