Grow mushrooms the EZ way.

Best Pressure Cooker for Growing Mushrooms at Home

Best pressure cooker for mushroom cultivation, capacity

A pressure cooker is the most important item needed when you want to grow mushrooms at home. It is very important to provide a sterile or pasteurized substrate for the mycelium to colonise.

Without one you will increase the likelihood of contamination growing alongside you're mycelium and ruining your batch; ultimately wasting your time.

Pressure cookers are the most expensive investment you will have to make when moving into the world of mycology so its important to understand what you are paying for before making an investment.

Often, people will buy a pressure cooker only to outgrow it within 12 months, so in this article I am going to discuss a few different options for people who want to start growing mushrooms from spawn syringes.

Top Pressure Cookers for Mushroom Cultivators:

Pressure Canner Best for
Presto 01781 23-Quart Pressure Canner and Cooker. Committed Mycologists and people who are serious about mushroom cultivation.
Presto 16-Quart Aluminum Pressure Cooker Canner. Beginner Mycologists. Presto reputation, decent capacity, cheaper price. Perfect for a beginner.
Zavor EZLock 12.7 Quart. Safety Concerned Beginner Mycologists.
22L Hawkins Big Boy Gas Only. Global based Mycologists (people outside US) looking for a big unit.

TLDR: We have investigated a range of pressure cookers for mushroom cultivation in this page, the options listed above are the options which stand out most to us.

The breakdown is pretty detailed and highlights features we checked such as jar capacity, ease of use, available locations, etc.

There is a small, medium and large category which all contain around 2-3 pressure cookers inside so if you have the time checkout the full post for a full analysis.

Any links you click which go to amazon provide me with a small commission, thanks!

Top Choices Of Pressure Cooker For Mushroom Growing:

Large options (20-23 Quarts)

Best for: Committed Mycologists and people who are serious about mushroom cultivation.

Material: Aluminium.

Size: Large. 14.8 inches Height, 15.1 inches Diameter, 22 Litres

Weight: 5.6kg

Racks included: 1 (recommended to buy a second one here).

Hob Type: Electric, Gas, Smooth top, Induction.

Available Location: USA, UK (eBay only).

Full pressure time: 10 minutes.

Warranty: 12-year limited warranty.

Capacity

To create this table we double stacked the jars using a rack that was provided by the manufacturer and a second rack which can be purchased here. You can triple stack this system and probably add another 6 ½ pint jars too.

The presto only comes with one rack, so it is recommended to purchase extra racks to get the most out of this unit!

Capacity (US Measurement) Capacity (Metric Measurement)
Wide Mouth. Wide Mouth.
26 x US ½ pint Jars. 26 x 240ml jars.
16 x US 1 Pint Jars. 16 x 500ml jars.
Regular Mouth. Regular Mouth.
26 x US ½ pint Jars. 26 x 240ml jars.
16 x US 1 Pint Jars. 16 x 500ml jars.
4 Large Spawn Bags.

 

Most serious mushroom cultivators purchase a 23 Quart Presto as they are reliable, huge and hold a lot of substrate. 

This whopping pressure cooker should hold at least 20 half-pint jars meaning you can create a whole lot of spawn in one go. 

If space isn't an issue I would recommend this cooker. 

Here is a picture of me stacking 10-pint jars inside the pressure cooker.

The Presto 01781 23-Quart is 23 cm tall and 32cm in diameter. It has been manufactured using extra strong aluminum and weighs 5.6kg. 

This doesn't sound like a lot but once it is filled with gain jars and water it definitely becomes more difficult to handle; make sure you are prepared to lift and move it around the stove (while full) when you use it. 

I usually place the cooker on top of my stove, then fill it with contents to avoid heavy carrying, however, there are still instances where you may need to shift it on the stove. 

The Presto 01781 includes three main parts, these are: 

The Pressure Gauge can help you ensure that you are sterilizing your mushroom substrate over 15 psi. 

The Pressure Regulator, which is basically a small weight that prevents the pressure cooker from exceeding 15psi. Sometimes mycologists will place a few coins (quarters) on top of this to allow it to exceed and remain over 15psi for extended periods. Alongside this, the original pressure regulator does rattle a lot when you get up to the top temperatures. 

