Description
🌸 Knudson C Medium — the original asymbiotic orchid germination medium, formulated by Lewis Knudson at Cornell University in 1946. Still the standard for most terrestrial orchid genera.
| 📦 Format | Powder → 1 L | 🔬 Grade | TC / Tissue Culture |
| ⚗️ Working pH | 5.2–5.4 | 🌡️ Storage | 2–8 °C, sealed |
💡 Why orchids need their own medium
Orchid seeds are dust-like — essentially an embryo with no endosperm and almost no nutrient reserve. In nature they germinate only in symbiosis with mycorrhizal fungi. Knudson’s medium replaces the fungus by providing sucrose as the carbon source, calcium, and simple mineral salts at low ionic strength matched to orchid root zone chemistry.
🌸 Application by orchid group
| Use | Concentration | Notes |
|---|---|---|
| Phalaenopsis (PLBs → shoots) | Knudson C + 1 mg/L BAP | Standard Stage II |
| Dendrobium seed germination | Knudson C, 10 g/L sucrose | pH 5.2 critical |
| Cattleya & allied genera | Knudson C + 100 mL/L coconut water | Historical protocol |
| Terrestrial orchid germination | Knudson C, minimal supplements | Species-specific |
💡 Orchid seeds have near-zero germination on MS — the high salt concentration is inhibitory. Always use Knudson C or Vacin & Went for seeds.
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