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Bucket Tek for Mushroom Grow Sticks

Extending the life of mushroom grow sticks

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

Pictured left – Chestnut Mushrooms | Pictured right – Golden Oysters

Step-by-step instructions follow, but in a nutshell, you simply crumble your grow stick into pasteurised straw in a holed bucket, then wait and watch it fruit yet again!

Things you’ll need:

  • A 10-litre bucket (with about eight 10mm holes evenly spaced on the sides and two in the base)
  • Another larger bucket or container (to soak the straw in)
  • Straw (enough to fill the bucket once cut – it takes up a little less space once soaked)
  • Tap-water (about 12 litres)
  • Hydrated lime (35ml [18g])
  • A flat surface to drain the straw once soaked
  • One spent (or half-spent or new) mushroom grow stick

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, and make it easier for the mycelium to work its way through. 

Step 2: Prepare the water
Half fill a 25-litre bucket with tepid tap water and stir in 35ml (18g) hydrated lime. The ratio of hydrated lime to water is approximately 6g to 4L. Hydrated lime can irritate the skin and lungs so we recommend wearing gloves and a mask while working with it.

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

Step 4: Remove the straw from the water and drain
Spread it out slightly on a clean surface for 5-10 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 not only pick up new contaminates but will also get too dry for the mycelium to use.

Step 5: Crumble the grow stick
After washing your hands thoroughly, and preferably sanitising them too, remove the plastic from your grow stick and crumble the contents gently.

Step 6: Layer the pasteurised straw and crumbled grow stick into the 10-litre holed bucket
Start with the straw, and alternate layers of straw and grow stick until the bucket is at least ¾ full, if not full.. Firmly but gently press down each layer as you go, so that there are no large air pockets or areas of very loosely packed content. There’ll be a lot more straw than grow stick, so don’t expect your grow stick layers to be substantial. Just try to spread them evenly over the straw. Put the bucket lid on. You may want to put a tray underneath to catch bits of draining water.

Step 7: Place the bucket in a suitable place
A suitable place: away from direct sun, wind or constant breeze, but with adequate daylight and fresh air exchange (FAE). It can do without light during colonisation. If you want to fruit it outside, try to keep it in a shed, garage or greenhouse for the first two weeks to aid colonisation. After two weeks or so, you can either just leave it where it is, provided there is adequate daylight and FAE, or you can move it outside so long as not in direct sun or constant breeze. In extreme temperatures or windy conditions, it will need some shelter.  

Bucked Tek Chestnut

Step 8: Mist holes after two weeks
This helps trigger pinning. If you feel like the environment is at all dry, mist lightly around the bucket now and then, but don’t get too carried away – there’s lots of moisture in the straw.

Step 9: Harvest.
Once the fruits look ready, harvest the cluster(s) by holding as close to the base as possible then twisting and bending. You may need a small sharp knife to slice off at the base if it doesn’t break easily.

Step 10: Leave to rest and possibly fruit again.
Leave bucket in a suitable spot, as per Step 7. If there are no fruits peeping through any of the holes after about two weeks, it’s time for the contents to fertilise your garden. You can open the top of the bucket to sneak a peak at the mycelium inside the bucket. If it’s looking like the straw pictured then it’s likely you still have another flush on the way.

Step 11: Once it’s time to throw it all out,
Empty the bucket directly into garden beds or onto your compost heap.

Tips and extra info:

  • The colour of the straw changes after the lime water soak – it becomes more yellow/gold.
  • If fruiting in a garden, be sure to harvest as SOON as ready, as garden bugs tuck in fast.
  • The hole on the base of the bucket allows any excess water to drain off.
  • Although mycelium and mushrooms need fresh air, a constant wind or breeze will dry them out.
  • Preferably keep under cover (house, garage, shed, greenhouse) to colonise – about two weeks.
  • It’s safer to keep it under cover all the way through fruiting, but if you’re adventurous, the weather is not too severe, and you have a suitably sheltered spot in your garden, go for it!

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, 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 contaminates.

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 contaminates die.

Next How to make a Shotgun Fruiting Chamber
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