Updated: Jul 21
This blog post will teach you how to prepare a food-grade plastic bucket for growing oyster mushrooms on straw or sawdust (as well as how to grow them in special-purpose plastic bags). The bucket-method is a great eco-friendly way to produce oyster mushrooms, as the bucket can be used hundreds of times over: this method works for all species of oyster mushroom - including the Native NZ Velvet Oyster Mushroom, Pink Oyster and Grey Phoenix Oyster mushroom.
Vivid marker or pen
20mm Drill Bit / Auger - you can grab these from Mitre10 or Bunnings warehouse.
Start with a new clean 10L bucket, measure and mark where you need to drill your holes. Refer to photo below for measuring points:
Making your Oyster Mushroom Bucket
(Hole 1) - Measure 60mm from the bottom of the bucket up and mark a point.
(Hole 2) - From your first marked point, measure 65mm around the bucket's circumference -- note that vertical line on the bucket with your finger -- then measure from the top rim of the bucket down 40mm and mark a point inline with your finger that is 65mm around from the first point. (this is the second mark on the picture to the right.
(Hole 3) - From hole 1 measure roughly 130mm around the buckets circumference and mark a new point (Hole 3), continue to measure another 130mm around and mark, continue all the way around the bucket until you end up back at the first marked point (Hole 1), you should end up with 5 holes.
Repeat step 3 starting from hole 2 marked near the top of the bucket.
You should end up with a total of 10 holes in total, with the top and bottom lines of holes being off-set. This helps supply evenly distributed air to the mushroom substrate when they are incubating in the bucket.
Clean out any plastic waste from drilling and dispose of it.
You now have your bucket ready to house and grow gourmet mushrooms. The remainder of this blog post will teach you how to prepare and mix the appropriate amount of substrate - with little wastage - to fill the bucket (or plastic bag, if you are using our >> 5 step kit). The following method uses the same inputs as included in our 5 Step Kit - which uses a plastic bag instead of a bucket to house the mushroom growing substrate.
Mixing Oyster Mushroom Substrate and Filling your Bucket / Bag
Mixing Bucket (not the bucket with the holes)
Measuring Jug for water
Large spoon or scoop
Ingredients you will need to make the substrate mix:
All these ingredients are part of each of our bucket kit, 5 step kit and refill kits. You can also buy them individually if you like through our website's >> mushroom growing supplies section.
>> 2kg dry pine fire pellets (these can also be bought in 15-20kg bags from Bunnings, Mitre10, supermarkets etc). If using our "refill kits" you will need your own bag of wood pellets and we recommend buying them your local store to save on freight costs.
Bag of hydrated lime (30g) >> We have bulk lime available here.
4L non-chlorinated tap water. If your tap water is chlorinated you need to fill a vessel with water and leave it out with the lid off for 24-48 hours for the chlorine to evaporate out of the water.
Before you begin making up the mushroom fruiting substrate it is important to wash your hands, work-station, and utensils, with some soapy water or 70% isopropyl alcohol. This is to reduce potential contaminant moulds or fungi competing with the oyster mushrooms we want to grow.
Substrate Preparation Steps:
Measure out 4L of cold tap water and add to the mixing bucket.
Add in the 30g bag of hydrated lime to the water in the mixing bucket.
Stir in the hydrated lime gently, being careful not to powder it into the air. The lime will dissolve almost immediately. Please refer to safety instructions on info-sheet that comes with the lime/ kit for safe-handling practices. Note: Hydrated Lime is a skin and eye irritant - take care.
Next add in the 2kg of wood pellets and give them a few minutes to begin soaking up the water.
Take your bag of spawn and break it apart by rolling it between the palms of your hands -- it will break up into almost singular grain pieces. Open the 1kg bag of mushroom grain spawn and pour all of it (1kg) into the wood pellet lime-water mix.
Mix in the grain spawn thoroughly, by hand, or with large mixing spoon/ scoop.
Allow the mix to sit for about 10-15 minutes to fully soak up all the water and then mix once more.
Filling Fruiting Bags or Bucket
This section will cover both growing in plastic bags and buckets -- so just follow the section appropriate to your chosen mushroom growing method:
Plastic Bag Method:
Take the mixed substrate and fill the bag with it -- bags are sterile at manufacture and do not need to be cleaned.
Squeeze most of the air out of the bag and begin to twist the top of the bag to seal it -- it's important to get most of the air out. Once twisted tight, take the cable-tie and tie the top of the bag off -- as close to the sawdust as you can.
Now we need to put holes in the bag for the mushrooms to grow out of -- this must be done immediately. Roughly, following the steps at the top of this blog on drilling holes in the bucket version, use the same pattern for cutting holes in the bag -- use a razor blade or sharp knife to cut about 8-10 holes in the bag. Make each cut an X shaped hole with each line of the X being about 30-40mm long.
It is critical the X holes are cut as soon as the bag is made up -- mushrooms are like us: they breathe oxygen and exhale CO2. If holes are not cut promptly the mycelium on the grain may die.
Date the bag for future reference.
Move on to the instructions in the section "Incubation Period" below.
