Size is important, weight can be an issue, but where weight or cost differences aren't a consideration, and if size is appropriate, I'd opt for the pumice, even though in some pumice deposits, high pH can be an issue.

I KNOW what JaG is going to say. ;o)

Al

I KNOW what JaG is going to say. ;o)

What? That perlite is a hideous, ghastly, freakish looking white thing that stands out like a sore thumb in a potting mix?

:)

Go for the pumice.

More seriously, perlite is just fine, not every potting mix ingredient can have the same good looks as the sexy Turface and bark. :)

I did a little more research and found that some types of pumice float on water too. In fact floating islands of Pumice 19 miles wide have been discovered in the Pacific, some with plants actually growing on them.
http://en.wikipedia.org/wiki/Pumice_raft

"both hold nutrients"

I believe that perlite holds no nutrients at all. Correct me if I am wrong.

I would go for pumice too, if I could get my hands on some locally...:-)

I'm a hydro grower and I grow tomatoes and strawberries in 100% perlite using static technique (see link).

Perlite is virtually free @ $14 for a 5 cubic foot bag. I buy it at a farm supply store. It comes in three grades. I'd stay away from the fine, powdery one as it tends to clump and clog things up.

The nice thing about perlite is it holds moisture. "My" moisture is laden with nutrient and while the perlite itself does not provide anything (except a little phosphorus maybe), it gathers and holds whatever you stick into it.

When I want to switch crops, I merely wash it for three days in 30% hydrogen peroxide and it's good to go; no wee-beasties and the pristine white color comes back too!

Using it as a soil enhancement would give you the same results and while it is true that it floats, that only happens if you over water and leave standing pools.

It's great stuff.

As for pumice, I've never seen it used for anything except for scraping your heels in the shower. It is a lot more dense than perlite. Both are mined from the earth, but pumice is produced naturally by volcanic activity, while perlite is mechanically heated until it explodes like popcorn.

Hope this sheds some light on each.

Here is a link that might be useful: Static Technique Explained

Mike, it's the pores or cavaties in both the perlite and the pumice that are able to trap and hold nutrients until the plants need them. Neither product provides any significant nutrient input on their own.

If given a choice, I opt for pumice as well, simply because it doesn't 'float' to the same extent as perlite.

I believe perlite has a closed cell structure, so while it does have many pores, they are sealed off and cannot hold any water or nutrients. This is the reason it floats. I think that's what Mike was referring to.

Where does one find pumice? I've found perlite at most stores, but don't think I've ever found pumice.

This outfit in Corona, California sells Perlite for $16 for a 5 cubic foot bag and pumice for $3.85 for a 1 cubic foot bag or $47 for a cubic yard bulk. The trouble is they only deliver in a great big dump truck with a minimum delivery charge of $180. I don't have a pickup truck so would have to have it delivered. They said pumice weighs 900 pounds a cubic yard, so you couldn't carry much more than a yard in a pickup truck anyway. For comparison sake, sand or gravel weighs around 2500 pounds a cubic yard.
http://www.ofwolfinbargerinc.com/plantprices/list.nhtml

I mix perlite and pumice and gravel with the bark, so the look of the perlite isn't quite as distracting. Grey pumice and sharp quartz gravel isn't too bad (for my purposes, at least), and the weight of the perlite and gravel balance out. I do appreciate perlite's ability to lighten the weight of a container.

Sometimes, I'll hold back a small, perlite-free batch of mix to be used as a top-dressing in the container.

Josh

On the pots I have my tomato seedlings in I find putting a quarter inch thick layer of fine sand on top of the potting mix keeps the peat and pumice from floating away when I water the pots. Also makes the water soak in faster.

Everyone here makes a lot of good sense. Seems everyone has great results with both too.

Great help and kind people!

But californian, in the end, it is important for YOU to figure out what "purpose" you are using perlite or pumice for, and why? You can even use both at the same time.

Each has its advantages and disadvantages as was pointed out...

Do you want it to hold nutrients,or to lighten a pot? Pumice is much heavier than perlite..
Do you want to use it for looks? White verses grey?
For the ability to hold its form, or crush over time and disinegrate?
For drainage or for moisture? How much moisture do you want to be held in your soil? Perlite holds alot less moisture than pumice for me.

