How cold is too cold and how do I protect plants from freezing temperatures?
Some plants die back naturally during winter. This firespike (Odontonema strictum) will grow back from its roots. Courtesy: R. McDaniels
The good news; plants selected for site conditions have greater chances of surviving and thriving. Over the past weeks, plants have been preconditioned by exposure to cooling temperatures (Florida Automated Weather Network, FAWN).
Likewise, well hydrated plants survive cold better than water stressed plants. Rainfall or irrigation will benefit inground plants, however containerized plants, or newly installed plants may need extra care prior to the colder temperatures.
Irrigate soil and roots if you don’t receive rain. Well-watered soils absorb more solar radiation compared to dry soil. However avoid prolonged saturated soil conditions as this condition starves roots of needed gas exchange.
Water containerized plants. Move them to a protective structure if frost is expected or from drying winds. Group together to minimize heat loss from the containers.
Covering plants is beneficial during frost, not so much with cold. Drape to the ground, and anchor cloth in place. Soils re-radiate heat during the night. Five gallon buckets and gallon jugs with bottoms removed may be placed over small plants. PVC tunnel hoops, tomato cages, A-frame ladder, and temporary wood structures provide support for cloth. Remove cloth or lift to allow soils to warm during daylight hours.
How does mulch protect in freezing temps?
Properly applied mulch may enhance the landscape.
Mulch helps retain soil moisture. It also creates a buffer between soil and air, protecting roots from cold extremes (Rainey et al, 2022). After watering, add a 1-2 inch layer of organic mulch.
Do not apply mulch to citrus. Do not mulch on top of any newly planted root ball.
Maintain 3-4 inch mulch-free zone around trunks and stems. Types of organic mulch include chopped leaf litter, small or medium hardwood, pine bark nuggets, and pine needles. Melaleuca bark nuggets are available. A thin layer of shredded paper topped with mulch is an economical option.
Decomposing mulch may add texture and nutrients to soil. However, soil under mulch takes longer to warm up in spring.
Shredded cypress mulch is not recommended. Cypress tends to settle and pack down. It forms an impervious layer that sheds water. Periodically rake through mulch to refresh, loosen, and allow water to percolate.
What else may be done?
Good cultural practices will keep your plants healthy. Healthy plants tolerate cold temperatures, drought, insect, and disease pressure better than stressed plants. Healthy plants will recover from cold injury faster than stressed plants.
Routinely inspect for pests.
Fertilize and prune properly (Park Brown, 2021). UF offers guidelines for establishing, pruning and fertilization for plants of all sizes and growing conditions. This is a link to UF’s online database, search for plants of interests. AskIFAS powered by EDIS https://edis.ifas.ufl.edu/
Choose plants suitable for your site. Micro-climate, care during establishment and placing the right plant in the right place come into play. Plants adapted to the climate, pests and disease tend to require less maintenance. This applies to exotic as well as Florida native plants.
Young trees, flowering tree, fruiting trees, and new growth are more vulnerable to cold injury.
Consider micro-climates, pockets of cold or warm areas. Tree canopy, structures and buildings may create micro-climates. Cold air tends to settle in low lying areas. Plant may recover and thrive despite cold damage. If you suspect cold or frost damage, be patient. Best wishes and let me know if you found this post to be helpful. Until next time – Happy Gardening!
CITE:
National Oceanic and Atmospheric Administration, NOAA, Weather Predication Center, https://www.wpc.ncep.noaa.gov/#page=ovw
Don Rainey, Esen Momol, Jennifer Marvin, Tom Wichman, Chris Marble, Lynn Barber, and Susan Haddock, 2022, Florida-Friendly Mulches and Their Uses, https://edis.ifas.ufl.edu/publication/EP626
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