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 hard 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/

Christmas Gifts

 Cool and rainy here (at last) after more than three months of drought.  Many of us have received at least four inches so far.  Lake Jackson has drained again.  Life in the Florida panhandle.  Hoping your Holiday season is filled with love and laughter (and lots of fresh vegetables). 

Water Management during Drought Periods

This swale collects water from the
adjoining permiable driveway through a side
drain when it rains keeping it from flowing
into the street and a nearby lake, and allows
it to sink into the soil for long term storage.  

We’ve been experiencing a prolonged drought in north Florida for the past several months, and no end in sight. Watering gardens, lawns and landscapes regularly is expensive and environmentally unsound. So how do we manage water on our property and in our gardens?

In our hilly area, an effective way to store water is to slow it down and sink it into the soil to be accessed when rainfall is not adequate   Slowing it down involves creating shallow swales or low barriers to stop rainfall or irrigation runoff and allow the water to be absorbed.  A swale across the contour of the property will slow down water, prevent erosion, and accumulate organic matter, which will help the water sink into the soil. A log, a low wall or some other elevated landscape feature will operate in the same way. 

The key to water absorption is organic matter. Even without altering the landscape, increasing organic matter in your soil will increase its water holding capacity.  According to the USDA Natural Resources Conservation Service, a 1% increase in soil organic matter will help soils hold up to 20,000 gallons more water per acre.  This sounds easy, but it will take significant amounts of organic matter for a 1% increase.  

Pine straw mulch in garden beds
and free shredded wood mulch 
around the beds   

Good landscape practices to build soil will accomplish this over a period of time. A significant first step, and something that can be done immediately to help alleviate the drought, is the application of mulch to all exposed soil. This will not only add organic matter as it decomposes, but will reduce evaporation, allowing moisture to remain in the soil to nourish plants.  

Water deeply before laying mulch.   Add an optional layer of cardboard to help retain moisture and suppress weeds, and water again.  Lay mulch three to six inches deep and water deeply again for a good start in moisture retention.

Other beneficial landscape practices:

• Leave the leaves when they fall, either in place or as mulch in adjoining beds. 
• Leave grass clippings on the soil. This will reduce the need for fertilizer and build organic matter in your lawn. 
• Leave plant residue from annuals and perennials on the soil.  Cover it with mulch and let it decompose. 
• Don’t disturb the soil; tilling reduces the soil’s water retention capacity.
• Utilize free wood chips, leaves, and pine straw to cover the soil wherever possible. 
• Where appropriate, grow cover crops, chop them before they make seeds and allow them to decompose. 
• An emerging practice is the addition of biochar to the soil.  Its porous texture helps with water storage and provides habitat for beneficial microorganisms.

All of these practices have multiple benefits, not just for storing water, but for stopping erosion, reducing evaporation, discouraging weeds, regulating soil temperature, providing habitat for beneficial insects and organisms, increasing fertility, and keeping your plants happy.

More info:  https://edis.ifas.ufl.edu/publication/SS661

https://permacultureapprentice.com/permaculture-water-management/

Citrus Ripening Season

 

This grapefruit was still very 
firm and quite tart.  Picked to test
flavor. Fruit on this tree will continue
to sweeten and the pith will narrow. It
should be at peak in several
more weeks.  

Citrus fruits are ripening in North Florida. 

Leaving fruit on the tree has some advantages. The fruit will get sweeter the longer it stays on the tree up to a certain point, and then it begins to get pithy or dry out with loss of flavor. Once the fruit is picked it does not ripen or sweeten any further so it’s important to leave it on the tree until it reaches its peak.

How can you tell if the fruit is ready to pick? Color isn’t always the best indicator of ripeness.  The best way to determine readiness is taste.   Eat a sample from time to time. 

Some citrus varieties hold on the tree better than others.  Mandarins such as Satsumas, Clementines, Tangelos, etc., will not last a long time after maturity.  Their skins will become loose, and their juice will begin to dry up. Lemons can pretty much be left on the tree until you’re ready to use them, and grapefruits become sweeter the longer you leave them.

The bottom line – taste is the key.

Most citrus needs to be picked or protected if temperatures are predicted to go below 28°.  Satsumas and kumquats seem to be the most tolerant of cold temperatures while grapefruits, limes, and lemons will need to be picked or protected when freezing temperatures are predicted.

Two types of mandarins—
Clementines on the left, 
Orlando Tangelos, right.  Orlando 
Tangelo is a cross between
Dancy tangerines and Duncan
grapefruit.  Sweet, juicy, and 
quite cold tolerant. 

A heavy crop of Clementines. 
It has taken a number of years
for this tree to produce tasty fruit.
Clementines are small, a cross
between a mandarin and sweet orange.
These are larger than those you
see in grocery stores because they
were probably pollinated by a
nearby orange tree. They also have
a few seeds for the same reason.   

