Thinking for the future cold fronts

[byuind]

Living in Northeast FL, i do have to contend with the occasional cold snap. This particular year was brutal as we all know and it really made me think about putting some of my ingenuity to good use.

I am currently in the hypothesis stage, and working to build a plan for the future on how to heat and protect the palms that I have that are cold susceptible. But as much as that is important to me, so is protecting the curb appeal of my home. I want to create a system (or systems) that allow for the further protection of the tree(s) foliage as much as the heart.

 

In a perfect world I could wrap every specimen with xmas lights and burlap and probably do just fine.  In fact I am positive of that as the trees that i was able to do this with are still very green (some burned leaf tips were they were more exposed) but over all look appealing enough form the road. 

 

Where i want to improve is on my larger trees. I am fairly confident that all my large trees are going to make it. I had some concerns about my 30 foot royals but they appear to be coming along. They look utterly terrible though, with their crispy brown leaves. we got down as far as 24 degrees with consistent cold winds out of the north which really tore them up. I have come to the conclusion that it was as much the wind as the cold that did the damage (that is another story all together). Down towards Orlanda they saw lows around 27 with less wind, and the Royals there look much better.

 

Back to my questions: does anyone have any methodology for protecting very large trees from a cold snap? What i do NOT know for sure is if it is the duration of the cold winds, vs the temperature alone that does the severe damage?

 

Looking to learn more and start building a plan.

[Allen]

You are not going to be able to protect fronds on a 30' Royal without massive intervention.  There are ways like you mentioned to protect the trunk and heart.

[byuind]

48 minutes ago, Allen said:

You are not going to be able to protect fronds on a 30' Royal without massive intervention.  There are ways like you mentioned to protect the trunk and heart.

So let’s say for this conversation that I accept this prognosis: major intervention is necessary.

 

what I am more interested im is the damaging effects. I have heard that duration of cold, rather than the actual temperature might have as much, if not more to do with damage of leaves. 
 

for instance a situation where it drops to 25 degrees for 5 hours vs a situation where it is 30 degrees for 48 straight hours

[kinzyjr]

@byuind

A few things that can help:

• Canopy: This is the best thing to mitigate damage from radiational cooling.  Live oak (Quercus virginiana) works great, but in your case, the Royals are already too large to find an oak that could be delivered and serve as a nurse plant.  If used, t also helps to trim your canopy trees around Halloween to let the most sun under the canopy while still maintaining a good protection radius.
• Windbreaks: Several plants serve as great wind breaks.  People use bamboo, hedges, bushes, large bananas, or some combination of plants to protect the north and west sides of their lot.  Cutting the wind speed does halt some of the desiccation you're observing.
• Climbing Plants/Vines: These will help insulate the trunk to protect you from trunk splitting after a freeze and rapid warmup.
• Incorporate Stone/Concrete in the Landscape: A minor effect, but if there is a lot of it that can receive direct sun, the concrete does a great job of storing heat during the day and releasing it at night.  My old stone patio was a concrete pad with pavers pressed into it.  Since I got rid of it, I have more space but my garden does experience a bit more cooling at night.
• Christmas lights (C9): These can provide a small amount of additional heat that helps on still, radiational cooling events.  Make sure you get non-LED.
• Ground cables: Helps keep the ground warm to promote root function for long duration freezes.  Additionally, since the ground is warmer than the air, you do get some of the same benefit as with the Christmas lights.
• Grade change: If possible, elevate your planting slightly or lower the surrounding area in order to get the coldest air to move away from the palm.  This isn't as easy near the coast as it is here in the hills.

None of these will save anyone from a 1980s freeze, but they'll reduce your year-to-year damage. 

In my own case, I use canopy, windbreaks, stone/concrete, and grade change to alter the thermodynamics of my yard with some success. 

[flplantguy]

Mitigating cold damage is my main goal on my new property as well, thanks for the awesome list!

[SeanK]

I recommend planting the front yard 100% cold-hardy. Reserve marginal and delicate plants for the back yard.