The Vent Pipe, this is a pressure release valve that will release pressure in excess of 15 pounds. The pressure regulator sits on top of the vent pipe.

This pressure cooker can not be used on an LP gas burner outside as the temperatures will reach over 12000 which can result in the canner from breaking down risking an explosion. 

The prices for Presto canners can vary a lot. Even on Amazon, you'll find different sellers selling the same model for very different prices. It's worth shopping around the cooker often goes on sale for a cheaper price so look out for it around the sale periods.

What we like:

  • It's huge and can produce lots of grain spawn in one sitting.
  • It is reasonably priced for the size of the unit.
  • This product reaches the correct pressure fast.
  • Superb warranty.
  • The pressure Gauge ensures you see that you have reached sterilization levels.

What we don't like:

  • This pressure cooker regulator can be very noisy if you don't get the temperatures perfect at 15psi. It will go over and rattle like mad basically.
  • This pressure cooker uses a manual pressure regulator which may be daunting for new users as they have to place the pressure regulator on a steam vent whilst cooking.
  • Only one rack, but you can get a second on here.

Best for: Safety conscious mushroom cultivators who want a large unit. 

Material: Aluminium.

Size: Large. 16.26 inches Tall, 15.39 Inches Diameter, 22 Litres

Weight: 8.2kg

Racks included: 2

Hob Type: Electric, Gas, Smooth top, Induction.

Available Location: USA, UK, and EU.

Full pressure time: 10 minutes.

Warranty: 1 year limited warranty.

Capacity

In a similar fashion to the presto unit we tested the capacity with a double stack. With the T-Fal pressure cooker unit they provide 2 racks in the box which is definitely a bonus.

Capacity (US Measurement)

Capacity (Metric Measurement)

Wide Mouth.

Wide Mouth.

26 x US ½ pint Jars.

26 x 240ml jars.

16 x US 1 Pint Jars.

16 x 500ml jars.

Regular Mouth.

Regular Mouth.

26 x US ½ pint Jars.

26 x 240ml jars.

16 x US 1 Pint Jars.

16 x 500ml jars.

4 Large Spawn Bags.

 

The T-Fal 22 Quart pressure cooker is another huge unit that can hold tons of grains spawn at one time.

The main difference with this model is that it is much more beginner friendly.

This is due to the fact you don’t have to place a pressure regulator over a valve whilst it is running. Instead, you turn a dial to set your pressure before you apply heat.

Alongside this, features such as the handle which has been placed in the center of the top of the unit, and large handles on the sides make it easier to handle when removing the lid, keeping your hands away from the metal.

The unit also will not open until you release the steam through the vent by turning the pressure valve.

This can prevent you from opening it too soon and getting burned by the hot steam (you should be leaving it to cool anyway after sterilizing mushroom jars but it is still a nice feature).

Overall, the product feels more robust than the presto and the lid is definitely heavier (as it contains more components).

Once you get used to using the pressure cooker it is relatively quieter than other units with no rattling of weights.

The steam can make a hissing noise but once you get used to using it on your hob, you will know where to place it and what temperatures to use to keep consistent quiet pressure. 

The fact that it comes with 2 racks instead of having to buy a second one is definitely a plus, and the 10-year warranty is great!

What we like:

  • Excellent safety features for those new to pressure cooking.
  • It's huge and can produce lots of grain spawn in one sitting.
  • It is reasonably priced for the size of the unit.
  • The product reaches the correct pressure fast.
  • Superb warranty.

 What we don't like:

  • The older units do not contain a pressure gauge in PSI but instead a setting of 1,2,3.
  • The unit is heavy and could be difficult for some people to use.
  • The user manual is not the greatest.

Best for: Mushroom Farmers or professional mycologists. 

Material: Aluminium.

Size: Large. 18.5 inches Tall, 16.1417 Inches Diameter, 23.6 Litres

Weight: 6.7kg

Racks included: 2

Hob Type: Gas

Available Location: USA, UK (eBay only).

Full pressure time: 10 minutes.

Warranty: 10-year limited warranty.

