Potting Soil Mix Ratio Calculator
Calculate the exact quantities of peat moss, perlite, vermiculite, and compost needed for your custom potting soil mix. Perfect for seed starting, general houseplants, and succulents.
Custom Potting Mix Details
Enter your desired total volume and ingredient ratios to calculate exact amounts
The total amount of finished potting soil you need for your pots or seed trays.
The primary moisture-retaining base of your mix.
Improves drainage and prevents soil compaction.
Acts like a sponge to hold water and nutrients. Use 0 for succulents.
Provides organic matter and slow-release nutrients. Use 0 for seed starting.
Ingredient Quantities
Exact volumes for your custom potting soil blend
Enter your desired volume and mix ratios above, then click Calculate Potting Mix to see your exact ingredient amounts.
Common Potting Soil Recipes
Use these standard ratios as a starting point for your custom blends. Ratios are expressed as Parts (Peat : Perlite : Vermiculite : Compost).
| Application | Mix Ratio (P:P:V:C) | Characteristics & Use Case |
|---|---|---|
| General Purpose | 1 : 1 : 1 : 1 | Balanced moisture, drainage, and nutrients. Ideal for most houseplants. |
| Seed Starting | 2 : 1 : 1 : 0 | Fine texture, sterile, and moisture-retentive. No compost to prevent damping off. |
| Moisture Lovers | 2 : 1 : 2 : 1 | High water retention for ferns, calatheas, and tropical plants. |
| Succulents & Cacti | 1 : 3 : 0 : 1 | Extremely fast-draining and gritty. Prevents root rot in drought-tolerant plants. |
| Outdoor Containers | 1 : 1 : 0 : 2 | Heavier mix that withstands wind and dries out slower in full sun. |
Potting Soil Mix FAQ
Everything you need to know about creating the perfect DIY potting soil for your plants.
A classic and highly effective ratio for most general houseplants is 1:1:1:1 (one part peat moss or coco coir, one part perlite, one part vermiculite, and one part compost or worm castings). This provides a perfect balance of moisture retention, aeration, drainage, and essential nutrients. For a simpler mix, 1:1:1 (Peat:Perlite:Compost) also works exceptionally well.
Perlite is a lightweight, porous volcanic glass that improves drainage and aeration, allowing excess water to flow through quickly. Vermiculite is a spongy mica mineral that acts like a reservoir, holding onto water and nutrients to keep the soil moist. Use perlite for plants that like to dry out (like succulents) and vermiculite for plants that prefer consistently moist soil (like ferns).
It is highly recommended not to use straight garden soil in containers. Garden soil is too dense, compacts easily when confined to a pot, and restricts root growth and oxygen flow. It may also contain weed seeds, pests, and soil-borne diseases. Potting mix is specifically engineered to be light, well-draining, and sterile, providing the ideal environment for container roots to breathe and thrive.
Both are excellent, sustainable bases for potting mixes, but they have slight differences. Peat moss is slightly acidic (pH 3.5–4.5) and holds water well, but it can be hard to rewet once completely dry. Coco coir has a more neutral pH, wets much more easily, and is considered more environmentally friendly as it is a byproduct of the coconut industry. Either works perfectly as the ‘base’ part of your potting mix ratio.
Succulents and cacti require extremely fast-draining soil to prevent root rot. A great DIY ratio is 1 part peat moss (or coco coir), 3 parts perlite (or coarse horticultural sand), and 1 part compost. Avoid using vermiculite in succulent mixes, as its high moisture-retention properties can keep the soil too wet for these drought-tolerant plants.