Potting Mix Blend Ratio
Calculator

It's the proportion by volume of each ingredient in the blend, such as 2 parts peat moss or coco coir, 1 part perlite, and 1 part compost, so the calculator scales these ratios up to the total volume of mix you need to produce.

Succulents and cacti need a fast-draining, gritty mix with more perlite or sand and less water-retentive material, while moisture-loving plants like ferns need a mix with more peat or coir to hold water longer, so the ideal ratio shifts based on the plant's native growing conditions.

Perlite creates air pockets in the mix, improving drainage and preventing compaction that would otherwise suffocate roots; skipping it in a mix intended to have it usually results in soil that stays too wet and compacts over time, increasing root rot risk.

Potting mix ingredients vary enormously in density (perlite is very light, compost is heavier), so mixing by weight would throw off the intended ratio; volume-based measuring with a consistent scoop or container keeps the actual mix proportions accurate to the recipe.

Often yes with adjustment: vermiculite can sometimes replace perlite though it retains more moisture, and coco coir can replace peat moss as a more sustainable option with similar water-holding properties, but substitutions should account for how the replacement's drainage and moisture behavior differs from the original.