Capacity

Capacity (US Measurement)

Capacity (Metric Measurement)

Wide Mouth.

Wide Mouth.

38 x US ½ pint Jars.

38 x 240ml jars.

19 x US 1 Pint Jars.

19 x 500ml jars.

Regular Mouth.

Regular Mouth.

38 x US ½ pint Jars.

38 x 240ml jars.

19 x US 1 Pint Jars.

19 x 500ml jars.

6 Large Spawn Bags.

 

The All American 925 25 Qt Autoclave isn’t really a pressure cooker, it's a sterilization autoclave.

However, we have included it in the list because it basically does the same thing and it's PERFECT for mushroom grain sterilization.

This is the kind of unit you would find in a lab sterilizing utensils and is built for purpose. 

The All American 925 has been built with excellent craftsmanship and does not contain a rubber seal but instead depends on the engineering of the lid to create a metal-on metal seal. 

It also includes 2 racks which is ideal, this means you can double stack your jars and fill the unit with at least 26 jars without needing to purchase additional racks. 

If you are considering creating your own spore syringes, liquid cultures, grain spawn, or agar plates to sell and trade this is probably the unit you are going to want as it guarantees sterilization.

This unit does look very intimidating so it's important to ensure you are using it correctly, read the manual and watch as many videos as possible before using it. 

The basic steps for use are:

  • Place 2 – 3 inches of water in the unit (this unit uses less water than others).
  • Lubricate the metal to metal seal with a Q-tip of olive oil.
  • Tighten down the cover using the 6 sealing screws. It's best to tighten opposite screws, one after the other.
  • Put the autoclave on the burner and turn to high heat.
  • Place the regulator weight on the 15psi setting.
  • Look out for any leaking.
  • Wait for the regulator weight to jiggle when you are up to pressure then watch the PSI gauge.

 What we like:

  • Excellent safety features for those new to pressure cooking.
  • It’s massive.
  • Impressive pressure gauge.
  • It is built for sterilizing.
  • Great customer service.

What we don't like:

  • It only has a 1-year warranty.
  • It takes some more management before use (remembering to oil the seal etc).
  • It is heavy, which means it isn't guaranteed to work on non-gas stoves safely.

Best for: Mycologists without access to US products.

Material: Aluminium.

Size: Large. 19.01 inches Tall, 15.9 Inches Diameter, 2 Litres

Weight: 9.8kg

Racks included: 1

Hob Type: Gas

Available Location: Global.

Full pressure time: 10 minutes.

Warranty: 5-year limited warranty.

Capacity

Surprisingly, capacity for this pressure cooker is not as great as it sounds, 22L makes it sound huge, however when you put the lid on (or inside in this case) it means that there needs to be a few inches left at the top of the pressure cooker to fit it in.

Capacity (US Measurement)

Capacity (Metric Measurement)

Wide Mouth.

Wide Mouth.

24 x US ½ pint Jars.

24 x 240ml jars.

16 x US 1 Pint Jars.

16 x 500ml jars.

Regular Mouth.

Regular Mouth.

24 x US ½ pint Jars.

24  x 240ml jars.

16 x US 1 Pint Jars.

16 x 500ml jars.

3 Large Spawn Bags.

 

Overall this is a great pressure cooker for those who don't have access to other large models. It runs at 15psi only which is perfect for sterilizing. 

I've noticed the lid is a bit of a faff to get on as you have to place it inside the opening then lift it up and turn it to seal, however, once you’ve mastered that it's pretty simple to use. 

Once turned on and heated the pressure regulator on the top will pop up and whistle loudly like a train, let it whistle 3 times then I'd turn the heat down to maintain pressure.

The Hawkins Big Boy is fairly heavy at 9kg which is probably the heaviest for its size on the list so bear this in mind.

One perk is it is available globally unlike the other units so you don't have to pay crazy import and shipping fees if you live outside of the US, this brings the cost of the unit down greatly in comparison to other competitors.

What we like:

  • Simple to use.
  • Available globally.
  • Guaranteed 15 PSI working.

What we don't like:

  • The lid is a bit of a faff to get on and uses some of the jar space.
  • Gas only means it's not right for everyone.

