How do you choose which one to use?
For Drainage: Choose perlite
For Water Retention: Choose vermiculite
For planters, I suggest using a little of each as they have complimentary properties.
The ratio should be 25% of one or both of these total to potting soil. So that means ¾ of the volume of potting soil and the rest (¼ of the volume) can be any balance of perlite and/or vermiculite.
Perlite
- white granular particles
- a form of volcanic glass
- containing about 6% water
- neutral pH
- surface area of the particles are covered with little indents that hold nutrients and water
- clean, odourless, sterile and non-toxic
- will not rot or mold
- better for drainage than vermiculite
- lightweight substitute for sand
- can float to the top of potted plants due to its light weight
- holds 3-4 times it’s weight in water
Vermiculite
- silicate mineral resembling mica, the colour can vary
- retain moisture and plant nutrients
- mixes well with soil
- clean, sterile, odourless, non-toxic
- cheaper than perlite
- contains trace minerals
- retains water, air and nutrients
- not as durable as perlite
- can trap too much water causing soggy, mucky soil
