## Common ground
All options are materials used to support plant growth, either as a substrate, soil substitute, or nutrient carrier in agriculture or horticulture.
## Options at a glance
**0602.90 – Mushroom substrates**
- **Defining trait:** Specifically designed for commercial mushroom cultivation (e.g., on logs or composted materials).
- **Typical examples:** Straw-based composts, sawdust mixes for oyster mushrooms.
- **Best fit when:** The medium is used to grow mushrooms commercially, not general plants.
**1404.90 – Vegetable-growing mix**
- **Defining trait:** A blend of organic, renewable materials (e.g., coco coir, perlite) for growing vegetables.
- **Typical examples:** Coco peat + vermiculite blends for tomato or lettuce cultivation.
- **Best fit when:** Used in vegetable farming with organic, sustainable components.
**2302.40 – Oat and corn-based medium**
- **Defining trait:** Made primarily from processed cereal by-products (oats, corn).
- **Typical examples:** Fermented oat bran mixtures for seedlings or small-scale growing.
- **Best fit when:** The product is based on agricultural waste like oat bran or corn.
**3824.99 – Mineral-based potting soil mix**
- **Defining trait:** Contains earth, sand, clay (Chapter 25 materials), possibly with added fertilizers.
- **Typical examples:** Soil blends with added minerals for container gardening.
- **Best fit when:** The medium is mineral-rich and includes inorganic components.
**6806.10 – Rock wool bulk**
- **Defining trait:** Synthetic, inorganic material made from molten rock (rock wool) used in hydroponics.
- **Typical examples:** Rock wool cubes for seed starting in greenhouses.
- **Best fit when:** Used in commercial hydroponic or greenhouse systems.
**6806.90 – Vermiculite-based medium**
- **Defining trait:** Made from expanded natural vermiculite, used for moisture retention and aeration.
- **Typical examples:** Seed-starting mixes or potting soils with exfoliated vermiculite.
- **Best fit when:** The product is primarily vermiculite-based, especially for seed germination.
## Key differences
| Option | Base Material | Organic/Inorganic | Primary Use | Fertilizer Inclusion |
|-------|----------------|--------------------|--------------|------------------------|
| 0602.90 | Organic (straw, compost) | Organic | Mushroom farming | No |
| 1404.90 | Organic (coco, perlite) | Organic | Vegetable growing | Rarely |
| 2302.40 | Organic (oat, corn) | Organic | General plant growth | No |
| 3824.99 | Inorganic (clay, sand) | Inorganic | Potting soil | Yes (common) |
| 6806.10 | Inorganic (rock wool) | Inorganic | Hydroponics | No |
| 6806.90 | Inorganic (vermiculite) | Inorganic | Seed/seedling start | No |
## How to choose
- Is it used for growing mushrooms? → 0602.90
- Does it contain coco, perlite, or similar organic materials? → 1404.90
- Is it made mainly from oat bran or corn? → 2302.40
- Does it include sand, clay, or earth? → 3824.99
- Is it rock wool used in greenhouses/hydroponics? → 6806.10
- Is it primarily exfoliated or expanded vermiculite? → 6806.90
## Overlaps & pitfalls
- **Overlaps:** A mix of coco coir and vermiculite could fit both 1404.90 and 6806.90; a mineral-based medium with fertilizers may overlap 3824.99 and others.
- **Pitfall:** "Growing medium" is broad—prioritize the **main material** (e.g., organic vs. inorganic) or **primary use** (mushrooms vs. vegetables).
- If unclear, choose based on the product’s **defining component** or **main application**