Organic Rye Berries | 1 kg Bulk Grain Substrate

Rye has been the textbook grain spawn for cubensis cultivation since the very first mycology manuals. The kernels absorb water at a controlled rate, the husks survive pressure sterilisation without splitting, and the nutrient profile suits a wide spectrum of fungi. Our 1 kg bags come from certified organic European farmland, screened for foreign material and ready for the spawn jar.

Product specifications

• Available sizes: 1 kg bag
• Species: Secale cereale — rye grain berries
• Kernels per kg: approximately 3 000
• Origin: certified organic European farmland, Non-GMO
• Use: grain spawn substrate after hydration and pressure sterilisation

Why rye remains the classic choice

• Reliable hydration — rye kernels reach the ideal "field capacity" moisture content (around 45%) without splitting
• Tough husk — survives 121 °C / 15 PSI sterilisation intact and resists contamination during shake-out
• Universal compatibility — supports virtually every common cultivated mushroom species
• Cost-effective — widely available, low-cost grain that scales from hobby to commercial volumes

Which mushrooms grow on rye grain spawn

• Psilocybe cubensis — all strains (the classic pairing)
• Pleurotus ostreatus, Pleurotus eryngii — oyster mushrooms
• Hericium erinaceus — lion's mane
• Lentinula edodes — shiitake (with hardwood transfer)
• Stropharia rugosoannulata — wine cap

How to prepare rye grain spawn

1. Rinse — rinse the dry rye under clean water until run-off is clear
2. Soak — submerge in clean water for 12–24 hours
3. Simmer — drain and simmer for 15–20 minutes; kernels should be tender but firm, not split
4. Drain & dry — spread on a clean towel to surface-dry until kernels no longer feel wet
5. Jar & sterilise — load into autoclavable jars or bags with a 5.0 µm filter patch; pressure-sterilise at 121 °C / 15 PSI for 90–120 minutes
6. Cool — let the jars cool to 24–27 °C before inoculation
7. Inoculate — add 1–3 ml of liquid culture or spore syringe per jar through a self-healing injection port
8. Incubate — keep at 24–27 °C in the dark; shake gently when the first signs of colonisation appear

Rye vs. millet — which to choose

Rye and millet are both proven grain spawn substrates. Choose rye for the classic, well-documented workflow with a wider safety margin around moisture control. Choose millet for faster colonisation and 2.5× more inoculation points per kilogram. Many cultivators use both: rye for initial spawn, millet for grain-to-grain expansion.

Skip the prep work

If you'd rather buy a fully sterilised, ready-to-inoculate spawn bag, see our sterile grain spawn options: Sterile Millet Spawn Bag or Sterile Sorghum Spawn Bag .

Pair with a bulk substrate

Colonised rye spawn transfers cleanly into bulk substrates at a 1:2 to 1:5 ratio by weight: Sterile CVG Substrate Mix for cubensis-type species or Coco Bricks Substrate Base for DIY blends.

Storage

Store unopened bags in a cool, dry place, away from direct sunlight and rodents. Dry rye has a shelf life of 12+ months when kept dry.