Medium options (10-18 Quart)

Best for: Beginner Mycologists.

Material: Aluminium.

Size: Large. 17 inches Tall, 11 Inches Diameter, 15 Litres

Weight: 4.5kg

Racks included: 1

Hob Type: Electric, Gas, Smooth top, Induction.

Available Location: US, UK (eBay only).

Full pressure time: 10 minutes.

Warranty: 12 Year limited warranty.

Capacity

You can't double stack in this pressure cooker, however it is possible to create a base layer then place a few jars on top on their sides, as show in the picture we took during our testing below.

16qt presto pressure cooker capacity test for mushrooms.

Capacity (US Measurement)

Capacity (Metric Measurement)

Wide Mouth.

Wide Mouth.

14 x US ½ pint Jars.

14 x 240ml jars.

12 x US 1 Pint Jars.

12 x 500ml jars.

Regular Mouth.

Regular Mouth.

14 x US ½ pint Jars.

14  x 240ml jars.

10 x US 1 Pint Jars.

10 x 500ml jars.

2 Large Spawn Bags.

The presto 16 qt pressure cooker is probably the best medium-range unit for a newbie mushroom cultivator. 

The product is not so big that it's hard to store and move around but it is large enough to make a decent amount of grain spawn in one sitting. 

It comes with a pressure gauge and regulator which ensure you can reach 15 PSI. 

Presto has a great reputation among mycologists and this is often the top recommended beginner pressure cooker. 

Most people who buy this model will never outgrow it and are pleased with their purchase. 

What we like:

  • Accessible price.
  • This product reaches 15PSI fast.
  • Superb warranty.
  • The pressure Gauge ensures you see that you have reached sterilization levels.

What we don't like:

  • This pressure cooker regulator can be very noisy if you don't get the temperatures perfect at 15psi. It will go over and rattle like mad basically.
  • This pressure cooker uses a manual pressure regulator which may be daunting for new users as they have to place the pressure regulator on a steam vent whilst cooking.
  • Only fits one stack of jars.

Best for: Safety Concerned Beginner Mycologists.

Material: Stainless Steel.

Size: Large. 12 inches Tall, 11.6 Inches Diameter, 12 Litres

Weight: 4.5kg

Racks included: 1

Hob Type: Electric, Gas, Smooth top, Induction.

Available Location: US.

Full pressure time: 10 minutes.

Warranty: 10 Year limited warranty.

Capacity

You can't double stack in this pressure cooker, however it is possible to create a base layer then place one or two extra jars on top on their sides.

Capacity (US Measurement)

Capacity (Metric Measurement)

Wide Mouth.

Wide Mouth.

12 x US ½ pint Jars.

12 x 240ml jars.

10 x US 1 Pint Jars.

10 x 500ml jars.

Regular Mouth.

Regular Mouth.

12 x US ½ pint Jars.

12  x 240ml jars.

10 x US 1 Pint Jars.

10 x 500ml jars.

1 Large Spawn Bags.

 

In a similar fashion to the T-fal unit discussed earlier the Zavor EZLock pressure cooker has a really great safety profile, especially for anyone new to the sterilization process. 

The lid is placed on and locked using the top handle in an innovative way I haven't seen before on pressure cookers. 

It includes a safety vent that helps release excess pressure when the pressure is building.

The cooker is a bit less intimidating than the presto units as you don't need to place a pressure regulator on top to build pressure.

The EZLock pressure cooker is easy to use, you just set the correct pressure on a pressure dial and heat, the pressure cooker will then reach the correct heat, begin hissing, then you can turn down the heat to maintain pressure.

You can get 4 1 quart jars inside the cooker which can create a good amount of spawn in one sitting.

The pressure cooker is made from stainless steel and is a really solid unit, it comes with a 10-year warranty. 

Finally, (and most importantly) the high setting on this product reaches 15 psi for sterilizing. 

What we like:

  • Great safety profile.
  • Innovative lid.
  • Superb warranty.

 What we don't like:

  • Price – this model can be quite pricey in comparison to other brands.

Small options (6 – 8 Quart)

Best for: Mycologists looking for a simple setup.

