Vermiculite and Perlite

Question 1

Vermiculite

What is it?

Answer 1

Aluminium-iron-magnesium silicate.

Question 2

Vermiculite

Porosity and nutrient adsorption

Answer 2

High initial porosity

High CEC

Question 3

Vermiculite

Advantages

Answer 3

Sterile - high temps used in manufacturing.
As addition (10% to 20% of growing media) it improves aeration and has water holding capabilities.
Decays and disappears in soil over time

Question 4

Perlite

What is it?

Answer 4

Silicate from volcanic origin.

Question 5

Perlite

Manufacture

Answer 5

Rock is crushed and heated to form lightweight aggregates.

Question 6

Perlite advantages and disadvantages

Answer 6

Improves aeration
No nutrient value
Sterile.
Useful as addition in propagation (usually 10% to 20% but can be up to 50%)
Granules are porous, rough surface holds water.
Used in composts to improve aeration and drainage.
Expensive.
Dusty, care should be taken when handling.

Question 7

Vermiculite

pH

Answer 7

Different vermiculite have different pHs, slightly acidic formula is preferred in horticulture.

Question 8

Vermiculite

Disadvantages

Answer 8

Dusty, care needed when handling.

Not stable - get soggy when wet.