[kinzyjr]

10 minutes ago, flplantguy said:

Mitigating cold damage is my main goal on my new property as well, thanks for the awesome list!

You're very welcome.  Welcome to the forum as well!

9 minutes ago, SeanK said:

I recommend planting the front yard 100% cold-hardy. Reserve marginal and delicate plants for the back yard.

.... especially if your property has northern or western exposure in the SE USA.

[byuind]

So my yard definitely has E - NE exposure in the front. And to make things more complicated, the way my development was set up, multiple small neighborhoods were built about 300 yds apart on an open marsh. So essentially they built them up 12 feet above sea level, and unknowingly to me, created a true “wind tunnel” effect. This caused a whole rash of issues during the hurricanes as I learned because the palms one side of my house got absolutely hammered, while the other side did quite fine. 
 

so the side that opens up to the east gets obliterated by wind in some cases. During the cold fronts, this side gets beaten up by the chill winds and for the events that pair up with sub 32 temps, I want to protect.

 

I have some ideas on how to bring heat to the tree overnight that are pretty intuitive (if I can make them work!) but I first strive to understand the effect of the wind on the leaves vs the cold temps themselves 

[kinzyjr]

13 hours ago, byuind said:

So my yard definitely has E - NE exposure in the front. And to make things more complicated, the way my development was set up, multiple small neighborhoods were built about 300 yds apart on an open marsh. So essentially they built them up 12 feet above sea level, and unknowingly to me, created a true “wind tunnel” effect. This caused a whole rash of issues during the hurricanes as I learned because the palms one side of my house got absolutely hammered, while the other side did quite fine. 
 

so the side that opens up to the east gets obliterated by wind in some cases. During the cold fronts, this side gets beaten up by the chill winds and for the events that pair up with sub 32 temps, I want to protect.

 

I have some ideas on how to bring heat to the tree overnight that are pretty intuitive (if I can make them work!) but I first strive to understand the effect of the wind on the leaves vs the cold temps themselves 

I agree with your assessment that the damage was amplified by the wind.  That's certainly the case anytime we get advective cold like this year and 2018.

Advective cold fronts (defined as an event where wind speed is consistently at least 5mph) have distinct characteristics that make them harder to mitigate than radiational cooling. 

One of the big reasons you see more cold damage on 30-foot royals on a windy 24F vs. the same or worse temperature on a still night is because all of the moving air mixes and eliminates the air stratification that happens during our short radiational cooling events.  Official temperature in the USA is measured at 4ft.-6ft.  On a still night in Florida, the temperature at 30 feet can be +5F to +10F over the temperature measured officially.  During an advective event, the air mixes to the point where the temperature is much more uniform.  On a radiational 24F night, the temperature near the crown of your royals might be 30F+.  On an advective night, it's likely within a degree (24F-25F).

A trade-off for the mixed air is that advective cold does not typically allow frost to form.  That's good for palms that are more chill tolerant and less frost tolerant.  Depending on how high the wind speed is, the wind can remove heat from plant tissue faster and dry exposed areas out.  For tropical/subtropical palms, that can spell a lot of foliar damage for those thin, exposed leaflets.  Bud death is also possible, particularly if they have thin trunks without the mass to protect the bud (ex. Veitchia or Ptychosperma).

Advective cold tends to erode or erase microclimates, especially those afforded by UHI or water modification.  As a result, you'll see a lot of unexpected damage going by temperature alone.  There will still be some areas that stay a little milder, but the difference won't be as much as during a radiational freeze.

Unfortunately, advective cold fronts are more difficult to mitigate than radiational cooling.  With radiational cooling in Florida, overhead canopy will stop most or all of the damage.  With advective cold, short of being tight up against a concrete building blocking the wind entirely, you'll see some unexpected damage.

All of this said, if the royals are OK and recovering after ~24F of any sort, they are well-kept.

[SeanK]

Looks like southern California to get hit hard with a winter storm this weekend.