Material: Stainless Steel with aluminium base.

Size: Large. 8 inches Tall, 8.5 Inches Diameter, 15 Litres

Weight: 1.7kg

Racks included: 1

Hob Type: Electric, Gas, Smooth top, Induction.

Available Location: US.

Full pressure time: 10 minutes.

Warranty: Lifetime warranty.

Capacity

Capacity (US Measurement)

Capacity (Metric Measurement)

Wide Mouth.

Wide Mouth.

6 x US ½ pint Jars.

6 x 240ml jars.

3 x US 1 Pint Jars.

3 x 500ml jars.

Regular Mouth.

Regular Mouth.

6 x US ½ pint Jars.

6  x 240ml jars.

2 x US 1 Pint Jars.

2 x 500ml jars.

1 Medium Spawn Bag.

The Cuisinart CPC22-8 is an 8-quart pressure cooker that contains the same type of lids as the Zavor EZlock.

This means it has an excellent safety profile for new mycologists who are worried about the safety of pressure cooking. 

This pressure cooker can be picked up very cheap so it’s great for someone who isn’t sure about mycology as a hobby and just wants to get their feet wet without spending too much money.

The product hits 15psi so you should be able to sterilize grain jars. However, it is on the small side so you are only going to be able to get a few small jars created at once. 

This pressure cooker is probably best placed with someone who doesn't have lots of room to store big pieces of equipment and is only going to use the unit a few times a year.

What we like:

  • Great safety profile.
  • Innovative lid.
  • Superb warranty.
  • Great Price

What we don't like:

  • Small – you won't get a lot of spawn from this model.

Best for: Mycologists looking for the cheapest possible setup.

Material: Aluminium.

Size: Large. 7 inches Tall, 9.5 Inches Diameter, 15 Litres

Weight: 2.2kg

Racks included: 1

Hob Type: Electric, Gas, Smooth top, Induction.

Available Location: US.

Full pressure time: 10 minutes.

Warranty: 1 year warranty.

Capacity

Capacity (US Measurement)

Capacity (Metric Measurement)

Wide Mouth.

Wide Mouth.

6 x US ½ pint Jars.

6 x 240ml jars.

3 x US 1 Pint Jars.

3 x 500ml jars.

Regular Mouth.

Regular Mouth.

6 x US ½ pint Jars.

6  x 240ml jars.

2 x US 1 Pint Jars.

2 x 500ml jars.

1 Medium Spawn Bag.

What we like:

  • Ultra Low price.
  • Presto great quality.
  • 15 psi.
  • Easy to use handle and lid system.

What we don't like:

  • Small – you won't get a lot of spawn from this model.
  • Short warranty for a presto model.

Do you have recommendations for the UK Mushroom growers?

Small

Tower T920004S7L Express 7 Litre Pressure Cooker

This is the size pressure cooker I started out with its cheap and can hold about 8 half pint jars. This is a well built system and are designed to ensure safety as a priority, this can be a huge benefit to people new to the sterilization process.

Medium

14l HAWKINS Bigboy Aluminium Pressure Cooker

This is a large GAS HOB ONLY pressure cooker it can fit a fair amount of jars or substrate bags inside of it. Read the note below first before purchasing though.

Large

22L Hawkins Big Boy Gas Only Pressure Cooker

This is another whopping pressure cooker, comparable to the large presto cookers. However this is a GAS ONLY pressure cooker so no luck if you have an induction hob. This one is also confirmed to reach 15PSI. Read the note below first before purchasing though.

Note: Hawkins pressure cookers are manufactured in India this means some of the sellers on amazon may be sending them from India. This will incur custom charges when the item reaches the UK.

To avoid  this find the “other sellers” section on the right hand side of amazon and look for a UK seller.

Presto 23 Quart Pressure Cooker (eBay affiliate link)

You can find the 23 Quart Pressure cookers by presto on eBay for importing from the USA. You have to pay a little bit extra for shipping but the price is definitely still resonable. The are very large pressure cookers which can hold at least 20 half pint jars at once.

Sterilization Units for mushroom farm cultivation.

