For all you first-time growers, we put this glossary together to help you understand the words and slang used in the mushroom growing world. Enjoy!
Abort: A mushroom that stops growing and never reaches maturity. Aborts can be of varying sizes and are a common occurrence. See Pinning.
Agar: A gel made from seaweed, mixed with nutrients and poured into petri dishes to grow and isolate mycelium. See our guide on how to use agar plates.
Agar Slant: A test tube of agar set at an angle, used for long-term culture storage.
Birthing: Removing a cake from its jar after the mycelium reaches 100% colonization.
Brown Rice Flour (BRF): Ground brown rice; the main nutrient in PF Tek jars.
Bulk Substrate: Sometimes referred to as "bulk sub" or "casing mix." A mixture of soil-like materials that absorb water and are mixed with grain spawn to initiate fruiting. Usually contains vermiculite and coco coir, and may contain manures or peat moss. Shop bulk substrate.
Cake: Usually a reference to a PF cake, made from brown rice flour, vermiculite, and water. Spores or culture are injected into the cake and the mycelium grows out through it. See PF Tek.
Cap: The top part of a mushroom, often conical or saucer-shaped. See mushroom anatomy.
Casing Layer: A layer of water-retentive material applied on top of colonized substrate to encourage fruiting. See our guide to casing soil.
Casing Mix: See Bulk Substrate.
Clean Room: A room with a low dust and contaminant count, used for sterile work.
Cobweb Mold: Common name for Dactylium, a mold commonly seen on casing soil or parasitizing mushrooms. It is cobweb-like in appearance, first shows up in small scattered patches, then quickly runs over the casing surface and overwhelms mushrooms in its path.
Coir: A coarse fiber from the outer husk of a coconut. Absorbs water and resists contamination.
Cold Shock: Lowering the temperature of a PF cake or cased bed to promote pinning.
Colonize: The process of mycelium growing through and consuming a substrate. See how long colonization takes.
Colony: A distinct mass of microorganisms, usually growing in or on a solid medium.
Compost: Decayed organic matter or manure.
Contam, Contaminant: Undesirable mold, yeast, or bacteria. See our contamination identification playbook.
Desiccant: A water-absorbing material, usually silica gel or activated alumina, used to dry mushrooms. See how to dry mushrooms.
Dextrose: A simple sugar used in liquid culture and agar recipes.
Distilled Water: Water purified by boiling it into steam and condensing it back to liquid, leaving no dissolved impurities.
Double-End Casing: Setting a cake on a jar lid of vermiculite and then putting a few tablespoons of vermiculite on top, then wetting it down.
Dunking: Soaking a cake or substrate in water to rehydrate it between flushes. See should you dunk a bulk grow?
FAE (Fresh Air Exchange): Replacing CO2-rich air in a grow chamber with fresh air, a key fruiting trigger.
Flow Hood: A laminar flow hood blows HEPA-filtered air across a work surface for sterile work. See laminar flow hood vs FFU.
Flush: A wave of mushrooms that form and mature over a short period. Most substrates produce several flushes.
Foil Covers: Squares of foil wrapped over the tops of jars during sterilization.
Fruitbody, Fruiting Body: The mushroom itself; the part that grows above the substrate and produces spores. See what triggers fruiting.
Gills: The thin plates on the underside of the cap where spores are produced.
Glovebox / Still Air Box: An enclosed box used to create a still, clean working area for inoculating jars or bags.
Grain Spawn: Sterilized grain colonized by mycelium, used to inoculate bulk substrate. See our complete guide to grain spawn.
Green Mold: See Trich.
Grow Chamber: See Terrarium and Monotub.
Gypsum: Calcium sulfate, an additive used to loosen substrate and add calcium.
H2O2: Hydrogen peroxide, used for cleaning and sanitation.
Harvesting: Picking mushrooms when they are mature, for many species just as or before the veil breaks. See our harvest timing guide by species.
HEPA Filter: High-Efficiency Particulate Air filter, rated to capture at least 99.97% of particles 0.3 microns in size.
Hydrated Lime: An additive used to buffer the pH of casing mixes.
Hygrometer: An instrument for measuring humidity.
Inoculating: Introducing spores, liquid culture, or colonized material into a sterile substrate.
Incubation: Keeping an inoculated substrate at a steady, warm temperature to promote colonization.
