Calculate lime (calcium hydroxide) or gypsum amounts needed to raise substrate pH to optimal levels (6.5-7.5). Proper pH prevents contamination and promotes healthy mycelial growth.
Agar is a gel-like substance derived from seaweed, used as a solid medium for growing mushroom mycelium in sterile conditions. Combined with nutrients, it provides an ideal environment for tissue culture, spore germination, and mycelium isolation.
Different formulas serve specific purposes:
Your spawn rate determines how quickly your substrate will colonize:
Slower colonization (14-21 days), higher contamination risk, most economical
Optimal balance of speed (7-10 days), reliability, and cost-effectiveness
Fastest colonization (3-7 days), lowest contamination risk, premium approach
Different mushroom species have different colonization speeds and benefit from adjusted spawn ratios:
MEA (Malt Extract Agar) is the best choice for beginners. It's inexpensive, easy to prepare, and works well with most mushroom species. Use 20g malt extract + 20g agar per liter of water.
Yes! Use a still air box (SAB) - a clear plastic tote with arm holes. Work slowly and deliberately. Pour plates in front of an alcohol lamp for added sterility. Many successful cultivators start this way.
Sealed agar plates last 1-2 months refrigerated at 35-40°F. Store inverted (upside down) to prevent condensation from dripping on the agar surface. Parafilm edges for longer storage. Check for contamination before use.
Cloudiness usually means incomplete dissolution before sterilization. Always bring agar to a full boil and stir until completely clear before pressure cooking. Some nutrients naturally cause slight cloudiness - this is normal for PDA.
Yes! Agar powder from Asian markets or health food stores works perfectly. It's the same product as lab-grade agar but much cheaper. Just ensure it's pure agar without additives or flavoring.
Pour at 130-140°F (55-60°C). Too hot (above 150°F) can crack plastic petri dishes. Too cool (below 120°F) and agar starts solidifying, creating lumps. Use an infrared thermometer to check temperature.
500ml makes approximately 25 standard 100mm plates (20ml per plate), 33 plates at 90mm (15ml each), or 50 small 60mm plates (10ml each). Always make a few extra to account for spillage and practice.