Yes, branch and trunk dieback comes from the desiccation of the branches as well as the cold. I keep most of my figs in containers in my detached garage, which is pretty much just a big shed and has no real weatherproofing. I’ve put a min/max thermometer in it and found that gets to almost the same lows as outside (just a degree or 2 higher than outside lows), but I’ve never even had tips die back although not all of the figs I have are known to particularly hardy. While I’m sure it is drafty inside, I think blocking the wind, plus buffering the rate of temperature change makes all the difference.
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There are so many examples of plant winter protection. Often times we see homeowners erect enclosure of burlap to protect evergreen trees or shrubs. There is no insulation, no full enclosure and no active heat source. But the simple and cheap burlap can provide one level of winter protection though this is hard to quantify.
If left unprotected, the sun, rain or snow, and the gusty wind can quickly take out the life from the fig branches.
@zendog –
Honestly, I’m not concerned about whether tips die back a few inches. The fig tree will pop buds from any available node. But you claim that "branch and trunk dieback comes from desiccation of the branches. . . . " Do you have any scientific evidence to support this claim? I’m not aware of any. To the contrary, I know that desiccation is part of the protective process that the fig tree engineers as it goes dormant. Less water means less freezing.
What is the lowest temperature that your trees have endured? I ask because the people I see making this claim about wind generally come from Z7, where a difference of a few degrees (e.g., 0 F vs +5 F) is the difference between extensive damage and none. In this zone, a light, poorly insulating cover might retain enough warmth to make the critical difference. But what happens in Z5 when a grower puts fig trees in an uninsulated shed that admits no wind but lets temperatures drop to -5 F or lower? The fig trees die.
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Like a lot of things in our gardens, fig hardiness isn’t something I’ve seen much real research on, and claims of a variety surviving a specific temperature seem to vary wildly which I’m sure are connected to a lot of variables.
Unfortunately, I don’t know of any specific research with figs, but when the ground is cold and/or frozen and the plants are doing as you say - cycling water away from the above-ground growth to reduce cell damage due to freezing - the addition of evaporation of moisture from buds, stems, etc. from wind can be deadly. Here is an abstract where they look at desiccation levels that kill various types of dormant buds (done for determining preservation not hardiness, but it shows the results): https://www.researchgate.net/publication/282722427_Desiccation_studies_of_dormant_buds_from_selected_woody_horticultural_plant_species
There are also various extension and university information sheets put out that discuss winter desiccation dieback in other species, for instance:
The hardiness of figs is definitely dependent on a lot of factors. I have no experience with Z5 or pushing figs to extremes, but I’m pretty sure I saw 4 degrees in my garage in one of the polar vortex years and my one year rooted cuttings of a red Sicilian fig showed no issues in the spring, while it probably got to 2 degrees outside and the mother tree those cuttings came from in my neighbor’s yard (up against his house) died to the ground. The thickest trunk on his fig was at least 5 inches. All the other figs in the neighborhood and community gardens also had severe if not total dieback that year. I was particularly surprised my young rooted cuttings were alive since people often say container plants are at least a zone or 2 less hardy than those grown in-ground. Sorry, I can only give you the temps by what I remember since I didn’t keep a journal of it, but I think those numbers are correct.
As I said in my post above, I think the slowing down of the heating and cooling cycles in the garage is probably also helpful.
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Probably not entirely fig related. I’ve seen growers water their plants before frosts. It is said that when cells are saturated with more water, it protects the leaf cells from the freezing cold.
Effects of Irrigation and Frost
Water in plant cells acts as an insulator, cushioning the plant cell wall and protecting it from the damaging effects of a freezing night. Water also increases the soil’s ability to retain heat from the sun, insulating the plant’s roots and protecting them from harm, advises the University of Florida IFAS Extension. Because humid air retains heat better than dry air, the evaporating water also provides a layer of protection for the plant’s foliage and blooms.
Citrus growers in FL also spray water before frost. It is said when water turns into ice, the process releases heat to the leaves.
I think this may partially explained the fig die-back from water, cold, wind etc. This may also explain the fact that the small branch I mulched with leaves looks viable than a 1" strong branch exposed to the sun, wind and cold.
