Post a reply

Are Vermiculite and Perlite the Same?

By drdawg
January 25, 2015

It seems that many people believe that vermiculite and perlite are similar products used for similar purposes. This is not true.

[View the item]

Image
Jan 24, 2015 8:27 PM CST
Garden.org Admin
Name: Dave Whitinger
Southlake, Texas (Zone 8a)
Region: Texas Garden Research Contributor Million Pollinator Garden Challenge Charter ATP Member I was one of the first 300 contributors to the plant database! Garden Ideas: Master Level
Region: Ukraine Garden Sages Plant Identifier Avid Green Pages Reviewer Vermiculture The WITWIT Badge
Soils or medium with a high cation exchange capacity (abbreviated CEC on soil tests) means it can attract and hold onto large amounts of cations with the opposite charge. This translates to soil that can hold nutrients rather then leaching them right out.

Vermiculite has a good CEC value while perlite has almost zero. This means that generally speaking a potting soil mix with vermiculite will hold nutrients better than soil without it. The same is not true of perlite.
Image
Jan 24, 2015 9:05 PM CST
Name: Ken Ramsey
Vero Beach, FL (Zone 10a)
Bromeliad Vegetable Grower Region: United States of America Tropicals Plumerias Orchids
Region: Mississippi Master Gardener: Mississippi Hummingbirder Cat Lover Composter Seller of Garden Stuff
My main goal in using perlite is not to hold nutrients (and thus, water) but to allow better and faster drainage. I also want my soil to be more open, and allow passage of air more readily. I simply believe that this is what's best for my tropical plants.
drdawg (Dr. Kenneth Ramsey)

I don't have gray hair, I have a lot of wisdom-highlights. I must be very wise.
Image
Jan 24, 2015 9:59 PM CST
Name: Dirt
(Zone 5b)
Plant Lover: Loves 'em all! Region: Utah Bee Lover Garden Photography Million Pollinator Garden Challenge Photo Contest Winner: 2014
Photo Contest Winner: 2015 Photo Contest Winner: 2016 Photo Contest Winner 2018 Photo Contest Winner 2019 Photo Contest Winner 2020 Photo Contest Winner 2021
dave said:Soils or medium with a high cation exchange capacity (abbreviated CEC on soil tests) means it can attract and hold onto large amounts of cations with the opposite charge. This translates to soil that can hold nutrients rather then leaching them right out.

Vermiculite has a good CEC value while perlite has almost zero. This means that generally speaking a potting soil mix with vermiculite will hold nutrients better than soil without it. The same is not true of perlite.


This almost implies that vermiculite is 'good' and perlite is 'bad'--
Really, the goodness or badness of either is multifactoral and dependent on the desired outcome(s)...sometimes it is desirable to hold cations and sometimes it really isn't.
Not all charged particles are 'nutrients'...and not all 'nutrients' are positively charged
Cation= positively charged particle (i.e. Na+)
Anion= negatively charged particle (i.e. Cl-)

Vermiculite does have a high CEC ~100-150 meq/100 g (incidentally, significantly greater than any of the soil types listed in this guide from Purdue)

https://www.extension.purdue.e...

for more than most people want to know...
Image
Jan 25, 2015 6:59 AM CST
Name: Ken Ramsey
Vero Beach, FL (Zone 10a)
Bromeliad Vegetable Grower Region: United States of America Tropicals Plumerias Orchids
Region: Mississippi Master Gardener: Mississippi Hummingbirder Cat Lover Composter Seller of Garden Stuff
Good points, Dirt. We could use builder's sand, gravel, pumice, bark, and several other things to improve drainage, but because of the "lightness" of perlite, because it is readily availabile, and because it is so inexpensive, I really couldn't do without it.
drdawg (Dr. Kenneth Ramsey)

I don't have gray hair, I have a lot of wisdom-highlights. I must be very wise.
Avatar for Oberon46
Jan 25, 2015 12:05 PM CST
Name: Mary Stella
Anchorage, AK (Zone 4b)
Dahlias Canning and food preservation Lilies Peonies Permaculture Ponds
Garden Ideas: Level 2
This is the best information on the perlite/vermiculite discussion I have read to date (including Ken's original article.) I will have to print them off for reference since no way will I retain all this. Wish I had a photographic memory. Thanks bunches for all contributions.
You must first create a username and login before you can reply to this thread.
  • Started by: dave
  • Replies: 4, views: 6,377
Member Login:

( No account? Join now! )

Today's site banner is by RootedInDirt and is called "Echinacea"

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.