When to Introduce Fresh Air (FAE)

When to Introduce Fresh Air (FAE)

Fresh air exchange (FAE) is what triggers your grow to start fruiting. Timing it correctly makes a big difference in how your mushrooms develop.

When to Start

Introduce fresh air once your substrate is:

  • Fully colonized
  • White across the surface
  • Starting to show early pinning (small mushroom formations)

Do not introduce fresh air too early.

How to Do It

For CVG (dung-loving species):
Cut a slit just above the substrate about the width of the filter patch.

For Masters Mix (wood-loving species):
Cut a slit directly into the side of the substrate where you want mushrooms to grow.

What to Expect

  • Pins will begin forming near areas with fresh air
  • Growth will accelerate once conditions are right
  • Mushrooms will form where humidity and airflow are balanced

Important Notes

  • Fresh air and humidity must stay balanced
  • Too much airflow can dry out your grow
  • Too little airflow can stall development
  • Keep conditions stable after introducing FAE

Common Mistakes

  • Introducing fresh air too early
  • Cutting openings that are too large
  • Letting the substrate dry out
  • Not providing enough airflow
  • Constantly changing conditions