Right, I doubt the relevance to figs or even to dormant trees generally. These articles from FL and CA seem to refer to water in growing cells, such as leaves. Like, how do I protect my leafy citrus trees from coming freeze?
I don’t think you have any basis for this claim at the temperatures we’re discussing (i.e., ~0 F). One of your references cites temperatures in Nebraska, which generally reach -15 F more or less. The other tests a protocol that involves chilling tissues gradually to -30 C (-22 F).
Please note that I’m not arguing that wind is irrelevant. I just find it a serious mistake to prioritize wind. By all means, block the wind. But if the temperature is lower than roughly +5 F, expect your fig trees to die anyway. The best protections use the warmth of the ground to raise the temperature within the cover.
So use an insulating cover to retain heat from the ground; consider any reduction of wind a side-benefit.
I can only say that, I’ve learnt that plant or branch that dried from the wind are more susceptible to cold damage, compared to the plants not damaged by the wind. Sure this is marginal and we are not talking about 10F difference.
All those things are small. But figs are considered marginally hardy in our zone 5, 6 and 7. All the small things matter. And all of them add up to the survival of the in-ground trees. Even some members in zone 4/5 has had success with in-ground fig planting.
I treat fig trees just like container trees. Not looking for Holy Grail hardy fig trees that can produce 500+ per tree. If 1/2 of my trees receive winter damages and the other 1/2 of trees can produce 100+ or 200+ figs each, I’m far ahead of the container growers. Over time I can select more productive varieties and improve cultivation techniques. This is the fun of growing fig in ground in our cold climate.
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I watched this guy on YouTube much last year and he can sure talk figs… and has been growing them and protecting them from z7 Temps a long time.
In this video he shows how he protects his.
I cut mine way back… to make it easier to protect them (so far at least losing breba crop)… but he leaves his quite tall… to get that breba crop… and he has some very tall Celeste and Peter’s honey trees that he protects something like 15 ft of growth on.
They are big trees…
He mostly just wraps his with stuff, old quilts, any kind of insulating material he can get… and perhaps a tarp on the outside layer…
But I remember he also includes a low watt bulb inside… and has the proper wiring for that to make it safe… and has wiring inside his house to make it convenient…
On those one or two nights each winter when it gets very cold… like 5 or 10 degrees for him… he can flip a switch inside his home and turn on that low watt light bulb inside his fig protection… to generate just enough heat to help them get thru that extra cold night.
Some years it may not be needed at all… the wrap is enough… but if a night does come along where he needs that he can flip a switch and turn it on.
I may try that some day.
This is key. Tall, narrow covers like these get minimal benefit from the warmth of the ground, so some artificial heat source is a must. The secret to success is (a) insulation, plus (b) heat.
Z7 doesn’t require much supplemental heat. Many Z7 winters wouldn’t require any supplemental heat at all. A low of 0 F would demand only a slight amount if extra heat. In colder areas, growers use strings of Xmas lights or heating cables designed for pipes.
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We are expecting another cold front coming in Wednesday/ Thursday, winter still here. All my ingrounds figs still green with temps during this months , 9/8/7 and one 5*. All in good shape, but it ain’t over yet.
My tree is housed by 2 five gallon bucket with a light fixture in a 3rd 5 gallon bucket over top for a 30 inch insulated lit system. My tree is a kumquat instead of a fig this winter
My covered figs took very close to 0F some years ago, I had a thermometer under the cover and it was 25F. So as long as you have a good cover which is wide enough at the base to draw heat from the ground you should be good even below zero a bit.
One thing I observed when I had this thermometer was the colder it got the bigger the temperature gap of under vs outside the cover. That is because the “ground heat” is a constant 55F or whatever (varies by location) so there will be a bigger temperature differential ground-air as it gets colder in the air and this will (relatively) make the ground a stronger “heater”…
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The ground generates heat during extreme cold weather. This is why the mulched branches did not receive a lot of cold damage. This the main principle for folks to use the low cordon fig system. When we block the wind and use the ground heat, fig has a much better chance to survive. I do not even have electric access to put some heat source for the fig trees 200 ft from any structure.
If we can preserve about 1’-2’ above ground wood, most fig trees can produce figs.
@scottfsmith – Good observations. I think you are exactly right about an insulating cover that is wide at the base. Your observations of the temperature gain are typical. Larger covers do better than smaller, OTE.
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