A houseplant soil mix recipe generator creates custom potting mix formulas with exact ingredient ratios for 100+ plant species. See a visual ratio bar showing peat, perlite, bark, and charcoal proportions, plus volume calculations for your pot size.
Soil Mix Ratio
How Much to Buy
Select a plant to generate the soil mix recipe.
How to Use the Soil Mix Recipe Generator
Commercial potting mixes are designed for a generic "average houseplant" — but your specific plants have very different needs. A succulent drowns in moisture-retaining mix. A fern wilts in fast-draining cactus mix. This generator gives you a plant-specific recipe using common ingredients available at any garden center.
Key Soil Ingredients Explained
Peat moss or coco coir — the base material. Retains moisture and nutrients. Peat has a slightly acidic pH (4.5-5.5), ideal for tropical plants. Coco coir is more neutral and sustainable. Most mixes use 30-60% of this base.
Perlite — expanded volcanic glass. Improves drainage and prevents soil compaction. The white "styrofoam-like" pieces you see in commercial mix. More perlite = faster drainage. Succulents need 40-50% perlite; moisture-loving tropicals need 20-25%.
Orchid bark — pine bark chips that create air pockets. Especially important for aroids (monsteras, philodendrons, pothos) that grow as epiphytes in nature. Breaks down over 1-2 years, enriching the mix as it does.
Horticultural charcoal — absorbs toxins and improves drainage. Most valuable in terrariums or pots without drainage holes. Optional for standard containers with good drainage.
Calculating Volume
Enter your pot's diameter and depth to get precise volumes for each ingredient. The calculator uses a cylinder formula (π × r² × h) and accounts for typical soil settling (~80% fill). This tells you exactly how many quarts or liters of each ingredient to buy — no more buying too much or running short midway through a repot.
For a detailed walkthrough, see our guide: Indoor Plant Soil Guide.
FAQ
Is this tool free?
Yes, completely free with no signup required.
Is my data safe?
Yes, all calculations run locally in your browser. No data is sent to any server.
What is perlite and why add it to soil?
Perlite is a lightweight volcanic glass that improves drainage and aeration in potting mixes. It prevents soil compaction and allows excess water to drain freely while keeping the mix loose enough for root growth. Most tropical houseplants benefit from 20-30% perlite in their soil mix.
What is the difference between peat moss and coco coir?
Both are moisture-retaining base materials but differ in sustainability. Peat moss is mined from peat bogs (a slow-renewable resource) while coco coir is a coconut processing byproduct. Coco coir has a more neutral pH and wets more easily when dry. Either works in houseplant mixes — coco coir is the more sustainable choice.
What does orchid bark do in a soil mix?
Orchid bark (pine bark chips) adds air pockets to the mix, mimicking the loose, chunky substrate that epiphytic plants grow in naturally. It breaks down slowly (lasting 1-2 years) and improves drainage and aeration. Essential for aroids, orchids, and any plant prone to root rot.
Do I need activated charcoal in my soil mix?
Activated charcoal (horticultural charcoal) helps absorb toxins and neutralize odors in soil. It's most useful in terrariums, pots without drainage holes, or closed systems where water can't flush through. For pots with proper drainage, it's optional — good drainage eliminates most of what charcoal would otherwise address.
How do I calculate how much soil I need?
The tool calculates total volume for your pot size and breaks it down by ingredient. For a round pot, volume = π × radius² × height. A 6-inch pot filled to 5 inches deep holds about 1.1 liters / 0.3 gallons. A 10-inch pot filled 8 inches deep holds about 5.2 liters / 1.4 gallons.