I question the moisture thing.. If it holds moisture,then why did a soil I accidently made with too much perlite, dry out so fast, on cool days, but even more so, within minutes on warm sunny days? I had to amend it.
How long can a plant survive in a pot with mostly perlite?

I use pumice for moisture, and perlite for drainage.
My pots can go for days without watering, because of the ability for pumice to hold lots of moisture, while at the same time, not keeping the soil "wet" Have you ever heard of "turface". For me it works the same way...
I use perlite for drainage and to keep certain pots light.
In some I use both.

If you can get your hands on both, try growing a plant in 1/2 peat and 1/2 perlite, then 1/2 peat and 1/2 pumice, and you will clearly see what I mean.

Anyway,
I don't know what you are going to use it for.

It is up to you to decide for yourself:-)

Happy growing.....:-)
Thanks everyone for helping out!

jefe, perlite is available in various forms but expanded perlite is used most often for horticultural applications. It does not have a closed cell structure and looks very much like popcorn, with various fissures, cavaties and crevices. Its ability to trap and hold both water and nutrients (in solution) is pretty well established :-) The expansion process is what makes it so light.

Here is a link that might be useful: all about perlite - more than you ever wanted to know!

WOW gardengal,
That is a very imformative article...Thanks! Loved it.
I never knew this of perlite...It certainly has a purpose in life!

Well I didn't see any mention of an open cell structure in that link. It did say that the mineral fraction has a specific gravity of 2.2-2.4, meaning it's ~2.3 times heavier than water and should easily sink if the pores are filling with water. The fact that it floats leads me to believe that most of those pores are impenetrable by water. I believe the only water and nutrients it holds are in the film that clings to the outer surface.

It definitely has some good uses, I just wouldn't count on it to hold additional water and nutrients.

Compare perlites porosity to those plastic foams that are closed-celled. They are quite unlike sponges, which are open-celled. A fair amount of water adheres to the surface of closed-celled materials because of the greater surface area and to some degree, surface micro-porosity, but water won't fill internal porosity as it will in Turface, calcined DE, and to some degree, pumice.

Here's some perlite info, mixed with a little about vermiculite, copy/pasted from one of my previous posts:

Perlite is actually a form of porous glass that is made from a mineral called obsidian (or an aluminum silicate rock). It's heated and kind of popped like popcorn. Vermiculite is mica that is treated in much the same way. Trapped moisture expands and creates lots of air pores in both products.

In soils, perlite promotes drainage and improves porosity. It's also effective for starting seeds & cuttings. Actually, perlite holds quite a bit of water @ about 3/4 quart per gallon of perlite. The dry weight of perlite is about 7 lbs/cu ft. Wet, it weighs about 18 lbs for the same volume, so it holds more than 2-1/2 times it's weight in water. Vermiculite is about the same density, and has a even higher capacity for holding water and a very high cation exchange capacity. It also contains magnesium and potassium that are available for plant uptake, but it is not very durable and will compress if handled when wet. It also has a slightly higher pH than perlite.

Al

Californian,

where in Corona Ca is the place you talk about the carries pumice and perlite? What is the place called? I would like to go buy some. Thanks

Orange County Farm Supply sells 50 pounds of pumice for about $8.00. They are located on Chapman Ave. in Orange, west of Main St. Right across from McDonalds. Just bought a bunch for home and school so price is current.

I think I'd probably opt for pumice, too, if I could find it locally without breaking a sweat, but coarse perlite is easier to locate in my area.

The only problem I find is no matter what size you get, there's an awful lot of dust and smaller pieces to be sifted out.

Perlite does tend to float, but I find it mixes fairly well without incident if I soak it down first, along with the other ingredients to create a nice pre-moistened/pre-soaked medium that's drained off and mixed well before potting.

Perlite is used to aerate and improve drainage. An per my observation it has no or negligible porosity to hold water. If it cannot hold water won't hold nutrients.

If you want moisture retention consider some kind of floor dry. I have tested and used UltraSorb from O'Reilley Auto Part. On unit by weight of it will absorb roughly the same amount of water. And it will hold its form. I froze it , thawed it . Did not budge. So in my 5-1-1 I mix it instead of perlite. Once it is saturated , will act more like perlite, or turface.

