Heirloom Growing Tips

Amycel Heirloom Growing Tips

(Spanish Click Here)

 The following is a collection of tips to assist the Heirloom grower in adapting the growing process to optimize mushroom production. These tips are not meant to be growing advice but are strictly anecdotal tips to assist you in finding the right conditions for your farm.

Heirloom is a highly prolific strain which can be used for either Portabellas or Crimini production. It is a unique strain and it requires slightly different growing conditions than other commonly cultivated varieties to achieve optimal production. If Heirloom is not handled properly, it can manifest a host of unique problems including (but not limited to):  weepers, foaming of the casing soil, and reduced second break.


Heirloom cannot be cross cac’ed with any other strain!

  • Moisture management is a key issue
  • Casing must be kept open and not sealed
  • Interface is critical and must be maintained

 Spawn Run:

  • Typically runs faster in the compost.  On the other hand, the spawn run must be complete. Some  growers believe that an immature spawn run can increase the incidence of  foaming.


  • Heirloom can be more sensitive to casing/compost moisture differentials.
  • Heirloom can grow more slowly in the casing layer, than the traditional browns      (2468), and growth may need to be managed differently.


  • Heirloom can be flushed hard.  The mycelium will stop fuzzing almost immediately and the casing will look black.  Light passes are given until the pins form unless there is active humidification in the room.  Water can be applied directly on top of thumb sized pins if environmental conditions  allow.
  • Care should be taken while pinning the room.  Wait until the pinset forms and then bring on the first break.

Between Flush Management:

  • Maintain the integrity of the interface between the compost and the casing by  whatever means is necessary


  • Excess watering after casing/flush may cause extreme weeping events.  It is recommended that careful attention is paid to casing soil water management.
  • Keep the casing soil open.  Fine peat can compact during irrigation.
  • Light ruffling can help keep the casing soil open and improve pinning.
  • Excess moisture is an ongoing theme when problems occur with Heirloom. Reducing casing moisture will correct almost all of the problems encountered during cropping.


  • Heirloom can lighten up on second break if the break is heavy.
  • Heirloom grows vigorously as the mushrooms develop.  Air temperature must be reduced to slow down the rate of tissue development.  Otherwise, stem discoloration and cap cracking may occur.
  • A  good evaporation gradient must be maintained.  The air needs to be fresh with low CO2  for evaporation but still humid.  It is a tedious balance until the grower finds what works best and to adjust when outside conditions change.


The foaming is a “weeper” from the mycelium instead of from a developed mushroom.  It is milky white to brown liquid and gives off a pungent odor.  Production will be low to non-existent in these areas.  If the areas are localized, the casing can be removed from these spots to avoid further spread.  Foaming is often reported by growers when they start growing Heirloom for Portabellas.  It generally goes away when adjustments are made.  All growers have concluded that the casing soil needs to go on drier and that they provide a good evaporation gradient from casing through cropping..

Purple Stems and Cracked Cap Margins:

The metabolic rate of Heirloom is extremely high especially as the mushrooms size into Portabellas.  The canopy is also very dense.  The stipes will elongate rapidly and can strip away the core tissue.  This will lead to a purple stem discoloration in some but not all mushrooms.  Stem blow out can occur as well.  The caps also expand vigorously and will separate at the margins.  In most cases it does not affect the cosmetic appearance of the Portabellas.

The best practice to minimize the occurrence of purple stems and cracked cap margins is to lower the air temperature as much as possible as the Ports begin to size especially during the first break. The air temperature should be below 60F and even into the mid 50’s.  Air movement should be increased to remove excess heat but not enough to scale the caps.  Proper humidity should be maintained so the cap tissue does not become brittle and increase the severity of cracking.  Aggressive cooling is not as critical on later breaks and care should be taken not to lower compost temperatures to the point that the crop is slow coming into and finishing third break.