Is there a maximum amount of heat a fig tree can take?

I tried to figure it out last year when my Alma fig would not ripen any figs they just all got a certain size and stayed that way for four months. I think it was in the mid 80's. I moved it to the concrete driveway which has white reflective paint and so does the garage door.

I measured the temperature again and it was 115 degrees in the shade since the cement was hot and the white paint from the garage door reflects more light onto the cement making it even hotter. Within 3 weeks all the figs turned yellow and were dripping honey from their eyes.

I'm thinking of recreating that experiment on a larger scale to try and ripen some of the higher heat required figs, Figo Preto, Cole De Dame Gris being two.

Does anyone know what is too hot, like it will damage the plant. I was thinking of going even higher like 120-125 degrees. I know the middle east can get that hot...

Will they get damaged from that higher temperature? Any suggestions from you hot climate dwelling folks?

Here in my yard I have a temperature sensor. In the past 3 years my measured ambient peaked at 117 F in the summer. AZ in the summer is also very cloudless so the direct solar is extremely intense. I also have 'rock mulch' (basically a gravel yard). And since it is light in color there is a lot of reflected light and heat off the ground (so depending on the time of day the trees are almost getting 1.5 suns). Kind of similar to your driveway / garage door experiment. So far the figs show no sign of damage (properly hydrated of course). I suspect they can go higher still, maybe even into the 120s like you are thinking.

From my limited experience , the trees will be fine to a quite high temperature. Where you need to be careful is the temperature of the containers. They need to stay cool and nicely watered. I measured the temps of the pots a while back, they can be protected relatively easily.

http://figs4funforum.websitetoolbox.com/post/measuring-the-soil-temp-in-the-pots-6480114?highlight=pot+temperature&trail=50

You have to watch out for the roots getting too hot. That will stunt growth. I went through that this summer in Pennsylvania... and didn't have any growth for 2 months. http://figs4funforum.websitetoolbox.com/post/summer-dormancy-improvements-6438722?highlight=summer+dormancy&pid=1288213211

Thanks for the links and comments.  @starch: Thanks that is what I wanted to hear. :)

I think my design will reduce the problem of the pots heating up.  The focal point for the incoming light should be higher than the pots.  I will still paint my black pots white to make sure they don't get over heated.  I will make sure they stay in within this range for normal root growth. 
(50 deg F to 80 deg F   = Normal root growth.)  

Its a parabolic mirror greenhouse design.  Similar to what this picture shows.   




http://montessorimuddle.org/wp-content/uploads/2012/01/Parabola_with_focus.png


My hope is not just to get a perfectly ripe preto, panachee and cole de dame gris.

 But to possibly get 2 or maybe 3 main crops to ripen each year.

 Ill be sure to post pictures of it when its done and most importantly of ripe figs.  

Sid, that is a cool idea! (...er, hot i mean) :) Let us know how that turns out!

I would be interested to see what temperatures you to. I am also wondering if it will concentrate too much. This design is basically one of the methods that CSP solar power stations (focusing the sun on a fluid line to collect heat which heats up the fluid and drives a thermal gradient which can then move a turbine) use. I have seen them in AZ out past Gila Bend. They use highly polished parabolic reflectors and can get the line temperatures up in the hundreds of degrees. I would definitely stick with white paint for your first iteration which is reflective but not as reflective and specular as polished metal. Good luck!

Going past 120F is getting dangerous. I don't see any advantage to going above 100F. But it's difficult to measure exactly what the plant is experiencing. I'd not be in favor of any kind of parabolic reflector to concentrate the heat. Just a few minutes too high could result in cooked figs and fried leaves.

I think that the best way to find the answer is by doing multiple experiments at the same time.

Let's say I start at 90F and go up by 5F increments up to 120F. Let's say 7 fig trees each in a different section that is 10x10 that has a temperature guage and a fan that will automatically turn on if the temperature exceeds the max and turns off when the temperature is cooled by 5F. The figs of course will be the same variety, age, soil, and pot size.

This experiment is only going to be done to see what happens to ripening figs. The idea is to find out the optimal temperature that will produce the best tasting figs and if it is possible to hasten ripening without sacrificing flavor by raising temperatures.