All-American 25 Quart Non-Electric Sterilizer

If you are creating a business based around mushroom cultivation then you are probably going to need to maximize your sterilization efforts. This is a proper sterilization unit (known as an autoclave) you would find being used by commercial laboratories. You could fit many spawn bags in this system and it is specifically made for sterilization. It is also possible to get these units as all in one electric systems which is actually really useful albeit pricey.

Do you need a Pressure Cooker for growing mushrooms?

Technically no, for some mushrooms strains such as oysters it is possible to use pasteurized substrates. However, for the majority of strains and substrates it is recommended to sterilize the substrate to give the mycelium a good chance of colonizing to 100% without contamination.

If you want more consistent results and to grow an array of different strains it is always recommended to use a pressure cooker.

What size Pressure Cooker Is needed for  Growing mushrooms?

The minimum size pressure cooker needed for mushroom growing is 6 Quart, this will allow you to get 6 half-pint Jars sterilized at one time.

Anything below this will greatly reduce your margin for error and increase the chances that you won't produce any mushrooms from you're sterilization run.

What to look for in a Pressure Cooker for growing mushrooms?

Size – ensure the product you're looking at can fit a decent number of mason jars inside. The more spawn jars you can sterilize the more mushrooms you can grow.

Pressure – Ensure your pressure cooker can reach 15PSI, this is level of pressure required to bring the temperature inside the pot to sterilize the substrate. In Europe it is harder to find a pressure cooker will reach the full 15PSI but it is not hard to find a product which can push pressure to 14+PSI (just leave your jars to sterilize longer if so).

Hob Type – Ensure the pressure cooker will function with the type of hob you have. There are plenty of options which can be used on all hob types however its always best to check as some can not.

Things to bear in mind.

  • Ensure the pressure cooker does not run out of water while functioning.
  • Never block the vent on your pressure cooker.
  • Regularly clean and maintain your pressure cooker.
  • Do not remove your sterilized jars until the pressure cooker has cooled.

Why is a Pressure Cooker important in mushroom cultivation?

In short, pressure cookers sterilize the substrate destroying harmful contaminants which could compete with your Mycelium.

Pressure cookers are important when growing mushrooms as they sterilize the different substrates which the Mycelium is going to eat. Contaminant such as mold spores, bacteria and other fungi spores are everywhere and the substrates we use during mycology are the perfect nutritional meal for them. When the correct moisture and nutritional conditions are met (after we soak the substrates) the spores and bacteria germinate and multiply, taking over your substrate.

By heating our substrates to a high temperature in the pressure cooker we are destroying the spores and bacteria which may have been present on the substrate. This will give the mycelium you introduced into the substrate a head start to establish itself before reintroducing the substrate to the contaminated open air again.

How to use a Pressure Cooker for mushroom cultivation?

In this section, I am going to do a brief outline of how you would use a pressure cooker to sterilize jars, spawn, substrate bags or other growing utencils.

1. Examine Pressure cooker

As discussed in most pressure cooker user manuals it is usually a good idea to inspect your pressure cooker every time before use. Failing parts could be dangerous. 

These are the things I like to check before beginning:

Cleanliness – Is the pressure cooker free from residue and build up, particularly around the inside of the lids.

Clear safety valve – Is the safety valve clear and working correctly? When the items I am sterilizing are inside the pressure cooker does it block the safety valve? 

Rubber sealing ring – Is this clean and free from residue? Is there any damage to the ring which may cause leaks? Is underneath the ring clean?

Opening/Closing mechanism – Is this working as intended and free of obstructions (such as your jars).

Best pressure cooker for mushroom cultivation, capacity

2. Fill Pressure Cooker with Water

Whatever pressure cooker you purchase in the end should have a minimum and maximum fill suggestion displayed on the inside of the cooker. When you are first using your pressure cooker I would suggest filling it up to at least the minimum line as suggested in the manual.

If you are wondering how much water to use in a pressure cooker while sterilizing PF tek then just fill the pressure cooker with water until the minimum line (around 2 pints). This is a safe measure until you fully understand how to maintain pressure in the cooker during the process.

Once you become more confident with the pressure cooker you can work with smaller volumes of water in the pressure cooker as you learn how to maintain pressure without drying the cooker out.