 Meyer Lemons.  Large and 
sweeter than regular lemons.  

Red Grapefruit - ‘Flame’.  Heavy
bearer of seedless fruit which is
consistently sweet and juicy.  

Cara Cara Red Navel 
Orange.  Developed from a natural
mutation discovered in Venezuela in
1976, the fruit is seedless and delicious
with a unique flavor and exceptional
vitamin content.  They ripen later.

Limequats.  A cross of Key Lime and
Marumi Kumquat.  Small and round,
with tart flesh and sweet rind.  More tolerant
of cold than standard limes.  They can be used when
green or when they become
sweeter as they ripen and change to yellow or
orange.  Unlike other citrus, limequats will continue
to ripen and change color after picking.
They do not have a long storage life 
but last longer when refrigerated.   

Several good references with more information  

https://deepgreenpermaculture.com/2025/03/15/how-to-tell-when-citrus-fruits-are-ripe-a-practical-guide/?amp=1

https://everglades.farm/blogs/news/cara-cara-oranges-origins-unique-qualities-and-uses?gad_source=1&gad_campaignid=21783016276&gclid=Cj0KCQiAiKzIBhCOARIsAKpKLAPepC7qxCBAFRe2rhVK4xlpoolz72jp8NOWvqy8J4CXTADrIU7ewikaAp0CEALw_wcB

https://blogs.ifas.ufl.edu/okaloosaco/2021/12/20/let-citrus-ripen-on-the-tree/

Wednesday in the Garden

 Seen around the VegHeadz garden over the last couple of weeks as we clear up summer’s excess and make preparations for an abundant fall and winter growing season.  

Army worm larvae are still 
active.  As weather cools, the
moths migrate south to
avoid freezing temperatures

The cooler temperatures have also put
native bees into sleep mode.

A general cleanup has freshened up our
entrance arbor. In spring, it is covered
with Peggy Martin roses – also known
as the Katrina Rose.
Photo—Evelyn Gonzalez

Planting is still underway. Nancy G.
is planting many varieties in the root
crop rotation beds—kohlrabi, parsnips,
rutabagas, carrots, radishes, beets,
purple and green sage, garlic, and onions.  
Most of these will not mature until spring.

A banana flower contains an edible core.
The individual flowers are also
reported to be edible. We tasted one.
Very bitter. Preparation of many foods
to make them palatable is important.
Photo—Evelyn Gonzalez

The pollinator beds maintained by
Laurie J. are of prime importance
in managing insects pests in the
VegHeadz garden.

Louie D. And Linda L.
compare notes on current
crops.  

Some rearranging was completed
for the micro irrigation in the
Biochar trial beds. The irrigation cart
was built by Michael D. to manage
all the fittings and parts required.
It can be rolled right to the site
where we are working.
Photo—Lisa Jacobson

Gardeners planted collard starts
and daikon radish seeds
in the biochar trial beds.
Photo—Lisa Jacobson 

Centipedes vs. Millipedes

 

Flat-backed millipede in the family
Paradoxosomatinae

The sound of an “oh no!“ as my neighbor was looking at the new compost in my garden bed made me turn around. She had found a host of little long multi-legged varmints crawling around the edge of the compost within the bed.  She viewed them as pests that I needed to dispose of.  I wasn’t sure.

First identify.  When submitted to iNaturalist, a variety of opinions resulted about what exactly these were. There was agreement that they were arthropods known as millipedes in the family Paradoxosomatinae, but no specific identification was made. 

Scientists have grouped centipedes and millipedes together for identification because of their many segmented bodies. There are more than 3,000 known centipedes and an estimated 8,000 species. There are upwards of 7,000 known and 80,000 estimated species of millipedes.  The inability to make a specific identification is understandable.

Centipedes and millipedes are quite different in their effect on a garden. Both are beneficial, but in different ways. They are not something you want to destroy.

In addition to their long segmented bodies, they are alike in a number of ways: 

• Both have poor or non-existent vision and rely on other senses, like the feel of vibrations.
• The longest species of each measures about six inches in length.
• Both prefer dark, moist environments such as under stones, leaf litter, logs, bark, or soil crevices.
• Both are primarily nocturnal, emerging from their hiding places at night to hunt and feed.  
• Both are beneficial in the garden environment.  

Despite their similarities, their differences are more notable.  The easiest way to identify whether you’re seeing a centipede or a millipede is the number of legs on each body segment. Centipedes have one pair per body segment while millipedes have two. The difference in benefits they provide to the garden are also clear. Centipedes are predators and help to reduce the insect population, while millipedes are decomposers and eat decaying plants and other organic matter, rarely attacking live plants.  

