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Best way to keep containers cool in summer sun

Posted by briana_2006 IL (My Page) on
Sat, Apr 26, 14 at 15:54

Hello All -

I don't really have good sources of shade in my yard for my container plants - figs and other fruit trees.

I have thought about wrapping the containers in reflective mylar sheets or perhaps aluminum foil to reflect sunlight off the container bodies to keep them cool.

I am concerned the container soil is getting too hot and slowing growth of the plants.

Any ideas?

The current containers are grayish and plastic - approximately 11 gallons in size.

They are in the sun essentially all day from sun up to sun down.

I am planning to change the pots this year to black nursery containers - 15 gallon or 25 gallon.

Thanks for your help

Brian


Follow-Up Postings:

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RE: Best way to keep containers cool in summer sun

I think the black pots only draw the heat, I would use only white if I were you. I'm sure others will give you more advice. Good Luck.


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RE: Best way to keep containers cool in summer sun

Hi Christine -

Thanks for your reply.

I forgot to mention in the previous post I am unable to find this size that is made out of a light plastic in white.

The black ones are also readily available and cheaper than similar sized ones available from other sources that are either heavier or that don't have a good shape - almost cylindrical.

I agree the black will draw even more heat.

I'm hoping for a good idea to manage the heat in those containers.

Thanks,
Brian


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RE: Best way to keep containers cool in summer sun

Can you paint them white?


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RE: Best way to keep containers cool in summer sun

I think krylon makes a spray paint for plastic?


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RE: Best way to keep containers cool in summer sun

You might consider fabric containers, like smart pots. They were developed by the nursery industry for raising trees. And several scientific studies have found that they keep soil temperatures much lower than solid containers, even when they're black. They do that through evaporative cooling through the sides of the container. There are several different brands, and you can find them in lighter colors. They aren't that attractive, but in larger sizes they are fairly inexpensive compared to other kinds of pots. I use about 20 of them in sizes ranging from 10 to 25 gallons for summer vegetables.

This study is about cold temperatures, but it also discusses high temps.

Here is a link that might be useful: Winter survival in fabric pots


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RE: Best way to keep containers cool in summer sun

I think the slow growth might be because they are in containers. How long have you had them that you are noticing their slow growth?

Trees in containers can still get root-bound and they will begin exhibiting problems related to that, including not fully reaching their potential.


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RE: Best way to keep containers cool in summer sun

I was going to use plastic containers and then I remember that perhaps I burned the roots the last time. I'm not sure. I was going to use 32 gallon barrels. I have one I've been using for compost and lugging things around I drilled up like swiss cheese. What if you drilled holes and wrapped the containers in weed guard? Don't do it without consulting others though I'm just brain storming P

I was going to make my own fabric containers out of the thicker weed guard or many layers of the thinner stuff I have on hand. I figured pvc frame and wrap the frame and perhaps use thick jute or even wire to hold the fabric in place. Should be too expensive. The gray conduit pvc has uv resistors and wont break down. Almost all those containers they sell at the home centers have little resistance to the big fire ball in the sky. I can show you how they crack up like chips after a while.


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RE: Best way to keep containers cool in summer sun

I have the same problem. I have tried wrapping light-colored fabric around the pot (I used binder clips to keep it on) and that seemed to help.

I am also planning to try to double-pot them -- put the plant pot inside a bigger empty pot -- and maybe wrap the outer one too. I can't see why it wouldn't work. (Assuming I remember to have plenty of drainage, and put a few rocks under the plant pot so it won't sit in water inside the bigger pot.)

I also raise the pots off the floor surface, since that conveys heat too. I just use rocks.

The bigger issue is, my roommate likes things to look nice, and I'm not sure this will! Uh oh.


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RE: Best way to keep containers cool in summer sun

I have the same problem. I have tried wrapping light-colored fabric around the pot (I used binder clips to keep it on) and that seemed to help.

I am also planning to try to double-pot them -- put the plant pot inside a bigger empty pot -- and maybe wrap the outer one too. I can't see why it wouldn't work. (Assuming I remember to have plenty of drainage, and put a few rocks under the plant pot so it won't sit in water inside the bigger pot.)

I also raise the pots off the floor surface, since that conveys heat too. I just use rocks.

The bigger issue is, my roommate likes things to look nice, and I'm not sure this will! Uh oh.


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RE: Best way to keep containers cool in summer sun

  • Posted by bcskye 5 Brn.Co., IN (My Page) on
    Sun, Apr 27, 14 at 23:08

Usually you can go to the bakery department of some grocery stores and they will give you their empty containers that their icing comes in. They are white and big. I've used them to plant several different veggies in. Black absorbs heat and white reflects it. Learned that in school back in the dark ages.


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RE: Best way to keep containers cool in summer sun

Already commented:

--- avoid black , grey any any matte textures.
--- use white, light color shiny outer texture to reflect heat
-- try to place your pots somewhere the there is good air movement.

It is the early morning and late in the afternoon that sun shines on pot. During most of the summer days the sun is up way high and the plant's own foliage should shade the pot.


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RE: Best way to keep containers cool in summer sun

Just thought of another thing.

How big is your yard? Perhaps it would be worth it to plant a tree (or large vining perennial) for shade.

That tree can then provide shade for all the other trees in pots that you do want to focus on and grow.

You could also create a quick shade by making some kind of wall. It may not jive with your yard but it's all for the better of the trees!


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RE: Best way to keep containers cool in summer sun

  • Posted by mksmth oklahoma 7a (My Page) on
    Mon, Apr 28, 14 at 11:49

I have been painting my nursery pots with Krylon Fusion. either white or beige just whatever I get. works great for keeping them cooler. The paint will stick pretty good if you prep the pots well. I t can scratch off if you arent careful.

mike


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RE: Best way to keep containers cool in summer sun

I've been wrapping my containers, including the fabric Smart Pots, in blankets cheap ($1.50) reed blinds I found at the Daiso Japan stores to keep them cool.

We'll see how they work with temperature here in Southern California being broadcast for 95-106 degrees over the next 4 days.

Daiso has a number of stores in California and Washington State. I don't know about the availability/price of these things elsewhere but if you have one of these stores nearby, it's a good place to find some cheap material. I personally think they look pretty good (more natural than a mylar, at least-- not sure how I feel about shiny metal surface on my garden containers :)). More to the point, the dried reed are light colored and hollow so should help block the direct sunlight from the container.

Linked below is a picture of a container I wrapped in the reed blind blanket. I took the blinds, cut it down to size, wrap it around the container and tie things up with either strings or zip ties.

I also have a few containers (plastic ones and Smart Pots) on concrete (these are the spots with the most sunlight in the smallish yard). I put a piece of one inch thick plywood between the concrete and the container. Maybe not the best solution but should help somewhat.

Here is a link that might be useful: Container wrappedin reed blinds

This post was edited by DHLCAL on Tue, Apr 29, 14 at 1:27


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RE: Best way to keep containers cool in summer sun

I have my containers placed together so that they shade one another. Around the perimeter, I drive wooden stakes into the ground, to which I staple shade cloth which is cut in a strip high enough to cover the container but not the foliage. Obviously, this requires sorting pots so that similar sized pots are next to each other.

Alex


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