Liquid culture, and storing leftover syringes
Why liquid culture beats spores for speed, and what to do with the half-full syringe.
A spore syringe holds spores that still have to germinate. A liquid culture syringe holds mycelium that's already growing. In practice that difference buys you a week or two of colonisation time, and a lower chance of a jar that never takes off.
Storing what is left
Most syringes hold more than one grow's worth. Cap the needle, wipe the barrel with 70% isopropyl and keep it in the fridge — not the freezer, which ruptures the cells. Spore syringes keep for many months this way; liquid culture is best used within a couple of months while the mycelium is still vigorous.
Let a refrigerated syringe come back to room temperature for several hours before you use it. Injecting cold culture into warm substrate stresses it.
Expanding a culture
You can grow a small amount of liquid culture into much more using sterilised sugar water — typically 4% light malt extract or honey — in a jar with a self-healing injection port. Sterilise, cool completely, inject a few millilitres of culture, and keep it at room temperature, swirling every day or two. In one to two weeks the jar is cloudy with mycelium and ready to inoculate from.
Sterile technique matters more here than anywhere else in the process: a contaminated culture jar quietly contaminates every grow you use it in. If it smells sour or shows any colour that is not white, throw it out.