Take your bucket and fill with your prepared substrate mushroom mix -- don't worry if some falls out of the holes initially -- once filled it will hold itself in place. If you are re-using your bucket, make sure to clean it with soapy-water before refilling.
Fill the bucket (with holes) with all of the mix: our >> oyster mushroom bucket kit with 2kg of wood pellets included, makes the perfect amount for the bucket. If you need to compact the sawdust mix a little to get the lid on, simply tap the bucket on your workbench 3 or 4 times and then squeeze the lid on.
Once full put on the lid and click it on tight.
Date the bucket for future reference.
Pro Tip - Cover holes with micropore tape:
Often with the bucket growing method the sawdust or straw exposed to the air through the holes will dry out and can delay fruiting, a simple way to overcome this is simply taping over the hole's with some micropore tape.
Micropore tape is readily available at any pharmacy for about $6 a roll. The tape helps lock in moisture but still allows the mushroom bucket to breathe, the higher humidity under the tape helps to encourage more mushrooms to grow. The mushrooms will easily push the tape off when they begin fruiting and tape can be replaced after each harvest to encourage future flushes.
I highly recommend this trick for the bucket method as it can also help reduce pest issues. One roll will do many many bucket grows!
A simple Google search for 3M Micropore Tape will bring up local suppliers.
Oyster Mushroom Incubation Periods
Now our mushroom growing mix is made-up and is in its fruiting container. The mix will need to incubate for a period of time. During this time the mycelium will grow off the >> grain spawn, through the sawdust, to gather food and resources to produce mushroom fruit bodies. The fruit body of a mushroom is really like the flower of a plant. While the mycelium is the bulk of the organism and is comparable to the body and roots of a plant. With mushrooms we normally only see the flower/ mushroom fruit-body as the mycelium is underground. Growing like this we get to see what would naturally be the underground growth in real time!
Growers using plastic bags will be able to see this process as the substrate turns more and more white over time. The white stuff is not mould, it is the mushroom mycelium.
Bucket-method growers will not be able to see this early growth -- if you want to check growth you can pop the lid off for a quick peek.
Incubation time by Oyster Mushroom species
Each species of Oyster mushroom has a different incubation time:
Pink Oyster - Usually 10 days is the earliest pins (baby mushrooms) will being to form. Can take up to 40 days if temperatures are cold. Does not grow well in temperatures below 15deg -- this is typically a summer mushroom.
Grey Oyster - Usually 18-20 days is the earliest pins (baby mushrooms) will begin to form. Can take up to 40 days if temperatures are cold. Will grow year round and handles a wide range of temperatures.
Native Oyster - Usually begins pinning after 12-18 days of incubation and can take up to 40 in cooler temperatures. This mushroom will grow year round indoors but can take a long time to fruit when temperatures are below 14ish degrees.
It is important to keep your bag or bucket out of any direct sunlight during the incubation period as it will dry the mix out. Mushrooms are 90% water so we want to try to avoid moisture-loss out of the substrate.
After about a week check your bag/ bucket and spray some water-mist directly onto the holes if the sawdust has dried out. You can tell if the sawdust has dried out as it will be a much lighter shade of brown. At this time pink oyster mushrooms may be beginning to show signs of tiny mushroom pins growing out of the holes. If so, move on to the fruiting section of this blog.
If bag/ bucket has begun to pin, it's best not to spray water directly on to the pins -- even if the substrate looks a little dry, the water can damage the pins.
Once pins are visible, or typical incubation period has passed, it's time to move on to the fruiting stage.
Oyster mushrooms grow very rapidly once they begin to appear: the above and below two photos depict a typical growth rate over a 24-48 hour period. From here these will roughly double in size again every 24 hours!
Oyster Mushroom Fruiting
Fruiting is the term used in the mushroom world, to describe the period of time when the fruit body of the mushroom is developing in to the mushroom we will cook and consume.
Oyster mushrooms need reading-level light to grow fruit bodies properly, but not direct sunlight. If you are able to read a newspaper in the level of light in the room, that is more than enough light!
Ideally, oyster mushrooms like high levels of humidity to fruit. Bathrooms are the ideal place to grow your mushrooms. If you want to build a purpose-built fruiting chamber I have a guide on how to do so >> written here. For people in dry regions (like Canterbury), I'd recommend growing the native oyster in the summer months.
Alternatively, if you don't want to grow your oyster mushrooms inside the house you can grow them outdoors in the garden -- they often do well under thick greenery, such as under the canopy of pumpkins where little sunlight gets through. Outdoor-grown oysters should be harvested early, otherwise bugs will begin to eat them.
Your mushrooms will be ready for harvest in about 7-12 days after pinning -- in ideal temperatures doubling in size every day. As tempting as it may be, don't touch the baby mushrooms while they are growing.
If you are in a dry environment or have a heat pump/fire, you can lightly mist with a spray bottle 1-2xs a day -- from 1-2ft away from the developing mushrooms. Dry mushrooms will begin to go yellow and go crunchy at the edges. It is generally best to not try fruiting the mushroom in the same room as a heat pump or fire, as they often dry-out quickly.