Sey

Hi! My names Lexi & my family just recently purchased and renovated the only 2 Pumice mines in California.

I was reading through the comments and saw how difficult you all have been finding it to get your hands on pumice and wanted to let you know that's no longer the case! Since our family is now in charge of the mines, known now as "General Pumice Products", we have mining rights for the next 200 years and can actually ship 15lb. bags of 4 different sizes of pumice straight to your front door! We also sell in bulk and wholesale to nurseries like Altman's, Monrovia, Color Spot, etc.

Go to our website for more information and to order!

Thanks so much.

Call me with any questions 760-403-4718

www.GeneralPumiceProducts.com

Nice site can you post a couple pics with coins for reference of the available pumice sizes that you offer ? BTW I noticed the horticulture tab/ page on your site stating that pumice is pH neutral.

How much to deliver a couple cubic yards to LA?

Nomen_nudum, thank you! And absolutely!

Here's our smallest size 1/8"

Our next & most popular size 3/16"

And our larger, special order size 3/8"

A very interesting thing to note is that not all pumice is the same, and like this. Only 3 mines in the United States have this specific type of pumice that is pH neutral, packed with Zeolite (which is a water purifier & detoxifier for plants and your body actually), that has no boron (which will turn your plants yellow), and is completely dry. And my company, happens to own 2 of those 3 mines.

This is why it is so important to know where you are buying your pumice from, what the pumice nutrient content is, where it coming from (pumice from Oregon is very dense, brown, and very wet due to the rain fall, and does not have the mineral/vitamin content our product does.) This is why I would avoid buying on Amazon unless you know the seller's product quality very well and have all the above information from them.

Looks great!

Josh

Nil13 great question!

We can ship in bulk 2000lb. pallets that have 25lb. or 50lb. bags of product, or we do 2000lb. totes. One pallet is about 2.5 cubic yards, and for 1 pallet delivered to LA we would charge $450. For 2 pallets delivered. $425/pallet, 3 pallets $400/pallet. The more you purchase at once the better price we can give you.

We also sell 15lb. bags on our online store (15lb. of our pumice equals about 4 gallons to give an idea of volume) for smaller outfits/personal home use. We ship 15lb. bags anywhere in the US. for $20.00 for 1 bag, 2 bags for $37.00, and 3 bags for $54.00, FREE SHIPPING for any number of bags ordered.

Yikes!!! I think I'll stick with local distribution.

the Pumice can be used as a substitute for the turface or the granite in the gritty mix ?

I reduce the use the use of clay products such as napa oil /floor dry turface. Granite chips ( sifted and sized) breaks down a-lot slower than the clay materials.

Some pots here are apx 97% pumice and pumice type materials called scorsa, lava rock) with some organic matter composing the rest.

Nil,

I think those prices seem high because they all include delivery charges. We are fortunate to live close to wholesale bulk suppliers that have this product at very low prices if you pick it up. Their product looks like it is cleaner than what I buy from OF Wolfinbarger.

I see the benefit of their product for retail consumers in other places that need a small quantity delivered to them. Also a nursery that wants a pallet to resell a bag or two at a time.

Hello,

Never used pumice, planning to use it in a GMX to replace the Turface.

My big unknown is about the right size of this pumice stone that I will order: 2-4 mm or 4-8 mm?

I was somehow under the impression that anything under 3mm in the GMX is not a good ideea. I would really like to avoid sifting out a big amount of the bag because is under size.

What would you do? 2-4 mm or 4-8 mm? (coin size: 15 mm)

2-4 mm

or

4-8 mm

Thanks,

Michael

In
a perfect world, the mineral fraction for use in the gritty mix would
range in size from about 1/10 - 5/32" (.100 - .156" or
from about 2.5 - 4.0 mm) The bark fraction would be slightly larger
to allow for some breakdown over the life of the planting ........
from 1/8-1/4 is about ideal (.125 - .250" or about 3.25 - 6.25
mm.

