The summer here in northeast Kansas as been the hottest on record with many weeks above 100 degrees, reaching 107 a few times.   I grow most of my figs in containers and definitely noticed a drop in productivity and growth in many of them.   Core soil temperatures were embarrassingly and outrageously high during the worst weeks of these extreme temperatures.  

Fortunately I did not lose any figs during the wretched heat.  Daily watering kept them moist and cooled them down mid-afternoon.  (my watering help, a trusted neighborhood high school senior kept them alive while gone during some of the worst heat)

Some cooler weather just moved in about 4 days or so ago and am noticing an amazing outburst of growth.   More evidence supporting the need for moderated/cooler soil temps.  

Searching through the discussions I found many common sense solutions.   Growing in the ground of course solves most soil temp issues but there is the winter cold issue...    I found the following recommendations that could work for containers:

1)   Pile straw around and on top of the pots.
2)   Pile a thick layer of mulch on either side of the pots. (my favorite)
3)   Use an insulated container (feasible for a small collection
4)   Wrap foil around the pot (feasible for a small collection
5)   Cut strips of thin styrofoam insulation containing a reflective layer of aluminum.  Place on the afternoon sunny side of pot to reflect sunlight.
6)    Any additional recommendations??

Burying the pot deeply may result in drainage issues or problems digging it up after it makes roots.  The first two recommendations might be best for a larger collection and am considering the mulch method for next season.

I read in a posting that a root zone temperature of 85 degrees was approaching the upper temperature limit for roots to perform their best.    What is the source of that information?   Are their other references or personal experience to document this?   Just curious.

  Most issues are under control these days (pot size, root pruning, soil, watering, nutrients, pruning, propagation, etc.)  Cooling the roots is the goal next season. 

Ingevald

Cut shade cloth, and drape over top and sides of the containers to keep them in the shade.  Secure with clothespins.  Tacky looking, but effective.
Suzi

Suzi,
    What a great idea!  I actually saw this the other day and forgot to write it down.    I just did a quick search and see that varieties of white shade cloth exist which I think would keep the situation even cooler.   I am not worried about tacky right now.  Effective and practical solutions are what I am seeking.

Thanks,
Ingevald

I can't address figs, but had the same problem with the +/-50 blueberries I grow in 15 gallon pots. Of course it doesn't get as hot here, and bb roots are less aggressive and much finer. And the bbs stay outside year-round.

But, this has worked out very well. I buried the pots partially into the soil and then mounded the dirt from the hole around the base of the pot. But that still left about 6 or so  inches of pot exposed, so I covered that with free city mulch, which is brown in color. That made the plants look as if they were inground and you could not see the pots unless you looked. Functionally I don't much care, but they are in the front yard. It looks better, and makes it less likely that anyone is going to steal my nice potted blueberry plants.

This definitely keeps the pots cooler and reduces the urgency for watering quite as often. And it wasn't that difficult to do at all.

I thought it was just my trees, but I had catatonic fig trees for much of July...when the Summer temps. were the hottest.  They just sat there, and roasted...like I did!  I didn't know if the trees would drop all the forming figs.  I believe this was because of overheated containers, and heat-stressed roots.

Now that the temps. have dropped, the fig trees resumed growing normally and my figs are starting to ripen.  This year more than others, I have tasted some of the sweetest, honey-clotted figs that my trees have produced.  This year, I drastically cut down on water at the roots as the figs are ripening.  Easy when you grow in containers.

I think that preventing the root zone from getting heat stressed is the key to containerized culture, and remedy #2 is probably the easiest  way to help reduce the temps. of the containers.  Had I the dedicated space/land for growing figs, my containers would go partially into the ground, roots would be allowed to roam ionto the cool soil, and the containers would be heavily mulched to conserve moisture, and shed heat.  Cool roots, warm, sunny, tops.

I have yet to learn all the secrets of fig culture in less than ideal areas.

Frank

My figs have done fantastic through all months of 100+ heat which started around April/May and now hotter than ever.   Only lately since temps reached 120 that I got just a few scorched leaves.  I've had robust growth on all of them in the heat and most are in black pots sitting on the patio with a lot of sun during the day.   Maybe mine are used to the sun and heat, but most of these are cuttings I started this year around Feb-Apr.   Maybe if you are in an area that doesn't get intense sun so consistently, they aren't used to it and get scorched.   I think it's the sun more than the heat that can roast the leaves quickly.   I haven't tried to boost growth with synthetic fertilizers so that helps to not weaken them when other stresses around.  

Figfinatic - thanks for your thoughts on the situation.   I have been thinking about your situation and am impressed that they have grown well until it really got hot.    

    My figs are in the sun most of the day.   I do not have any scorched leaf issues at all.   Many of my fig plants just went idle during these many hot weeks - no new growth.   The recent cooler weather has resulted in a surge of activity.   

  I am impressed and slightly mystified by the growth you are experiencing.  Since this are new starts, I assume they are in 1 gallon or slightly larger pots?

Thanks,
Ingevald

I noticed the same thing when I was growing in containers and now growing in the ground.  The trees go into something like a summer dormancy.  Sometimes the tips stay green, but all the leaves fall off.  Last year, my in ground trees put on no growth between June and mid-September.

One method to keep the root zone cool which has not been mentioned is putting the pot in a larger pot (clay if available), then filling the void with a coarse mulch.

~james

One of the things I do is to put the  pot inside a white pail that is just big enough for the  pot to fit into
I have also painted some of the black pots silver.

Grant

Z5b

James,

    Would I be correct to suggest that by wetting the mulch and clay pot, one could reduce the temperature even more?

Terra cotta actually cools itself, the way Ken does it is to leave the pot sitting in a shallow tray of water. It works by the "swamp cooler effect" or evaporative cooling.

I planted a few trees in grain sacks made of woven nylon (the type used for bird seed etc.) and was really impressed at how cool the roots stayed. The bags are white but also breath and cool themselves through evaporation. The downside is that they need water more often.

Ingevald:  I was thinking that if these fig plants can take superhot temps here (100+ for months on end) in daily sun in black pots on concrete, then don't waste money worrying so much about the roots in other parts of the country.   My figs are not from here either.  I got them all from places in the country cooler than mine.   I had most of mine in half gallons, but they got so big that I transferred some of them to 3.5 gallon white buckets the other day.  The only scorched ones were the ones in the big pots that I accidentally sprayed water on in the morning and I guess when the sun came up, they weren't dry yet. 

Along the learning process, I failed most when I used verimculite and or soil that retained a lot of moisture.  I figured that it was so dry here that I needed stuff that retained a lot of moisture.  Boy, was I wrong about that.   Nothing was growing and they were dying.  The mix most people use 50% regular potting mix/50% perlite works great in this climate too.   I also add compost sometimes as the soil settles.