If the 120F fig starts drooping and the leaves start to burn I will remove it. It makes sense that there is a certain amount of solar radiation that they can endure, before it becomes detrimental.

At the highest temperature I may use concrete walls to block some of the light, instead letting the radiant heat from the concrete, heat the plants instead. Once the perfect temperature is found I can use that information to create the rest of my greenhouses with that number in mind.

Thank you everyone for you input.

It will be interesting to see on how heat affects fig growth and ripening.

I think excessive heat will have a major impact on the tree growth and quality of the figs ripened. 
It may not all be good news. 
Many plants shutdown when it is too hot and stop growing.  The ripening process can also be derailed at certain temperatures. 
The ripened fruit can be affected by a spike in sugar production and associated drop in acids. 
This lopsided balance could affect the taste of the fig and may affect processing such as jams and other fig preserves.

Will you have a baseline of figs grown at regular temperatures to compare to? 

@Pino: I am doing this hoping to find the right temperature where there is a perfect balance of sugar to acid ratio. If that temperature is 100 degrees then I will be happy. As it will be easier to maintain 100F than 120F.

My 1st fig variety to try will be Figo Preto, I have 30 of them now growing and they are all the same age. I will select 7 that are closest in size once they have their first figlets forming and move them into the separate heated greenhouses. I should have 23 left to be the baseline and they will ripen at 70-77 degrees summer heat most likely.

This is just a heat experiment, other factors could effect the flavor, such as PH, N.P.K ratio, micro nutrients and the breed of my neighbors dog even, from what I've heard. :)

More experiments will be done to figure out the rest of those factors later.

The only one I might have difficulty with is figuring out the breed of my neighbors dog, as he is a mutt... Do they have a dog version of ancestry.com???

@figgysid1: I'd rather control the humidity rate in the greenhouse than the breed of the passing by dogs.
When it is time to grow the tomatoes, I add a bucket of water in the greenhouse. With the heat, that water will evaporate and reach the leaves of the plants and (IMO) help them take better advantage of the heat. The humidity will reach the greenhouse's walls and filter some sun.
If you don't add the bucket of water, you may dessicate the leaves from the dry air. Like hot air coming out of an hairdryer.
A bucket of water to provide humidity will help, and is not related to the temperature ...
If you have two greenhouse, run that test too ...
Having the trees well watered will help too. What is your plan for the water supply to the plants ? Free access to water ? Restricted access ?
Good luck and keep testing !

I think the best guide for greenhouse growing would be to mimic those natural climates where the best figs are grown. Those climates are sunny, warm, and dry in summer. High temperatures seldom above 110F and average 90-100. Excess water and humidity lead to watery figs. If that's how you like figs then fine. But that's not how figs are in dry summer climates like CA or Turkey or similar areas.

My greenhouse is set up to mimic central CA where summer highs average upper 90s but I think 90F is high enough. That is better than 77F IMO.

@jdsfrance: I forgot the humidity part.  I am using 5 gallon trays of water under all my fig trees, that should provide adequate humidity. As for water access there are 15 streams that flow thru the property anytime it rains more than 1-2 inches.  I will get digital humidity monitors as well, is there a certain amount of humidity I should be trying to achieve?  My goal is to get 60 greenhouses up so I can do as many different experiments as I can at the same time.  Then when all the experiments are finished, all of them can be adapted to be the "perfect ideal conditions".    

@fignutty:  Mimicking the natural climate that figs grow in makes sense.

 But sometimes plants will grow much better in conditions different than their natural climate.  Some invasive species that have been introduced to Hawaii grow poorly in their natural climate, but when they are grown here they become monsters, they take over 1,000's of acres, grow many times faster, produce 10x more fruits/seeds since they are tricked into thinking that it is spring all year so they produce fruit all year long instead of just 1-2 months out of the year like they would in their natural climate.

I will post my findings of each experiment.

Thanks for the comments and ideas.  

Rampant growth is great if growing certain veggies. But it's not best for most deciduious fruits including figs, unless you're growing leaves for tea. Most of these fruits produce higher quality fruit with moderate vigor and low humidity.