Vermiculite and Perlite

I know vermiculite is used to top dress seed trays to retain moisture, but what is Perlite used for?

Steve...

 

"Perlite is a naturally occurring volcanic rock which is used to aid aeration in seed compost and also to add better water retention, often used in hanging baskets, an added bonus is that it’s virtually PH neutral."

Extract from my plant propagation unit assignment for college:wink:

 

They are much the same thing as i was aware and used for the same thing. Water retention and airation.

 

Vermiculite is a naturally occuring, non-toxic aluminium iron silicate mineral that has been heated to a high temperature to produce a lightweight material with a high surface area,Vermiculite holds water.
[FONT=Arial,Helvetica]Perlite is not a trade name but a generic term for naturally occurring siliceous rock. The distinguishing feature which sets perlite apart from other volcanic glasses is that when heated to a suitable point in its softening range, it expands from four to twenty times its original volume. [/FONT]
[FONT=Arial,Helvetica]This expansion is due to the presence of two to six percent combined water in the crude perlite rock. When quickly heated to above 1600°F (871°C), the crude rock pops in a manner similar to popcorn as the combined water vaporizes and creates countless tiny bubbles which account for the amazing light weight and other exceptional physical properties of expanded perlite,as opposed to holding water as Vermiculite does it aids drainage.Both materials are sterile and relatively p h neutral,I use[/FONT] a 50:50 mixof Vermiculite and vermi-compost and find it an ideal mix for rooting cuttings.
Costs of Vermiculite vary enormously and if you use it in any quantity you can obtain 100 litre bags from diy stores it is used as loft insulation for about £7.00 a bag much cheaper than garden centers.

 

I got my vermiculite off ebay a couple of years ago. Great seller even lets you choose the ratios of the granularity.

 

Well, it's all so obvious, now :rotfl:

 

Basically, they are used for the same reason. It`s just that one, Perlite, is manmade ie polystyrene, and the other, Perlite, is natural ie Silica.:gnthb:

 

Er, you say both are manmade?

 

Newby David is confused Vermiculite and Perlite are both natural materials, Polystyrene is something completely different and is a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry. Polystyrene is one of the most widely used kinds of Plastic.

 

Dont quite do the same thing.

here'sthe link

http://www.william-sinclair.co.uk/gardening/products/compost_additives

and here's the wordy bit:

"Perlite
A naturally occurring non-toxic, natural volcanic rock which is heated to a high temperature to produce a lightweight micro-porous structure.


Recommended Uses: Rooting cuttings and pricking out.
Benefits: Absorbs and hold vast quantities of air and moisture to prevent compaction. Improves aeration and drainage., Stable and long lasting.




Vermiculite
A naturally occurring, non-toxic, soft mica material which is heated to a high temperature to produce a lightweight, sterile, laminated structure.


Recommended Uses: Seed sowing and pricking out.
Benefits: Absorbs nutrients which prevents them from being washed out and then releases them to the plant roots. Holds moisture near to roots. Insulates against fluctuations in surface temperature when used as a seed covering