Can You Reuse Mushroom Grow Kits? (Solved & Explained!)

Mushroom growing kits are one of the quickest and easiest ways to grow mushrooms which – unlike other vegetables – are not truly vegetables and can’t just be grown by planting them in the ground. So, can you reuse mushroom grow kits or are they single use?

Most mushroom kits can be reused at least a few times, yes. They will have a limit, since the food will eventually be depleted by the mushrooms and all used up, but you can usually use them more than once without an issue.

Can You Reuse Mushroom Grow Kits?

Yes, you can usually use mushroom kits several times. The kit will need to be rehydrated and thoroughly saturated with water before you can grow more mushrooms in it, but this is very simple to do.

Don’t try to reuse the kit without replacing the moisture, though. Mushrooms depend heavily on having lots of moisture in their growing conditions, and if you try to grow them in a dry substrate, it won’t work.


How Do You Rehydrate A Mushroom Kit?

You can rehydrate your mushroom kit if you soak it in water for a few hours. You will then need to allow the kit to rest for a few weeks (often between two and three weeks is fine) before you plant more mushrooms in it.

If you skip this rest period, you may find that the mushrooms don’t grow properly, so mark the date and make sure you give it the full amount of time. You should do this every time you reuse your mushroom kit.

How Many Times Can You Use A Mushroom Grow Kit?

This will depend a bit on the kit and the quality of it, but many kits can be reused. The exact number of uses will probably depend on the quantity of the mushrooms you get and the conditions they are grown in.

You will know when the mix has had its full use, because it will start to crumble and it won’t be easy to grow mushrooms in anymore. When this occurs, it will get increasingly difficult to grow mushrooms in it, so you will probably want to give up and get a new kit.

How Long Does A Mushroom Grow Kit Last?

Most mushroom grow kits will last between two months and a year. If you spawn mushrooms every few weeks, allowing for regular breaks, you should get a good few crops within a year. Not all kits will last this long, however, so you may find yours only lasts about six months.

What Should You Do With Used Mushroom Kits?

The best thing to do is reuse them until they won’t grow any more mushrooms. When you have done this, you can simply compost them! They will add some nutrients to a compost heap, and will soon disappear without causing any other issues.

You may even find that your mushroom kit produces you a final flush of mushrooms when it is in your compost heap! This won’t always happen, but it’s a good idea to keep an eye out for a last crop so you can pick them.

Can You Keep A Mushroom Kit Growing?

You can for a while. The substrate that you are growing in will last for ages, providing the mushrooms with enough nutrients to keep cropping multiple times.

Even once the nutrients have been used up, putting your kit somewhere with other sources of nutrients (such as your compost heap) may result in mushrooms continuing to grow, as the mycelium may still be strong and healthy.

Can You “Pause” A Mushroom Kit Between Cycles?

Yes, you can! Both opened and unopened bags of spawn can be stored in the fridge, but you should make sure that they are kept airtight with multiple layers of plastic bags to ensure that the moisture doesn’t dry out of them.

Use Ziploc bags and remove as much air as possible to keep the spawn nice and moist, and be careful to do this every time you put the mushroom kit back into the fridge.

How Long Can You “Pause” A Mushroom Kit For?

It depends on the substrate that has been used for the kit, but you may be able to store it for some time.

If you have got plug spawn, this can be kept for up to six months, which is probably the longest option. It keeps very well in the cold conditions offered by a refrigerator.

If you have bought grain spawn, it will only last for a couple of months at the most, after which it may not be viable any longer.

Sawdust spawn will usually last for several months, but results are slightly more varied with this kind, and you might find that it will fruit even if you keep it in the fridge. If this happens, just harvest the mushrooms, minimize the air, and store it in the fridge again.

What Is Spent Mushroom Substrate?

This is the term that is used for the substrate that is left after all the mushrooms have finished growing and there will be no further crops. It means that the substrate will do nothing further, and all its nutrients have been used up.

You may also see this called “spent mushroom compost,” which means the same thing.

What Can I Do With Spent Mushroom Substrate?

You can’t use it to grow mushrooms anymore, so what else can you do with it? Many people choose to add it to their gardens, but be aware that this has some problems.

The substrate tends to be high in salt, and high in nitrogen. Both of these can be bad for the garden when added in quantity, so make sure you aren’t using too much spent mushroom compost on your plants.

If you want to add this to the garden, it’s a good idea to try and rinse the salt out first. Wash the mixture through with a hose for a good ten minutes or so, and then drain the water away. This should rinse the salts to the bottom and away, although some salt will remain.