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Add perlite?

Posted by TheMasterGardener1 5B (My Page) on
Mon, Apr 2, 12 at 17:14

Hi everyone. Does perlite help air porosity if you add it to peatmoss? I was reading on here it did not? Just wanted to make things clear for viewers.

Promix HP

Air Porosity:
20 - 25 % by volume (6 inch pot)

Promix BX

Air Porosity:
17 - 22 % by volume (6 inch pot)

Follow-Up Postings:

RE: Add perlite?

Just taking a stab at it. Isn't perlite more dense than peat? Not sure how it would improve porosity.

RE: Add perlite?

Promix HP has more perlite then BX for the record. It shows a direct increase in air porosity when perlite is added. Pro mix HP= "High Porosity".....

RE: Add perlite?

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Mon, Apr 2, 12 at 22:00

You've illustrated over and over that you don't understand the physics of water movement and retention in container media, yet you want to argue this point across multiple forums.

I can increase air porosity at container capacity by adding a brick to the bottom of a pot. Imagine a 12x12x12 cube of soil that supports a 3" PWT. That means that 25% of the soil has 0 air porosity at container capacity. Now imagine a 11x12x3" brick at the bottom as part of the cu ft of soil. The total volume of saturated soil is now 1x12x3, or 36 cu" as opposed to the 432 cu" it was formerly. The soil's volume was reduced by 396 cu" by the brick, but after the calculations are done, the 1,332 cu" of soil remaining has less than 3% of its soil saturated at container capacity. Isn't it amazing what that brick did for the soils o/a porosity?!

What did the brick do? It takes up space - same thing the perlite does. Did the brick change the physical characteristics of the soil insofar as drainage (flow-through rate), size of air spaces, or the height of the PWT? "NO" All it did was the same thing perlite does - it took up space - it's just that the brick would be much more effective.

You grab on to these trivial things to try to prove someone wrong, time after time, with no understanding of what you're arguing about, all the while forgetting entirely about the concept or the basic and very simple point.


RE: Add perlite?

So having one brick at the bottom of a mix of 100% peat would DRY up quiker then the same mix with no brick?

Because promix hp will dry quiker then bx.....

RE: Add perlite?

If you look at pieces of brick through the medium like

"So having one brick at the bottom of a mix of 100% peat would DRY up quiker then the same mix with no brick? "

Yea, it would now that I look at it. I just think having a brick will not increase air but will let it dry quiker because there is less volume of peat to be wet.

But they tested pro mix BX and HP in a 6 inch pot and hp had more AIR POROSITY...

RE: Add perlite?

I'm pretty sure that I just lost like a billion brain cells...uuugggghh....head hurts...can't....form sentence....


Note from the estate of PJ: He will not be able to provide any further comments, as his head recently exploded.

RE: Add perlite?

"Did the brick change the physical characteristics of the soil insofar as drainage (flow-through rate), "

I think perlite does in peatbased mediums?

That is the only thing I just do not understand I know the water flows through quiker when there is more perlite in the mix of peatmoss.

What about the "Peat-Lite" mix from Cornell?:

50% Perlite
50% Peat

I used a mix like it and it drained quiker then reg mix.

I found the best mix so far I have used is the 511.

RE: Add perlite?

Will perlite help a peat container drain a little better ?

What perlite does: Perlite with it's built in macropores causes it to expand (becomes bigger in size) when water is added to it, meaning it's intentions are to help retain moisture.

Peat concern: It's very very uncertain and just as unpredictable what your PWT ( perched watering table) will be as nobody (with the exception of you) will know how much water you'll be adding each watering and the frequency of watering you'll be using to grow this plant. Then consider your weather which is oddly unique to your area regarding rain, sunny days temperature highs and lows, humidity ect... and wahhh lahh there you have it. One PWT of an unknown amount.

What is Retention:
Al mentioned a brick, why not just shatter the brick into 1/8 to 1/4 inch pieces? Even though a brick may not /doesn't expand when it's gotten wet rest assured a brick in a container will retain moisture too. A Shattered and spread(Mixed) though out a container VS a single entire brick sitting on the bottom of a container, the amount of water retention of a brick depends on how you use it.

What is Drainage:
The intentions that some mention are rather simple. A faster draining soil that is by coincidence un patented with no legal copy rights for it to be called by any name, a mentioned 5-1-1 will help your plants in container(s) greatly in the prevention of over watering and simplifies the ever complex PWT of most any to APX. nearly all container plant(s) you may want to grow.

All some of us are trying to say is regardless of the soil you may choose, it's a lot easier to drown (a method of killing) a plant at the roots by over watering them than it is to drown the same plant at it's roots by under watering.

To help control a higher unknown PWT provided by peat and so that a container can have a lower PWT that is easier to manage is the primary reason why some choose/ preference a certain custom mix.

RE: Add perlite?

Thanks for adding that mrlike2u. I really see why peat is just not as good as bark. Thanks everyone.

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