Grow Kit Troubleshooting Guide

We are unable to provide support by email, but we’ve created this comprehensive troubleshooting guide to help you identify and solve common issues with your grow kits.

1. Important Notes

Product Terminology

Whenever we speak of SpawnTubs, we are also referring to other spawn products such as the smaller SpawnPots. Similarly, MonoBox, MiNO, and other substrate products are basically the same thing, with the main difference being container size and shape.

Temperature Is Critical

If you cannot keep your house warm, you are going to struggle growing mushrooms unless you build or buy an incubator. Temperature is mentioned throughout this guide because it’s one of the most common reasons for failure.

Legal Disclaimer

When we speak of spores and mushroom cultivation, we are speaking of legal mushroom cultivation with gourmet species of mushroom. We will never provide advice for species which are illegal to grow, and this also includes our entire ‘for microscopy’ range. Research the law.

2. Spore Syringe Issues

Can’t See (M)any Spores

So you’ve got a gourmet spore syringe from a vendor, but you can barely see anything in the syringe? First off, don’t panic. As long as you bought your gourmet spore syringe from a reputable vendor, your syringe will probably be A-OK.

It might sound a bit of a no brainer to some, but for those new to the microscopy scene who haven’t invested in their ‘scope yet, any dots you can see aren’t individual spores — those are clumps of spores that you’re seeing.

A typical spore syringe has tens, maybe hundreds of thousands of spores. And just because you might not be able to see each of them with your naked eyes, doesn’t mean they aren’t there.

If you don’t have a microscope to verify the spore syringe has plenty of spores, then think about who you’re buying the syringe from — are they established with actual genuine customer feedback? For gourmet spore syringes, focus on getting as clean a syringe as you can from as trusted a vendor as you can, then make sure you are inoculating properly and following the correct temperatures.

3. SpawnTub Issues (Before Inoculation)

Contaminated SpawnTub

If you’ve received contaminated spawn, do not open it because you may need to send it back to us. Rest assured that contamination is extremely rare and we will fix it immediately, so get in touch.

Our process includes sterilisation at 121°C for 90 minutes in an autoclave, handling in a cleanroom with a 12ft laminar flow hood, and using desiccant sachets to eliminate residual moisture. While comprehensive, no system is perfect, and we appreciate your understanding if issues arise.

Physical Issues

Warped Container: Some spawn containers become a little warped after coming out of the autoclave. If you believe the spawn container is so bad that it’s unusable, do not remove it from the packaging but get in touch immediately.

Cracked Container: If you notice a cracked spawn container before you’ve used it, contact us immediately.

Wet Appearance: Sometimes our spawn products are freshly out of the autoclave when shipped. When spawn products are this fresh, the grain inside them can appear a little wet for the first couple of days. Give the spawn a shake so that moisture absorbs into the grain. The desiccant sachet will help dry out excess moisture over time.

4. SpawnTub Issues (After Inoculation)

Contamination

Contamination affects every spore syringe in some way, but most of the time it poses little threat to your grow. The weakest link in the entire chain is usually the end-user’s setup and technique.

If you want to have near perfect results every time, invest in a Cleanroom, laminar flow hood and develop years worth of experience in this hobby. For most home growers, building or buying a Still Air Box (SAB) and learning to use it properly will give you around 90% success.

Never underestimate the importance of temperature. Follow correct temps so that the environment favours the mycelium rather than microbes. Try to avoid reusing syringes if you can. If reusing a needle, flame sterilise until it’s glowing red hot. Never wipe needles with alcohol wipes, they will not sterilise a needle properly.

Don’t mistake natural waste products of mycelium (metabolites/yellowing) as being contamination; it’s quite normal to see in your spawn. And leave the SpawnTub well alone. Keep it in the box. Don’t keep touching it.

Nothing Is Happening

So you think nothing is happening because you can’t see mycelium, but are you really sure? Look for common signs of contamination like sweating or condensation – that sometimes suggests heat is being generated from active microbe growth inside.

A sure way to detect contamination is smelling around the SpawnTub filter for anything peculiar. If you are certain there’s no contamination, it could be down to the particular species being a slower coloniser, or genetics.

Impatience: Being part of the mushroom community for 20+ years, we know impatience is rife. But impatience is likely to ruin a grow if not controlled. Leave the SpawnTubs alone and forget about them – stop handling them, keep them totally still and clean.

Dead spores? First off, dead or inactive spores are rare unless they are very very old. We’ve injected gourmet spores into a boiling hot SpawnTub for fun and watched it grow with healthy mycelium. We even froze a spore syringe once, thawed it and used it successfully too. It’s pretty hard to kill spores unless you’re trying to.

Stalled Growth

Sometimes your SpawnTub is progressing as planned, then suddenly stops. First, confirm it has truly stalled by tracing around the mycelium line with a Sharpie and checking after a couple of days. Slow growth isn’t the same as stalled growth.

