Quick Tip: Keep Your Spawn Bags Moist with a Simple Hygrometer
Maintaining the right moisture level in your spawn bags is key to healthy mycelial growth. A cheap, reliable way to monitor moisture is to use a plastic water‑bottle hygrometer.
- Grab a clear plastic bottle (e.g., a 1 L water bottle) and a few strips of damp cloth or cotton.
- Squeeze the bottle gently so the water inside stays at the bottom. The bottle should be airtight so the humidity inside the bag influences the water level.
- Place the bottle in a small, sealed container (e.g., a zip‑lock bag) that will hold the spawn bag’s headspace.
- Check the water level daily:
- If the water rises, the air inside the bag is too dry—add a small spray of sterile water to the surface.
- If the water level drops, the bag is too wet—let it dry out a bit before the next inoculation.
Why this works
The water in the bottle acts as a humidity gauge: it will rise as the air around it becomes drier and fall when the air is moist. Because the bottle is sealed, it reflects the actual conditions your mycelium experiences, not just surface moisture.
Tip for accuracy – keep the bottle in a consistent location (e.g., next to the spawn bag, not under direct light) and avoid touching the water with your hand, which can add moisture.
Using a DIY hygrometer is inexpensive, non‑intrusive, and gives you a quick visual cue so you can keep your spawn bags in optimal condition.