Grow mushrooms the EZ way.

 Jars & Jar Lids Explained: A Guide for Beginner Mushroom Cultivators


This post discusses the jars and jar lids for mushroom cultivation and grain spawn production at home.This is a aspect of mushroom growing that I believe is often over complicated by beginner cultivators.

When starting out in mushroom cultivation, many people tend to buy expensive mason jars and even more expensive jar lids as they become more invested in the hobby. In my opinion, buying these expensive jars is a waste of money.

Instead, you should recycle jars and lids from the supermarket, as they are far superior to anything you can buy online. Let me explain why.

Why Supermarket Recycled Jars Are Better.

1. Cost-Effectiveness

Firstly, supermarket jars are cost-effective. Instead of spending money on expensive mason jars, you can use jars that you already have at home. For instance, jars from pasta sauces, beetroot/pickles/sauerkraut for larger jars, and jams jars for PF-tek are perfect for mushroom cultivation. 

These jars come in various sizes and are usually made from thick, durable glass that can withstand the pressure cooking process.

Remember supermarkets need these jars to transport across the world without smashing, they have to be mishandled by staff and children in the store and are often far more durable than mason jars.

2. Interchangeable Lids.

One of the most significant advantages of using supermarket jars is that their lids are often interchangeable. For example, if the jars are approximately the same size, you can switch the lids between them. 

Here’s a practical demonstration: I have a lid from a jam jar that I used for growing Cordyceps. I can take this lid and put it onto a beetroot jar without any issues. 

This might seem like a minor thing, but it's incredibly useful. If a jar/lid breaks or becomes damaged, you don’t need to buy a whole new set of lids. You can just get a new jar from the supermarket and use the lid with your existing jars. This flexibility is particularly handy when you're making specialised jar lids such as grain lids or LC lids.

3. Shapes and Versatility.

Another advantage of using supermar different things.

For instance, 400g pasta jars are ideal for the initial spawn run. Once the spawn has grown, you can transfer it to larger beetroot jars for expanded production. The small rim of the pasta jars fits neatly into the beetroot jars, making grain-to-grain (G2G) transfers more straightforward.

Smaller jars are perfect for liquid culture (LC), as they make it easier to extract the liquid culture. Additionally, larger jars that narrow towards the lid are excellent for G2G transfers because the grains shake out easier and are less likely to miss the opening or fall out.

This versatility allows you to select the perfect jar for each step of the cultivation process, ensuring optimal growth conditions for your mushrooms.

4. Contamination Control.

Have a contaminated grain jar with trichoderma inside? No need to open it carefully or sterilise it then knock all the grains out, simply put it in the bin! It was going in the bin anyway. This makes controlling your failures easier and less costly.

5. Environmental Impact.

Secondly, recycling jars is environmentally friendly. By reusing jars, you reduce waste and lessen your carbon footprint. This practice aligns with sustainable living, which is an important consideration for many hobbyists today.

Smaller Jars (Pasta sauce, etc).

These jars are great for initial spawn runs you can get around 6 of them into even a small pressure cooker or instant pot.

Large Jars (Beetroot, Pickles, Saurkraut).

These larger jars can be used for expansion of the smaller jars, because the smaller jar rim fits into the larger jar so easily it makes a G2G transfer straight forward.

Jam Jars.

Jam jars can be used for PF-tek because of the wide mouth but I often use them for growing cordyceps.

Shop & Buy Whole Mushrooms, Mushroom Powders
and Mushroom Tinctures In The UK.

Cordyceps Militaris Powder
Cordyceps Tincture

Step-by-Step Guide to Preparing Jars / Lids

Mushroom Jar Lids

I personally keep my lids as simple as possible, normally I just use a gas exchange hole covered by Micropore tape and take the lids off briefly to inoculate between the lid and rim (inside a still air box or flow hood).

Components and Purpose:

  1. Self-Healing Injection Port:
    • The little rubber stopper on the jar lid acts as a self-healing injection port. This means that when you inject liquid culture into the jar and remove the needle, the hole will automatically close up and seal.
  2. Synthetic Filter Disc (SFD):
    • Beside the injection port, you'll find a red synthetic filter disc. This serves as an air exchange filter, allowing the jar to breathe during colonization by enabling gas exchange while blocking contaminants like spores and other unwanted particles from entering the jar.

While liquid culture doesn't necessarily need a gas exchange hole for colonisation (since the mycelium is suspended in the liquid), it's essential to include an SFD or gas exchange hole in the lid. Without it, you won't be able to inject or remove liquid culture from the jar because the pressure inside the jar can't equalise when you push or pull on the syringe plunger.

1. Cleaning and Sterilising.

Before using any jar, ensure it is thoroughly cleaned removing any visible dirt. Wash the jars with hot, soapy water and rinse them well before loading them with media to sterilise.

2. Making Micropore Tape Lids.

Micropore tape lids are simple and effective for grain spawn jars.


  1. Drill a small hole in the lid.
  2. Cover the hole with two layers of micropore.

3. Making Injection Port Lids.

Injection port lids for working with liquid cultures.


  1. Drill a hole in the edge of the lid for the injection port (we put it at the edge so you can get as much liquid out as possible by tipping the jar).
  2. The hole should be smaller than the size of your injection port stopper.
  3. Push the injection port into the hole and then using pliers or a knife push the port through the hole. 
  4. The injection port will now snuggly fit into the hole and expand.
  5. Add a gas exchange hole to the centre.
  6. Cover with SFD or Micropore tape.


Recycling jars and lids from the supermarket for mushroom cultivation is a cost-effective, sustainable, and versatile approach. 

By understanding the different types of jar lids and their purposes, you can optimise your mushroom cultivation setup and achieve better results.

Using recycled jars not only saves money but also promotes environmental conservation. The interchangeability of lids adds convenience, making the entire process more efficient. Whether you're a beginner or an experienced cultivator, these tips and techniques will help you succeed in your mushroom cultivation journey.