Harvesting your Oyster Mushrooms
Your mushrooms are ready-to-pick just before, or when edges start to thin and turn up. To harvest, grab the base of the cluster, very close to the hole, and firmly twist and pull.
Many mushroom-growers underestimate just how fast mushrooms can grow each day and leave them too long before picking (this is a very common mistake). If left too long, mushrooms will begin to drop spores which can make a mess. If you're not sure whether your oysters are ready to harvest or not, it is better to harvest them earlier than you think. The quality of your mushroom crop will be better when picked earlier -- and their fridge-life will also be better. (Plus more will regrow on subsequent flushes, so total yield from your bag or bucket will be about the same overall).
After harvest, let the bag sit-dormant for up to 2-3 weeks (pink can take up to 5 weeks). Once again mist the bag's holes as it dries out -- spray water in to each hole again to encourage second and successive flushes. This process can be repeated 2-6x’s. Yield of each harvest will get less and less with each flush -- as the sawdust/ straw runs out of nutrients.
After 2-3 months of harvesting the remaining contents of the bag makes great compost and can be put into the garden. Check the old block after any rainfall as the waste substrate can continue to produce for another 6-12 months!
Bucket users at this point can clean out the bucket, order a >> bucket refill kit and make up a new mix and repeat the process for a constant supply of fresh gourmet mushrooms. Once having done a few refills you will be able to mix, and bucket/ bag your substrate in less than 20 mins -- for near effortless production of fresh gourmet mushrooms.
Below, I will cover some of the most common issues people have with the above process. For a more in-depth troubleshooting guide (with example photos) please read my post on the topic: >> "Troubleshooting Oyster Mushroom Kits".
Common Problem: Dried-out Mushrooms
Mushrooms getting too dry is probably one of the most common issues for people. There are a few things you can do to avoid severe drying out.
Fruit in a room without a fire or heating source.
Keep in a room without too much air-flow/ drafts.
Keep out of overly hot rooms and out of direct sunlight.
Mushrooms don't need much light to grow, if you can read a newspaper that is more than enough light -- often people find bathrooms or garages are some of the best places to fruit their mushrooms.
If your mushrooms do severely dry out it's ok, the mushrooms can still be consumed but are usually a bit chewy. You can simply remove the mushrooms by pulling them off, dry them fully, and use them in soups and stews later.
Once mushrooms are removed allow the bag/ bucket to sit dormant for a week or so. Then begin misting the holes once every few days again, at some point this will trigger the mushrooms to produce a new batch of pins and the process begins all over again! The water on the sawdust helps trick the mushroom into thinking there has been a rainfall and it is a good time to fruit.
Common Problem: It's been much longer than the incubation times above
If your grow-bucket or bag has been incubating for much longer than the above times then please give us an email with some photos and we will help work out why. Generally it is either because 1) the substrate has dried out too much or 2) the substrate has become contaminated (see green-growth section below) or 3) the temperature is far too cold.
For bag-growers check the size of your X cut holes. Many people make them too small and not enough oxygen gets into the bag -- simply cut a few holes a bit larger and wet the holes.
Common Problem: Green-Growth & Contamination
Trichoderma is the most common contaminating mould for mushroom growers. If you see your substrate turning green or any colour other than 90%+ white the substrate has become contaminated and should be dumped out and started over with a new batch. If you experience this issue feel free to email us some photos and we will be happy to help trouble-shoot the source of the issue for next time. (Often we will replace with a free refill kit you will just need to cover the freight costs). Generally this only happens when utensils, hands etc haven't been cleaned properly.
Common Problem: Trouble getting second, third and more flushes/harvests
Second and third flushes can sometimes be less reliable time-wise compared to the first. Pink oysters can take up to 5 weeks before they will do a second flush where as grey oysters can begin their second flush in as little as 5 days from the last harvest.
If it's been over a month and nothing is happening here are some steps to check and do:
Bag-Growers take the white bag, make sure your X cuts are roughly the correct size (30-40mm), if they are not cut some new holes now.
Get a large bucket and fill with cold tap water, submerge the whole bag/bucket best you can underwater overnight or for 6-18 hours. You will need to weigh it down with a brick or weight.
After the 6-18 hour soak period remove the bag/bucket from the water, cut a small hole or two in the bottom of the bag to allow any pooled excess water to drain. Buckets should be laid on their side to allow any excess water to drain out for about 12-24 hours.
Place bag or bucket back in fruiting location and continue misting as usual.
If no mushrooms begin to form within 7-14 days, redo the soak each 7-14 days until they begin to grow.
We are trying to mimic an autumn-rain-event and trigger the mushroom into producing fruit bodies while rehydrating the sawdust at the same time.
Practice makes Perfect
Mushroom growing is a skill that you will get better at over time. The more grows you do the faster you will be able to identify any issues and remedy them. Eventually this leads to larger more bountiful harvests with less work. If you want a constant supply of mushrooms it's best to have 2-3 buckets going -- making up a fresh bucket every 2-4 weeks. This will make a nice rotation where new buckets are producing as older buckets finish and enter the incubation period.