A grain bag can only tell you whether a culture was clean after it has eaten three weeks of your time. An agar plate tells you in three days. That is why every serious grower, hobby or commercial, keeps plates: they are the cheapest, fastest way to see what is in a syringe, to pick the strongest part of a culture, to rescue a contaminated one and to keep strains alive between grows. With pre-poured plates you skip the pressure cooking and pouring and start at the interesting part.

What you need

• Pre-poured plates: high-nutrition for expanding, low-nutrition for isolating and testing.
• A still air box: a clear tub with two arm holes. SAB guide.
• A scalpel or a craft knife with snap-off blades, and a lighter or small torch.
• 70% isopropyl alcohol in a spray bottle, paper towel, nitrile gloves.
• Cling film or micropore tape to seal plates, and a marker.

Your first transfer: liquid culture to agar

1. Set up

   Spray the inside of the still air box and everything going in it with alcohol: plates in their sleeves, syringe, scalpel, lighter, gloves. Let it settle for a minute so the air is still.

2. Open a plate

   Lift the lid just enough to get the needle in; never put the lid down on the bench. Keep hands low and slow.

3. Drop

   Flame the needle, cool it, and put two or three small drops of liquid culture on a low-nutrition plate. Lid on, seal with cling film around the edge.

4. Label

   Species, source, date. Every plate, every time.

5. Wait

   Room temperature, out of light. Growth shows in two to four days. Watch it daily.

Reading the plate

Good mycelium

White, even, advancing in a clean front. Thick rope-like strands (rhizomorphic) are a sign of vigour; fluffy cotton (tomentose) is usually fine but slower.

Bacteria

Shiny, wet, slimy patches, often cream, yellow or pink, sometimes with a sour smell. They show in a day or two, usually around where the drops landed.

Mould

Any colour that is not white: green, blue-green, grey, black, orange. Fuzzy, fast, and it will throw spores across the plate within days.

Yeast

Small, round, glossy colonies that look like dots of paint.

Isolating: cutting your way to clean

If the plate shows mycelium and a contaminant, you can still win. Wait until the mycelium has grown well away from the problem, then, in the still air box, flame your scalpel, cool it, and cut a small square (5mm) of agar from the far edge of the clean mycelium, as far from any contaminant as the plate allows. Lift it onto a fresh plate face down, seal, label. Repeat until a plate grows out with nothing but white. Two or three transfers usually do it. This is the single most valuable skill in home mycology.

Expanding: agar to grain

Once a plate is clean and vigorous, move a wedge to a high-nutrition plate to build stock, and from there to a sterilised grain bag: in the still air box, open the top of the grain bag just below the seal, drop in two or three wedges from the leading edge of the colony, fold and clip the bag. A wedge of strong agar colonises grain faster than a syringe does.

Habits that keep plates clean

• Flame and cool between every cut. A hot blade kills the culture; an unflamed one carries the last plate's problems.
• Lids open for seconds, not minutes. Have everything in reach before you lift one.
• Transfer from the leading edge. The youngest mycelium at the outer front is the most vigorous and the least likely to carry a hitchhiker.
• Store plates upside down in the fridge. Condensation drips onto the lid, not the agar.
• Bin the doubtful ones. A plate you are unsure about is not worth the grain bag it could contaminate.

Written by the Aus Myco Kingdom crew. Everything here is general growing information for gourmet and medicinal species; your room, your climate and your culture will have the final say.