Why Won’t My Mushroom Kit Grow? (Solved & Explained!)

Mushroom kits are perfect for some beginner level fun, but you might never get that hefty first crop promised. There are a lot of factors to consider while growing mushrooms, unfortunately the instructions might not cover all of them. Lack of humidity, suboptimal temperatures, moisture overload, excess heat, contamination are only some of the reasons why your mushrooms might never fruit.

So what is a mushroom kit?

To understand some of the problems faced while growing from your kit, we need to understand what it is exactly. The main component of your mushroom kit is the block of compost, which is usually made of peat moss, manure, rye straw, lime etc.

These nutrient rich ingredients ensure the growth of healthy mushrooms. The compost block is inoculated with a white colored mushroom mycelium culture, making it a fully colonized substrate.

Have you got the right kit?

Selecting the right mushroom kit is imperative. Try going for Oyster, Lion, Shiitake or Button mushrooms. These are generally quite resilient to unfavorable growing conditions and hence, easy to grow. Other gourmet varieties like truffles, chanterelles, boletes are hard to tame and quite picky when it comes to the environment their growing in.

There are certain species that aren’t impossible but still difficult to propagate from kits, like Morel mushrooms.

Did you store it before using it?

Mushroom kits are meant to be used as soon as their opened, if you opened the packaging then decided to leave it without storing it at temperatures little under 50°F, there’s a chance you might get a small or no crop at all. A delay of a week or two is fine but if your kit has been stored for months, then it might be time to get a new one.

Was your kit ready to be used?

If your compost block looked moldy or was speckled with white when unpackaged then it’s ready to be used. On the other hand if it looked brown, without any visible mycelium then it was probably freshly inoculated.

For the mycelium to fully colonize the block let your compost sit for a week or so at 70°F. Therefore, it’s not that your mushrooms aren’t growing, the mycelium just needed a bit more time to grow first.

Was it contaminated?

Gnats, mold and flies are a nasty thing to be around your mushrooms. Invasive molds can cause grey, green and blacks spots to appear on your spawn or casing, whereas slimy patches on your mycelium can indicate bacterial growth.

If your box came with gnats or other nasties make sure to contact the company to have it replaced.

How does humidity matter?

If your block looks somewhat dry, it’s possible that humidity might be the problem. Even though Shiitake mushrooms can tolerate low humidity, a humid climate is ideal for growing mushrooms.

The easy solution would be to get a humidifier, if not, try indirectly misting your block to increase the humidity of its surroundings. A fruiting block can also help maintain a proper environment.

DIY’ing your fruiting block

Dry and arid climates can prove to be mushroom killers. To maintain the humidity levels simply place your kit into a plastic bag with the ends at least 4-6 inches above your kit. Grab a spray bottle and mist your block as well as the plastic bag surrounding it once a day. Make sure that the top is open to the environment and not sealed.

Adjust the temperature

Extreme temperatures can prevent mushrooms from growing and can even kill the mycelium. The optimum temperature for growing most mushrooms is between 60-74°F. Anything above 86°F can kill your mycelium and temperatures below 55°F can stunt their growth or keep your mycelium dormant for some time, which is useful if you wish to store the kit.

To water or not to water?

You are only required to soak the kit initially, after that spray the exposed area until damp. 2-3 teaspoons of water or 5-10 sprays will suffice.

If you water your shrooms more than can evaporate, your mycelium will end up drowning, which is why they might not be growing. On the contrary your mycelium could not be growing if it has dried out due to high temperatures.

Is your placement wrong?

Are you having trouble making space for your kit? Well, then this might help placing your kit easier. Make sure to keep it away from any heat sources like stoves, fires and even direct sunlight, this can dry out our mycelium and keep them from growing. Also avoid placing it near other plants and moldy fruit to keep it from getting contaminated.

Waited or waiting?

If you’ve double checked every factor and nothing seems to be wrong then it just might be that you haven’t waited enough. For most mushroom kits it takes the mycelium around two weeks to grow into pins, the time may differ depending on the conditions you’re growing it in, so if it hasn’t been that long just be patient.

Make space for it to grow

You can sometimes receive your kit with some eager spawns. If your kit already has some growth make sure to properly cut off the mushrooms from the stem. Any parts left behind will actually hinder the growth of your own mushrooms and prevent them from flourishing.

The second flush takes more time than the first one, and usually contains less fruiting mushrooms. Therefore you’ll have to be extra patient and caring if your mushroom kit came with grown mushrooms.

Lost hope?

Sometimes nothing is enough. If you’ve checked the humidity, temperature, placement, air circulation and even waited long enough then there’s a chance your mushrooms might never grow. It’s okay, don’t lose hope. You can always break up the compost block and try propagating mushrooms in your yard as a last resort. If nothing, it’ll act as great compost for already existing plants.

You can also try breaking off a piece of mycelium and growing it in agar. The complicated process can be worth a lifetime supply of mushrooms.