I'd opt for the 2-4mm and screen it through insect screen. If you essentially get noting passing, you can skip the screening; although, I DO screen all 3 products (Turface, grit, bark) over insect screen, even if the product is prescreened, to rid it of dust which collects at the bottom of the pot as sludge.

Al

Thank you so much Al:)

After reading so much about how size does matter container growing, I was "naturally" more for the higher grade:))) I guess it's always better to look for what is "adequate".

I already spotted an insect screen, I will surely go through this step, since I plan to leave the trees in the new pots for at least 2 seasons and would like to avoid accumulation of sludge.

Meanwhile, I struck oil & gold and ordered 20 GAL of washed pumice (2.0-5.0 mm grade) from Germany. Also at a decent price.

Bark & perlite are ready. I'll just wait for the spring and hopefully will not overwater to death my trees until then.

Thank you once more,

Michael.

nice to see this ol' thread again … like a long lost friend ...

Looking for a clarification to this old thread that keeps giving:) ... [ @tapla needing advice on possibly slightly changing up Gritty mix after lugging all of my succulent pots plus my 3 FLF trees in and out of my Houston home over the last 3 mo (in when temp dropped into 50' and then back out 2 days later when we are back @70-90 deg winter days cycles ). It's been worth the hassle for sure since I'm almost one year into my mission to quickly grow these Home Depot one pot/ two tree FLF" bushes" into beautiful indoor 7-9 ft trees so letting them thrive acclimated to hours of afternoon direct sun outside since purchase. I repoted one bush into two trees last May/ June into true Gritty and I need to repot my last "bush" this May into two separate pots to move to Gritty and curious on what your thoughts are on adding a fraction of perlite to the original Gritty mix to take away some weight in the size pot I want to use (roughly 14"x12") would you think that is "okay" / and if so what breakdown of fractions do you recommend? And if not okay, maybe verse me in your knowledge and thoughts why as I've been blindly experimenting with perlite my succulent propagating....

I've been having trouble getting some species of succulents to root in Gritty mix / esp difficulty getting propagated leaves to grow roots on GM as well as they do in soil( I usually spray well prop.succulent leaves with spray bottle every 2-4 days so Gritty issue for this purpose likely due to me not spraying/ watering daily and surface too dry for the callused ends. I get terrific roots but occasional leaf rot propagating on soil So I've been experimenting w mixing perlite with cactus soil and a small fraction of Gritty mix ( random I know - just literally grab a handful of each ) and so far it seems to be working well so this is what got me curious on the repot of the FLF. I'm sure it helps to note that I do not desire to need to water anything daily since I'm out of town on weekends often but do like being able to check in w plants and water weekly to biweekly. The FLF's I have in Gritty do well outside ( high humidity) with only weekly, thorough, watering. Maybe it's our constant 70-90% Houston humidity ( plus plants stay semi sheltered under covered patio) but I only find my Gritty gets dry to touch one to two inches down by day 2-3 in the hot summer months/ otherwise it's Usually still slightly damp under the surface 2 days later even though water in pot drains quickly in large quantities within seconds of me watering. Hope that all helps you offer me more of your expertise!

Pumice can be found at any horse supply store.. ( it's used in the horse barn ) It's called Dry Stall and sold in 50 lb bags for around ten dollars . ( 100%pumice) You might have to rinse some of the dust particles out, but it is all Pumice.

I can find it at Southern States and Tractor Supply Stores and I know that any place that sells products for horses will carry this and or they can order it for you!!!

Laura

Also Dri Stall offered at local feed stores in Orange County Ca, smaller grade sometimes. But good price. Good mulch, and seed topping. Use Dri Stall for soiless mixes for Natives, and Plumerias etc. Pumice or Perlite used in Forestry Nurseries as Seed topping

Would 1/8 pumice or the 3/16 size be better in the mix?

I prefer 3/16 for gritty mixes.

Hi Fred!

Another New Zealander here. You may be long gone but just wanted to say hi and thanks for doing that great experiment. I would have thought it was more the bark too. Go pumice!!

Cheers

Robin

@General Pumice Products is your pumice mine producing the pumice used in the Dry Stall product?

Just an update for anyone following this thread who has purchased or wants to purchase General Pumice's product we have changed our website domain! It is now www.GeneralPumice.com ! Hope that's helpful!