Feature	Centipede	Millipede
Legs	One pair per body segment, legs stick out from the sides	Two pairs per body segment, located underneath the body
Body Shape	Flattened	Rounded
Antennae	Long and whip-like	Short and elbowed
Movement	Fast	Slow
Diet	Carnivorous; preys on insects and other small arthropods	Detritivores; eats decaying plants and other organic matter
Defense	Venomous bite (not usually dangerous to humans)	Curl into a ball and may secrete irritating fluid
Lifespan	1-6 years	2-10+ years

This is once again a reminder to identify what you’re seeing before you destroy something that may be beneficial to your garden.

More info:  

https://carnegiemnh.org/centipede-or-millipede-whats-the-difference/

https://edis.ifas.ufl.edu/publication/IG093

https://content.ces.ncsu.edu/garden-millipede

More About Emerging Roselle Diseases and Pests

Roselle—TYLCV Positive and Anthracnose

In late September, we posted a warning about a new pest found on the Roselle in the VegHeadz garden. Extension agent Mark Tancig subsequently delivered specimens to the UF Plant Disease Diagnostic Clinic for analysis. The analysis report can be seen below. It is not good news. The Roselle is infected by a virus, by a fungus, and two insect pests. The most worrisome part of this report is that these pests and diseases can affect other plants such as cotton, okra, tomatoes, beans, and others.  

Any plants suspected of being infected, either Roselle or any of the other species listed in the report, should be pulled and disposed of in the manner recommended by the lab.

The infestations are not happening just in our garden – the distorted and damaged Roselle leaves have been sighted in other areas of the city as well as in adjoining counties and other areas of Florida.  Additional information can be obtained from the Extension here in Leon County or in your area. This is potentially devastating to home gardeners, market gardeners, and farmers who produce any of the affected species. 

Plant Disease Diagnostic Clinic 155 Research Road Quincy, FL 32351 Phone: 850-875-7140Fax: 352-846-6617  Email: fbiriarte@ufl.edu

PLANT SPECIMEN DIAGNOSTIC REPORT       Specimen # 2025-190

SUBMITTED BY Mark Tancig Leon County Extension Office 615 Paul Russell Rd Tallahassee, FL  32303 tancig00@ufl.edu		PLANT Hibiscus (Hibiscus sp.)		METHOD SUBMITTED Walk-In
		VARIETY Roselle		CLASS Woody Ornamental
		INTERNAL LAB NO.	LAB FEE $40.00	REPLY FROM LAB September 29, 2025
PHONE 850-606-5217	COUNTY LEON, FL	PLANT MATERIAL Leaves		RECEIVED BY LAB September 24, 2025
CONDITION UPON ARRIVAL Good sample, fair information		DIAGNOSTICIAN(s) Fanny Iriarte, Ph.D.
GENERAL OBSERVATIONS Gnarled, deformed leaves. Mottle or mosaic.		DIAGNOSTIC TECHNIQUE(S)     __ Agdia Immunostrip  X  Microscopic __ Reverse transcription-PCR     __ Fatty Acid Analysis  X  Molecular Analysis __ Serological     __ Incubation __ Other __ Techniques     __ Isothermal amplification  X  PCR __ Visual Observation     __ Lab Tests and Services __ Recombinase polymerase amplification      X  Media __ Reverse transcription real time PCR RT-qPCR
GROWER INFORMATION Mark Tancig Leon County Extension Office 615 Paul Russell Rd Tallahassee, FL  32303 850-606-5217 tancig00@ufl.edu		REFERRAL INFORMATION

