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Bucket Tek for Mushroom Grow Sticks

Extend the fruiting life of mushroom grow sticks

Get bonus mushrooms from your twice or thrice-flushed grow sticks using this straw bucket technique

Pictured left – Chestnut Mushrooms | Pictured right – Golden Oysters

Here are our step-by-step instructions. In a nutshell, you simply crumble your grow stick into a holed bucket with pasteurised cut straw, then wait and watch it fruit yet again!

The 10-litre bucket is suitable for either one or two grow sticks at a time. You can mix varieties if you wish.

The 5-litre bucket is suitable for one grow stick at a time.

Things you’ll need:

  • A 10-litre or 5 litre bucket (with some 10mm holes in the sides and one in the base)
  • A large tub or bucket to soak the straw in
  • Straw (500g for the 10L bucket; 250g for the 5L bucket)
  • Tap-water (12 litres for 500g; 6 litres for 250g)
  • Hydrated lime (18g for 10L bucket, 9g for 5L bucket)
  • A clean flat surface to drain the straw once soaked
  • 1 or 2 spent (or half-spent or new) mushroom grow sticks

Step-by-step instructions:

Step 1: Cut the straw into pieces of about 5-8cm
This facilitates both pasteurisation and colonisation. The smaller pieces make the nutrients in the straw more accessible to the mycelium, making it easier for the mycelium to work its way through. 

Step 2: Prepare the water
Half-fill a container with tepid tap water and stir in the hydrated lime. If the lime is lumpy, dissolve it in a little hot water first. The ratio of hydrated lime to water is about 6g to 4L. Hydrated lime can irritate the skin and lungs so we recommend wearing gloves and a mask while mixing it.

Step 3: Add the cut straw and soak for 12-24 hours
Make sure the water is soaked throughout the straw. Place something heavy on top to keep it submerged otherwise parts of it will float above the water and not get properly pasteurised.

Step 4: Remove the straw from the water and drain
Spread it out slightly on a clean surface for 5 minutes to let most of the water drain off. You want it damp but not soaking wet. Don’t leave it out longer as it will 1) pick up new contaminates, and 2) get too dry for the mycelium to use.

Step 5: Crumble the grow stick
After washing your hands thoroughly, remove the plastic from your grow stick and crumble the contents gently. You could also skip this step, and crumble it directly into the bucket as per Step 6.

Step 6: Mix the pasteurised straw and crumbled grow stick into the holed bucket
Start with the straw, alternate with layers of straw and grow stick until the bucket is full. Firmly but gently press down each layer as you go. There’ll be a lot more straw than grow stick, so don’t expect your grow stick layers to be substantial. Spread them evenly over the straw. Put the lid on, and place the bucket on a drip tray.

Step 7: Cover the holes with paper tape for colonisation
You can use micropore, transpore or 3M gauze tape. This prevents the contents from drying out, and aids colonisation. This step is optional.

Step 8: Leave to colonise for 10 – 14 days
You will now simply leave the bucket for 10 – 14 days while the mycelium colonises the straw. It will help if you place it in a darker place than where you will be fruiting it, but this is optional. The mycelium will colonise faster without light, but it does need at least a little air, so don’t wrap it up in plastic. If it’s winter, try to keep it in your house rather than in a cold shed while it colonises. If you plan to fruit your bucket outdoors, rather keep it indoors for the first two weeks to aid colonisation.

Step 9: Trigger fruiting
Move your bucket into a spot that has adequate daylight and fresh air exchange (FAE). Avoid direct sun, wind or constant breezes. Remove the tape, and mist the holes lightly. You do not need to mist the bucket as often as you did the grow stick. It is helpful but optional to get a slightly larger drip tray and put a layer of perlite around the base of the bucket, keeping the perlite moist so that it is continuously releasing moisture around the bucket.

Step 10: Harvest
Once the fruits look ready (about four days after pinning), harvest each cluster by twisting and bending at the base. You may need a small sharp knife to slice off at the base if it doesn’t break easily.

Bucked Tek Chestnut

Step 11: Leave to rest and possibly fruit again
If there are no fruits peeping through any of the holes after about two to three weeks, it’s time for the contents to fertilise your garden. Note that it will sometimes surprise you and grow more fruits many weeks after you thought it was done. So you can take your time about throwing it out. You will know if it’s starting to look stale and has nothing more to give.

Tips and extra info:

  • The volume of the straw will be quite a bit less after it’s soaked.
  • The colour of the straw becomes more yellow/gold after it’s soaked.
  • The hole on the base of the bucket allows any excess water to drain off.
  • If fruiting in a garden, be sure to bring inside or harvest as SOON as the fruits are nearing ready – garden bugs tuck in fast.
  • Preferably keep under cover (house, garage, shed, greenhouse) to colonise – about 10-14 days.
  • It’s safer to keep it under cover all the way through fruiting, but if you’re adventurous, the weather is mild, and you have a suitably sheltered spot in your garden, go for it.
  • Although mycelium and mushrooms need fresh air, a constant wind or breeze dries them out.
  • The condition of the mushrooms will tell you if they are getting dried out. They will crack slightly. If you are in a very dry climate, and you already have soaked perlite in your drip tray, you can place a larger holed bucket or dome of some sort over the bucket to try and hold the moisture around it.
  • If the mushrooms are long and leggy, they are likely not getting enough daylight.
  • Mushrooms do best with more or less 12 hours of light and 12 hours of darkness. They don’t enjoy constant light.

Notes on pasteurisation, for the curious

We chose this method as it’s an effective, simple and cheap way to prepare straw as a mushroom substrate. The hydrated lime rapidly increases the pH of the water thereby killing off unwanted contaminants, and the mycelium is able to colonise and fruit unhindered by other competing organisms, at least for a while. As mycelium is more resilient in high pH environments than the unwanted contaminants are, it gets the upper hand. The pH does gradually reduce over the next few weeks, but by then the mycelium is thoroughly dominating the straw.

Hydrated Lime is Calcium Hydroxide (not Calcium Carbonate). It’s usually only available at growing hobby shops or some agricultural stores. The lime that’s typically found at garden centres for treating garden soils is Calcium Carbonate (also known as dolomitic lime, garden lime, quicklime, limestone, or chalk) and will not raise the pH of the straw high or fast enough to kill the unwanted spores. Also, it’s high in magnesium which will retard the growth of your mushroom mycelium.


Cut straw is soaked in 65°C water for 90 minutes.

Wood ash works in a similar way to hydrated lime, by raising the PH enough to kill off contaminants.

This is done in a very similar way to cold water lime pasteurization. 

There are two groups of contaminants that hinder mycelium growth –aerobic (need oxygen to survive) and anaerobic (need a complete lack of oxygen to survive). The substrate is therefore soaked in water, drained and placed in a well-sealed container, causing the aerobic contaminates to die. When the container is opened the anaerobic contaminants die.

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