Temperature: Mycelium will stop growing (or slow down dramatically) when it’s cold. But microbes won’t stop growing, which can lead to contamination taking over. If your temps are too high, too low, or unstable (leading to excess condensation), microbes can outrun your mycelium.

Shaking the SpawnTub: Shaking to speed up colonisation is standard practice, but it comes with risks. Mycelium sometimes stalls for no apparent reason after shaking, or microbes manage to get in through weakened seals during agitation. The rim of the lid and HEPA filter are weak points in the SpawnTub design. If you shake, be aware of the risks and keep it to an absolute minimum for the highest success rates.

Weak mycelium: Sometimes mycelium is just too weak to recover from a shake. If you want to avoid this, don’t shake the grain to try to speed up colonisation. Your times will be slower but your overall success rate higher.

Best Practices for Syringe Handling & Inoculation

Do

  • Purchase spores from a vendor you trust
  • Remember individual spores are too small to see without a microscope
  • Keep syringe handling to a minimum and only when necessary
  • Make or buy a SAB (or Flowhood) for inoculations
  • Inoculate with new, clean surgical face mask and gloves
  • Rattle syringe to unstick and distribute spores
  • Remember the last squirt of a syringe contains most spores
  • Incubate at a consistent, recommended temperature
  • Flame sterilise needle between SpawnTubs when reusing

Don’t

  • Rush inoculation – plan for cleanliness and efficiency
  • Flame sterilise an already sterile needle
  • Try to ‘sanitise’ or ‘sterilise’ a needle with alcohol wipes
  • Touch the rim of the SpawnTub lid or HEPA filter – ever
  • Inject too much solution – 3ml syringe per SpawnTub max
  • Think spore syringes are totally free of contaminants
  • Use a spore syringe from an untrusted vendor
  • Break the law with our products

5. MonoBox Issues (Before Full Colonisation)

Temperature Problems

Too Low: Low temperatures will slow mycelial growth, and even lower will stall growth completely. When microbes keep growing at their normal rate while the mycelium is growing slowly, things can get out of control quickly. Mushroom mycelium is stronger and faster than most microbes, but only in the right temperature conditions.

Too High: There’s a whole world of microbes which love holidaying in the heat. If you are hitting incubation temps of 28°C+, you can expect microbes to grow exponentially. Keep temperatures in the recommended range to avoid bacteria and other contaminants overrunning your MonoBox.

Too Unstable: When we give a temperature, we mean a stable, consistent temperature – not one which fluctuates throughout the day. Unstable temperatures cause excess condensation, which promotes microbial growth since microbes love water.

Other Common Issues

Bad Spawn: Only use spawn that is 100% colonised. Even a few loose, uncolonised grains can lead to contamination. Inspect thoroughly and check for any unusual odors. Earthy mushroom smells are good; sour, sweet or anything else is bad.

Environmental Factors: The general cleanliness of your home matters. Never open contaminated or mouldy foods nearby. Be careful with vacuums as they can spread contaminants. Avoid kitchens, bathrooms, and dusty areas for growing.

Weak Mycelium: While rare, sometimes mycelium is just genetically weak. Not much can be done except starting over.

Dirty Substrate: When preparing substrate, always use a clean microwave. Different microwaves have different power levels, so if in doubt, give your substrate a couple of minutes longer cooking time than our instructions recommend.

6. MonoBox Issues (After Full Colonisation)

Fruiting Problems

Temperature Issues: Temperature during fruiting isn’t as contamination sensitive as during incubation, but still important. For the mycelium to develop hyphal knots (pins), you need to maintain a good fruiting temperature.

Substrate Not Fully Colonised: The MonoBox should only be moved to fruiting when it’s 100% covered in white mycelium throughout. It won’t harm to give the colonised MonoBox a few extra days to be certain.

Water Pooling: Cool temperatures slow evaporation while warm temps increase it. Standing water can become contaminated quickly. If you see water pooling on the substrate, dab it with a paper towel. Ensure there’s enough fresh air exchange to promote evaporation without drying out the cake.

No Pins or Poor Fruiting

If your fully colonised MonoBox isn’t producing pins or mushrooms:

Incorrect FAE (Fresh Air Exchange): Too little or too much fresh air can prevent proper pinning. Fuzzy stems indicate too little FAE.

Improper Humidity: Mushrooms need high humidity to develop properly. If your grow tent or fruiting chamber is too dry, pins may abort or fail to form.

Light Conditions: While not as critical as temperature or humidity, improper lighting can affect fruiting. Most mushrooms need indirect light to form proper fruit bodies.

Patience Required: Sometimes it simply takes longer than expected. Give your MonoBox time before concluding there’s a problem.

7. Additional Resources

If you’re still experiencing issues, we recommend visiting community forums like The Shroomery where experienced growers can help troubleshoot specific problems. With over 20 years of collective knowledge, these forums are an invaluable resource for both beginners and experienced mycologists.

Last updated on March 1, 2025