Diagnosis/Recommendations 

Diagnosis:	Tomato Yellow Leaf Curl Virus (TYLCV) (Begomovirus)
Category:	Virus
Comments:	Your Hibiscus plant tested POSITIVE for Tomato yellow leaf curl virus (TYLCV). TYLCV is one of the most important viral diseases of tomato. TYLCV has been reported to have a diverse host range including 49 plant species belonging to 16 families around the world. In the U.S. it is known to infect plants in the solanaceous family, common bean (Phaseolus vulgaris), and Ornamentals (including Petunia, Lisianthus, hibiscus, poinsettia and others). For more information see: Tomato Yellow Leaf Curl Virus | NC State Extension Publications MANAGEMENT As you know there is no control for viral diseases and the best thing you can do is remove and discard infected plant material away from the site to avoid the spread. It is also important to control the whiteflies to stop the spread of the virus to other host plants nearby. Most of the recommendations for management of whiteflies are related to tomato crop but some information may be useful and applicable to a poinsettia garden in the link below. ENY-478/IN871: Recommendations for Management of Whiteflies, Whitefly-Transmitted Viruses, and Insecticide Resistance for Production of Cucurbit Crops in Florida You may also want to contact Dr. Martini (cc here) for simple methods to control whiteflies in garden setting.
Diagnosis:	Anthracnose (Colletotrichum gloeosporioides)
Category:	Fungus
Comments:	Colletotrichum gleosporioides abundant spores were also recovered from leaf and stem reddish spots. The disease is called Anthracnose. For more information about Anthracnose please see: Anthracnose Disease of Ornamental Plants: A Pictorial MANAGEMENT Remove and discard infected plant material away from the site. Avoid or reduce overhead irrigation, water early in the morning and avoid stress to the plant. Avoid overwatering. Avoid any stress to the plant. Early spring protectant fungicide may help prevent further infections. For possible chemical control recommendations see "Anthracnose" at: 2017 Southeastern US Pest Control Guide for Nursery Crops and Landscape Plantings.
Diagnosis:	Two-spot cotton leafhopper (Amrasca biguttula) (syn. Cotton Jassid)
Category:	Insect
Comments:	Severe damage caused by two-spotted cotton leafhopper (Amrasca biguttula) also known as "Jassid" was also confirmed by our entomologist Dr. Isaac Esquivel. This insect pest, first found late 2024, can cause severe damage on cotton in Florida. It can also attack okra, eggplant, tomato, hibiscus and others. For more information on this pest please see:  Two-Spot Cotton Leafhopper: A New Pest Threat in Florida Vegetables - UF/IFAS Extension Alachua CountyAlso see: PEST ALERT: Two-spot cotton leafhopper For any questions or concern about management of this insect pest, please contact Dr. Esquivel. Please be advised that records produced as a result of this analysis are public records subject to disclosure under Florida law. Plant Disease Diagnostician: Fanny Iriarte, Ph.D. Our lab website: http://nfrec.ifas.ufl.edu/ AND https://plantpath.ifas.ufl.edu/u-scout/index.html

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Wednesday in the Garden — Bamboo, Bananas and Biochar

Linda L. is loading garden mix 
from a pile near one of the 
two bamboo clumps.

Fall planting season is in full swing and our gardeners are busy getting seeds and seedlings in the ground. 

We wanted to give you an update on our clumping bamboo planted in April 2019, and our biochar trial, which got underway at the garden workday on Wednesday.

This looks like a lot of bamboo, but both clumps of bamboo are well behaved and although tall, do not take up much space on the ground.

Clumping bamboos usually develop new shoots in the fall.   A little over a month ago, Louie D. noticed some coming up around the edges of the clumps. She knocked them over and removed them (this is easy before they harden). This left those coming up in the middle. The spiky new shoots can be seen at the top of the clump.  The shoots emerge from the rhizomes at their mature diameter and grow to their full height very quickly, often in a matter of weeks.

The new culms (the bamboo version of a trunk) have grown larger in circumference each year. We like to use them to define paths in the forest garden, and to build garden structures, such as trellises and tomato supports.

The footprint of the clump
is not very large

The bamboo stays erect, except when it rains.  Then the weight of the water on the leaves causes the culms to arch over, sometimes reaching the ground.  They usually return to an upright position after they dry.  If they don’t, we cut them off so they don’t get in the way. The area under the clumps is shady, quiet, and cool. We’re thinking of putting a bench there so we have another place to hang out in the heat.

Clumping bamboos usually belong to the Bambusa genus.  Those in the VegHeadz garden are Bambusa textilis gracilis and  Bambusa chungii barbelatta

Something else we noticed this week is the bananas. After a cold winter and a week of snow on the ground, the bananas got a slow start this spring.   They just recently sprouted a number of huge clumps of bananas. There’s little chance they will mature before cold weather later this fall, but we’ve learned that even when they’re not fully developed, they can be harvested and ripened.  To learn more about our ripening experiment, insert “banana ripening” in the search box in the right sidebar. 

 

When fully developed, this would 
be a substantial
crop of bananas

Banana blooms are complex and
interesting

There is a new row of florets under each bract layer of the red blossom or “heart.” Each row of florets develops into a “hand“ of bananas. Cutting The blossom off will stop new bananas from forming, and direct the plant’s energy into maturing the ones that have already emerged.  The florettes are edible, and the blossom contains an edible core in the center. These are used in Asian recipes.

Learn about bananas from a young expert.  https://www.facebook.com/reel/863820269644395?fs=e&fs=e

Finally, we are preparing to move our biochar trial into the garden.  Four different versions of a compost/biochar mixture have been “marinating” and have now been added to the trial plots.  

Last week—an overgrown
 watermelon patch—and weeds

Watermelons and weeds gone
Four 4 x 4 beds

Six inches of soil removed from 
beds and mixed together to
provide a uniform growing medium
Photo:  Lisa Jacobson

Four different mixtures of 
compost and biochar were 
added to the beds along 
with the mixed soil from the beds. 
Photo:  Lisa Jacobson

The workers who made it happen

Ready for the next phase.   In a 
couple of weeks we’ll plant the
same crops in each bed.
Photo:  Lisa Jacobson