3. Insert Items

In Short: Place items into a pressure cooker, ensure the lids are covered with foil. The items should be raised from the bottom and not touching the perimeter.

It's time to place all the items you wish to sterilize into the pressure cooker.

Normally I use the vegetable rack which comes with the pressure cooker and place that on the bottom of the pressure cooker.

If you don’t have one of these you can line the bottom of the cooker with the rings from the mason jars. The main purpose is to raise the items from the bottom of the cooker to avoid them from contact burning.

As mentioned earlier ensure that the safety valve is not being blocked by any of the items and it is still possible to open and close the pressure cooker with the items inside. 

Ensure that your items are not touching the perimeters of the pressure cooker some people like to put a damp cloth around the outside of the items to ensure a barrier remains.

Best pressure cooker for mushroom cultivation, capacity

4. Seal the pressure cooker

Perform one last check of the Pressure Cooker lid, mechanism, and the contents inside. 

Wipe down the outside and bottom of the cooker to ensure no water or food has splashed onto the bottom (I always make a mess).

Finally, close the pressure cooker and apply the correct setting.

5. Heat the Cooker until hissing.

Now, this section is pretty dependent on the type of Pressure Cooker you have but the general consensus is to put the cooker on full heat until the pressure builds up and it begins to hiss.

Once the pressure is maintained (hissing for 10 minutes) turn the cooker down too low to maintain the pressure (for me this is not the bottom dial but the 3rd tick).

This will maintain the pressure while preventing all the steam from escaping and drying out the cooker, resulting in lost pressure.

Leave to sterilize for the time in which it is required for your tek. Once finished turn off the heat and leave to cool overnight.

NOTE: LEAVE THE COOKER TO COOL OVERNIGHT DO NOT OPEN IT UNTIL THE CONTENTS HAVE COOLED THIS CAN RESULT IN ISSUE WITH YOUR SUBSTRATE.

6. Clean after each use.

Once you have finished with your pressure cooker clean it to ensure it is ready for the next use. This will also reduce the cleaning and checking needed for the next time you use it.

It is always a good idea to maintain the most prized possession in your mushroom cultivation arsenal, so look after your pressure cooker and always refer to the manual FIRST!

What materials can be used inside a pressure cooker?

I am in no way a pressure cooker safety expert when it comes to items that can be used inside of a pressure cooker. It is always best to refer to the manual for this sort of information before taking advice on the internet.

However….

I can tell you a few items which I regularly use inside my Pressure Cooker without issues:

  • Glass Jars/Beakers – I use these all the time while making grain Jars.
  • Mushroom Cultivation bags – Designed for pressure cooking.
  • Plastic containers that display the 5PP symbol as shown here
  • Turkey Bags – I use this for sterilizing/pasteurizing bulk substrates as I can reuse them.
  • Tinfoil and elastic bands – These always go over the top of the Jars I'm using.
  • Syringes – These can be sterilized when wrapped in tin foil however there are easier methods out there for this.
  • Poly Fill/Micropore Tape/EZ felt (with RTV silicone) – These generally make up the contamination barrier on my lids.

How long to Pressure Cook Grain spawn?

15-PSI for at least 90 Minutes.

When working with grain spawn you want to leave the quart grain jars to sterilize for at 15-PSI for at least 90 minutes, this should be a sufficient enough time to eradicate contaminants and spores.

If you are using a lower PSI like 10-12 PSI the sterilize for 2.5 hours (although 15 Psi is always recommended).

Here are posts I have created on Popcorn Grain and Rye grain spawn.

How long to Pressure Cook Agar

15-PSI for at least 20 Minutes.

Agar will heat and sterilize in about 20 minutes, this is due to agar being made up mostly of liquid. Once complete it can be removed and then allowed too cool before use.

If you dont know how to make agar please see this post here.

How long to Pressure Cook PF-Tek

15-PSI for atleast 60 minutes. 10 – 12PSI for 2 hours.

PF-tek is a pretty easy substrate for beginners. It can be sterilized in a shorter period of time to grain jars. Alongside this you can even use a lower PSI for a longer period of time with PF-Tek.

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