Calculator
Vermiculite mixing calculator
Calculate how much vermiculite and potting soil you need for a mix with your chosen vermiculite share.
Choose the total amount of mix and the share of vermiculite to see how much of each to combine.
How to use the result
Typical shares: 10–20% to help containers hold moisture, 20–30% for seed-starting mixes.
Vermiculite retains water and nutrients while keeping the mix loose — useful for seedlings and moisture-loving plants.
For plants that need fast drainage, combine it with perlite or choose perlite instead.