Possible challenges and solutions for mushroom grow kits

Growing mushrooms at home with a JCB Gourmet Mushrooms grow kit can be a simple activity that rewards you with huge clusters of yummy food. It will also always be a learning experience that will help you grow mushrooms the next time.

We have dealt with a lot of trial and error as we grow mushrooms in our facility. We are learning what works and doesn’t work with mushrooms, and we are now sharing some tips with you in case you are having a slightly tougher time with your grow kit.

Check out: Frequently asked questions

Temperature is too hot

When you have trouble keeping the temperature within the ideal range, it becomes less likely that mushrooms grow. If they do, it may be in smaller clusters or different shapes. For example, the photo of the Lion's Mane on the right shows it has a branchy shape rather than looking like a brain or pom pom with cascading spines. This can happen with warmer temperatures or too much light.

Solution: There are mushrooms that can handle warmer temperatures, such as the Italian Oyster, Reishi, Chestnut mushroom and a couple more (check out the link below for the full list). If you have a basement or somewhere without windows, place your grow kit there and turn off the light when you aren’t in that location. Mushrooms need a bit of light to orient them during the growing process, but you can keep the light off afterwards to keep the temperature lower.

Check out: How to grow mushrooms in warmer indoor temperatures

Not enough humidity

Humidity is quite important for mushrooms. If there isn’t enough humidity, the mushrooms may slow down and/or stop growing. It would be like if we don’t hydrate ourselves on a hot day or when we’re exercising – we begin to slow down and not feel too good.

Solution: You should mist more often. Misting too much at once may cause the mushrooms or block to get softer, but if you mist about 15 to 20 pumps each time, that should do the trick. For example, if you are only misting three times a day, try five times a day. You could also try placing the block somewhere without as much sunlight, such as the basement.

You could try using a small diffuser without any trace of essential oils or scents. Stick the diffuser under the humidity tent and set a timer that lets it turn on and off in intervals, if possible.

Click here to grow mushrooms like the Italian Oyster at home.


This is sometimes difficult to avoid. Luckily, most of the contamination happens at our facility. We hand-select the grow kits that developed mycelium and are ready to grow mushrooms. The contamination is more likely to happen before that stage as fungi search for food in the growing block.

However, you may see green, orange, or black moulds that appear. This can happen if the block is too wet due to having too much water on the block instead of on the humidity tent, or if the temperature is too high.

We tend to see a slightly higher risk of contamination in Chestnut and Shiitake mushrooms, but they taste so well that as long as you observe them closely when misting, they are kits worth trying.

Solution: If it is orange or black mould, you will want to move it outside and dispose of it as soon as you can. If this is before your first harvest, please take a picture and contact us.

If it is green mould, you can try to remove it from the block with a knife before it spreads. If it has spread throughout the block – which may happen the longer you have the kit – the mushrooms are done growing and you can use the block as compost.

Not enough oxygen (or too much airflow)

We had this problem as we started to increase our production in 2021 and had hundreds of mushroom blocks sitting against each other on rows and shelves. Mushrooms breathe in oxygen and release carbon dioxide (CO2) just like humans. If your grow kit is not getting enough air circulation, the mushrooms will have a different shape. The Oyster mushrooms will have smaller caps and thinner stems. If there is too much air circulation like if you have a fan pointed at your block, it will blow away the humidity and dry out the mushrooms.

Solution: If you have your grow kit in a small, enclosed space, make sure you have a way to allow for fresh air exchange. Otherwise, ensure that the block is away from a fan to avoid drying out the block.

Waiting too long to harvest

This is something to be aware of ahead of time. The mushrooms grow so quickly that they can be almost ready to harvest in the morning, perfect in the evening, and then not as great the next day.

That's also why it's important to mist multiple times a day, because you get to see the grow kit and harvest a side before it's peaked in quality. For all the grow kits except for Shiitake and Reishi, you can simply grab the cluster at the base and pull up with your hands. They can go in a bag and in the fridge right after that.

You may be too late to harvest them and they begin to spoil. It happens to the best of us. You may have caught it in time that it is still good to eat but the shelf life is shorter. It is usually up to you to decide, but if the caps have curled up completely on Oyster mushrooms or if the Pink Oysters turn yellow, you are probably better off dehydrating the mushrooms or just trying again with another harvest.

If you are still facing challenges and aren't quite sure what the issue is, you can always take a picture of your setup and contact us at jcbgourmetmushrooms@gmail.com. But now you know there can be quick fixes to your grow kit setup to give you a better chance for your following harvests to grow happy and healthy. You are only a few clicks away from a grow kit on the way by getting this far.

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