Return to the Container Gardening Forum | Post a Follow-Up

 o
Expanding Foam for Lg. Containers

Posted by grancru z5 MI (My Page) on
Sat, Feb 22, 14 at 14:48

Has anyone used expanding foam to fill the bottom of large containers? Is it safe for plants? Does it remain light weight?

I would run a drain tube through the foam for drainage.

Any other easy and light weight solutions aside from packing peanuts and milk/pop jugs that allow for soil to wash down?


Follow-Up Postings:

 o
RE: Expanding Foam for Lg. Containers

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sat, Feb 22, 14 at 15:00

Milk jugs or bricks to take up space in the bottom of your pots are actually better than peanuts or expanding foam. The reason is, they reduce the volume of soil that CAN be occupied by perched water. In doing that, they reduce the amount of perched water a container can hold. Packing peanuts and a layer of expanded foam at the container's bottom will simply cause water to perch in the soil above the layer of material, so all you've done is reduce the volume ov the container ...... and you can do that by using a smaller pot or not filling a pot as full as possible.

If you look at example D in the sketch below, you can see how an over-turned pot or other objects (bricks, empty soda bottles, ....) that take up space at the bottom of the pot reduce the volume of perched water a soil can hold
 photo PWTs.jpg

Al


 o
RE: Expanding Foam for Lg. Containers

Hi Al,

I appreciate the advise. My objective is to reduce the volume of the pot as most plants need 12" or less of soil. Upturned pots still leave excess volume that waste soil.

What I am thinking is filling the container with expanding foam while running a drain tube to the bottom. This should resolve the weight and volume issue once and for all whole retaining drainage. The top of the foam can be shaped for drainage as well.

I have used pots of all sizes, pop/water bottles, ect. as you described for many years and I still find it messy in the fall as well as using unnecessary mix. My only real concern was whether the foam would have any ill effects on plants.

Just wondereing if anyone has tried this and more importantly, successfully.

Thanks again.


 o
RE: Expanding Foam for Lg. Containers

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sat, Feb 22, 14 at 15:26

If you simply insert a drain tube, you're still just creating a smaller container. If you fashion a narrow funnel-shaped depression in the foam that can be filled with the same soil as the rest of the pot (a tapered soil column), you'll have essentially the same effect the over-turned pot offers. It doesn't matter how you get there, only that you apply the concept appropriately.

Al


 o
RE: Expanding Foam for Lg. Containers

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Mon, Feb 24, 14 at 10:59

expanded PU foam is inert. I have used it as mortar in koi ponds and aquariums. It will not hurt your plants at all. It is closed cell so water won't effect it. I don't get the stuff in the cans though. i use a 2 part system so that I can mix up however much I need and pour it quickly and easily. Plus, then you don't have to worry about not using the whole can and having the tube clog up. Also, you can get various densities with the 2 part.

I would put a trash bag in the pot first as a liber before using the foam. That will act as a release if you ever decide you need totake the foam out. otherwise, the foam will be permanent.


 o
RE: Expanding Foam for Lg. Containers

I've used canned foam for various project such as backgrounds for critter cages. I agree with nil13 that it is inert, but I have always waited a few days after using it before introducing critters to make sure that any gasses from the releasing of the foam are gone.
I like nil's idea of the trash bag too.


 o
RE: Expanding Foam for Lg. Containers

hmmmm.....inert or not, I sure wouldn't use that foam anywhere around my food.


 o
RE: Expanding Foam for Lg. Containers

Plants love carbon. Paper is made of mostly carbon. Suggest that you use torn up paper or cardboard to reduce the volume of the soil. Water will drain through and if the roots get that deep they will enter the paper. I usually break up a few twigs and mix them with the torn up black and white newspaper and card board. The wieght of the pot is much less than if you used soil.


 o
RE: Expanding Foam for Lg. Containers

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Tue, Feb 25, 14 at 7:43

Plants get the carbon they need from the air, in the form of CO2. In the soil, carbon serves only as a part of the bond in hydrocarbon chains. Carbon from the soil isn't used, unless the plant just happens to absorb some of the CO2 molecules that gas off as soil particles' hydrocarbon chains are cleaved by microorganisms.

Al


 o
RE: Expanding Foam for Lg. Containers

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Tue, Feb 25, 14 at 10:56

if PU foam submerged in acidic water doesn't effect the fish living in that water, I am pretty confident that it wouldn't effect me after growing some food plants near it and then consuming that food.

This chemophobia thing is getting out of hand.


 o
RE: Expanding Foam for Lg. Containers

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Tue, Feb 25, 14 at 10:59

BTW, they make plant containers out of PU foam.


 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!


Return to the Container Gardening Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.


Learn more about in-text links on this page here