Helping Your Food Crops Survive Freezing Temperatures

Our coldest months in north Florida are usually January and February That’s winter for us. During that brief season, we often have at least one killing frost. Our winter vegetables usually survive just fine either as they are, or with a cover.  Cover with frost cloth, a blanket or a fabric drop cloth, not plastic. If you want to use plastic, put a fabric layer between the plants and the plastic,  as they will likely be damaged everywhere they touch the plastic.

Water your plants well when there is a frost forecast.  Water holds and releases heat better than dry soil; moist soil absorbs more solar heat during the day and radiates it slowly at night, keeping roots warmer.  Moist soil also acts like a blanket, slowing down the freezing process and protecting delicate root systems from harsh temperatures and cold, dry winds.  Well-hydrated plants (with cells full of water) are stronger and better equipped to withstand freezing and drying. 

Give plants a deep drink before the freeze.  Water early in the day when temperatures are still above freezing (ideally above 40°F) so plants absorb water before nightfall and temperatures drop.  Focus on watering the soil, not necessarily the leaves, as wet leaves can be more prone to damage.  Don't water if there's already ice forming or the temperature is below 32°F.

Our experience here in two consecutive years illustrates the benefit of watering before a freeze.  The first year we had a freeze during dry conditions, and some of our citrus trees were killed.  Even those that survived lost all their leaves and took a long time to recover. The next year we had rain throughout the day before a hard freeze, nightly temperatures below 32°F  for multiple days, and snow which remained on the ground for a week in some places.  The citrus trees survived beautifully with no leaf drop.  It was quite amazing. The well hydrated soil both before the freeze, and during the melting of snow, obviously made a difference.

Fish and seaweed products have been recommended as soil amendments for years with only anecdotal evidence of their benefits. Recent scientific trials have shown very interesting results for the application of seaweed extracts, including protection of citrus from the ravages of freezing.  It is recommended that extract from a particular seaweed be applied in early fall to citrus trees to increase their cold tolerance.  It may be too late for a beneficial application this year, but adding seaweed extract to the soil in February and following up in August and September of next year should help next winter’s crop. Read the following article from UF North Florida Research and Education Center to learn how this works, what products to use, and the best way to apply them.

https://nwdistrict.ifas.ufl.edu/phag/2025/11/21/boosting-citrus-cold-hardiness-with-seaweed-extract-biostimulants/