Advanced Soil Mix Calculator
Create professional grade substrates. Use our master recipes or design your own in the Lab.
Why DIY Your Soil?
Bagged potting soil is often designed for one thing: shelf life. It's usually extremely dense peat moss that holds water for weeks—a death sentence for houseplants like Monsteras and Alocasias that need oxygen at their roots.
By mixing your own substrates, you control the Drainage (how fast water leaves) and Aeration (how much oxygen stays). This is the secret to nursery-quality growth.
Why This Tool?
Smart Presets
Instant, expert-approved recipes for Aroids, Succulents, Ferns, and Seedlings.
Custom Lab Mode
Design your own substrate. Adjust percentages with precision sliders.
Bag Estimator
Tells you exactly how many bags of Bark or Perlite to buy.
Visual Stack
Beautiful stacked bar chart shows your mix composition at a glance.
Unit Converter
Switch seamlessly between Liters and Gallons for any batch size.
Printable Recipes
Download or print your custom mix plan to take to the garden center.
How to Use the Soil Mix Calculator
- Choose Mode: Select Presets for quick, proven mixes or Custom Lab to experiment.
- Set Volume: Enter your target batch size (e.g., "5 Gallons" for a large repotting session).
- Select Recipe: Click 'Aroid', 'Succulent', or 'Fern'. Or use sliders in Lab mode.
- Check Ingredients: The tool calculates exact volumes for each component (Bark, Soil, Perlite).
- Buy & Mix: Use the "Bag Estimator" to buy the right amount, then mix in a tub!
Real-World Example
You are repotting a large Monstera Deliciosa. You need about 10 Gallons of soil. You select the "Chunky Aroid Mix" preset.
The Ingredient Glossary
| Ingredient | Role | Best For |
|---|---|---|
| Orchid Bark | Creates large air pockets. Prevents compaction. | Aroids (Monstera, Philo), Orchids, Hoyas. |
| Perlite | Improves drainage. Lightweight aeration. | Literally every indoor plant. |
| Coco Coir | Water retention base. Sustainable. | Ferns, Begonias, Calatheas (Use instead of Peat). |
| Charcoal | Filters toxins. Antibacterial. Sweetens soil. | Terrariums, Cache pots, Propagations. |
| Worm Castings | Gentle organic fertilizer. Microbes. | Mix into everything for nutrients. |
Troubleshooting Your Soil
Soil Stays Wet for 2+ Weeks
Your mix is too dense. Roots will rot from lack of oxygen.
Water Runs Straight Through
Too hydrophobic. The roots aren't getting a drink before the water vanishes.
White Mold on Surface
Saprophytic fungus feeding on decaying organic matter. Harmful if excessive.
Soil has Hard "Crust"
Compaction or mineral buildup from tap water.
Frequently Asked Questions
Why use chunky soil for indoor plants?
Most tropical houseplants are epiphytes that grow on trees, not in dense ground dirt. Chunky soil with bark and perlite mimics this environment, allowing oxygen to reach the roots. Dense soil suffocates roots, leading to rot.
What does Perlite do?
Perlite is expanded volcanic glass. It adds 'porosity' to the mix, creating tiny air tunnels that allow water to drain quickly and oxygen to flow. It never decomposes.
Can I reuse old potting soil?
It's risky. Old soil can harbor pests (gnat eggs), diseases (fungal spores), and has depleted nutrients. If you must, sterilize it in the oven (180°F for 30 mins) and mix in fresh worm castings.
What is the difference between Coco Coir and Peat Moss?
Both hold water. Peat Moss is acidic and non-renewable (harvested from bogs). Coco Coir is pH neutral and sustainable (made from coconut husks). We recommend Coir for most houseplants.
Do I need Worm Castings?
Technically optional, but highly recommended. They act as a natural, gentle fertilizer that won't burn roots. They also add beneficial microbes to the soil ecosystem.
How do I store leftist mix?
Store in an airtight container (like a plastic bin or bucket with lid). Keep it dry. If it gets wet, fungus gnats may breed in the bag.
My soil dries too fast. What should I add?
Add more absorbent materials like Coco Coir, Peat Moss, or Vermiculite. Reduce the amount of Bark and Perlite.
My soil stays wet too long. What should I add?
This is dangerous! Add more Orchid Bark and coarse Perlite immediately to increase drainage and airflow.
What is Horticultural Charcoal used for?
It absorbs impurities and toxins in the soil, keeps the mix 'sweet' (preventing odors), and aids in drainage. Essential for terrariums or pots without drainage holes.
Is 'Cactus Soil' just sand?
No! Pure sand compacts into concrete. A good cactus mix is mostly porous grit (pumice, lava rock, perlite) with some coarse sand and a little organic soil.
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