Isopropyl Alcohol: Rubbing alcohol. Used to sanitize surfaces, tools, and hands.
Jars: The containers in which substrate is packed and sterilized. See half-pint jars vs grain jars.
Lime: Calcium carbonate (pickling or garden lime), used to raise pH.
Liquid Culture: Live mycelium growing in a sterile sugar-water solution, used as inoculant. See liquid culture vs spore syringes.
Magic Mushroom: Any of a number of fungi containing the compounds psilocybin and/or psilocin, such as Psilocybe cubensis.
Misting: Spraying water to maintain humidity and surface moisture.
Monotub: A plastic tub modified for fruiting bulk substrate. See our step-by-step monotub guide.
Mushroom: The fleshy fruiting body of a fungus, in which spores are produced and from which they are distributed.
Mycelium: The vegetative body of a fungus, a network of thread-like hyphae. Mycelium networks can be huge; some of the largest living organisms on Earth are single mycelial networks.
Mycophile: A person who loves mushrooms.
Organic: A product derived from a living thing and processed without synthetic fertilizers, pesticides, or drugs.
Overlay: A condition where mycelium completely covers the casing or substrate surface and forms a dense mat instead of pinning. See what overlay is and how to fix it.
Oyster Shell: Ground or crushed shell used as a calcium additive in substrates.
Pasteurization: Heating bulk materials to roughly 140–170°F to reduce, but not eliminate, competing organisms. See sterilize vs pasteurize.
Perlite: A lightweight, porous volcanic glass. When damp, it releases moisture into the air, which is why it's used to humidify fruiting chambers.
Phototropic: Growing toward light.
Pin, Primordia, Pinning: The first recognizable mass of hyphae that develops into a mushroom. See why your monotub isn't pinning.
Polyfil: Polyester fiber used as a breathable filter in jar lids.
Pressure Cooker: Used to sterilize substrates and grain at 15 PSI. Shop autoclaves and pressure cookers.
Psilocybin, Psilocin: Hallucinogenic compounds found in some mushrooms.
Rhizomorphic: Describes rope-like, strand-forming mycelial growth, often a sign of a vigorous culture.
Rice Cake: See Cake.
RO Water: Water purified by reverse osmosis.
Rust: Forms on metal jar lids; generally harmless.
Rye: A popular grain for grain spawn. See Substrate.
Sanitizing: Killing contaminants on smooth surfaces, usually with an alcohol or chemical wipe.
Spawn: Fully colonized material, usually grain, used to inoculate bulk substrates. Shop colonized grain spawn.
Spawn Bag: A filter-patch bag used to sterilize and colonize grain. See everything to know about spawn bags.
Spores: What mushrooms have instead of seeds. Microscopic, and produced by the millions by each mushroom.
Spore Print: The pattern left when spores drop from a cap onto paper, foil, or glass. See how to harvest spores.
Spore Syringe: Spores suspended in sterile water in a syringe, used to inoculate substrate. See our spore syringe buying guide.
Stem / Stipe: The stalk of a mushroom.
Sterilize: To make free of all living microorganisms, usually with pressurized steam.
Strain: A genetic variety within a species. Each strain shares genetics but can differ in growth speed, yield, and appearance.
Straw: The stems of grain plants such as wheat after the grain has been removed; a common pasteurized substrate.
Stroma: A dense, cushion-like growth of mycelium on the surface of compost or casing, indicating the culture is still in vegetative growth.
Substrate: Any material mushrooms can grow on, from grain to sawdust to manure. See what mushroom substrates are.
Terrarium: An enclosure for fruiting mushrooms indoors.
Tek: Grower shorthand for "technique," often prefaced with the method name, e.g. PF Tek.
Trich: Trichoderma, a common green mold contaminant.
Tyvek: A breathable, moisture-resistant material made of spun-bonded olefin fibers, used as a filter.
Veil: Tissue connecting the cap edge to the stem on developing mushrooms. As the cap expands, the veil tears, often leaving a ring on the stem.
Vermiculite: A highly absorbent mineral made from expanded mica. Used in PF Tek jars to hold water and as a casing material.
Water: Use clean water throughout.
Wheat: See Substrate.
White Fuzz: Normal fuzzy mycelial growth on mushrooms or casing, often from high humidity or CO2; not to be confused with mold.
Worm Castings: An organic additive used in some substrates.