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Updated ! How to Use a Thermo Mat Without Killing Your Grow Kit
Publié sous: Growing & Cultivation
A simple guide to keeping your magic mushrooms at the perfect temperature — even when it's cold outside.
You want big, healthy mushrooms. A thermo heating mat can help you get them — especially in winter. But if you use the mat the wrong way, it can destroy your grow kit instead of helping it.
This guide shows you exactly how to use your thermo mat the right way, step by step.
⚠️ The #1 mistake we see every day? Growers placing their kit directly on the mat. Keep reading to learn why that's a problem — and how to fix it.
Why Do You Need a Thermo Mat?
Magic mushroom grow kits need a temperature between 20–28°C to grow well. Around 23°C is the sweet spot. But what if your room is colder than 20°C? That's when a thermo mat helps. It gives your kit the extra warmth it needs so you can grow all year round.
Watch this short video to see how thermo mats work:
This video was made a while ago. The basics are still correct, but we've learned extra tips since then. Read on for the full updated guide.
Your 4-Step Plan
Follow these four simple steps to protect your grow kit and get the best harvest.
1
Check the Room Temperature
Check the Room Temperature
Before you plug in the mat, check how warm your room is. Is it between 20–24°C? Then you don't need the mat at all — your kit will grow fine on its own. Only use the mat when the room stays below 20°C.
Save electricity! If your room is warm enough, keep the mat unplugged. Only turn it on when the temperature drops below 20°C.
2
Create Space Between the Mat and the Kit
Create Space Between the Mat and the Kit
Never put your grow kit directly on the mat. Most thermo mats heat to 30–40°C. If that heat goes straight into the substrate, it will cook your mycelium.
Place something between the mat and the kit to create a gap. Good options: chopsticks, pencils, a small wire rack, or a folded towel. This gap lets the heat spread gently instead of burning the bottom. We call this "diffusion."
3
More Space Is Better
More Space Is Better
A small gap is good. A bigger gap is better. Two pencils alone may not be enough. Use a small wire rack or stack several items so plenty of air can flow between the mat and the kit.
4
Watch the Temperature
Watch the Temperature
Keep an eye on how warm the area around your kit gets. Use a digital hygrometer and thermometer to measure the exact temperature near your kit. If it reads above 28°C, there is not enough space between the mat and the kit. Adjust until the warmth is gentle — not hot.
Too much heat kills mycelium — and dead mycelium cannot grow back. If your kit overheats, you will not get any mushrooms from it. A thermometer takes the guessing out so you always know the exact temperature.
Using a FreshMushrooms grow kit? FreshMushrooms recommends using the thermo mat only during the first few days of cultivation. After that, your kit usually doesn't need the extra heat. They also suggest placing the mushroom cake upright and on its side for the best results.
What Happens When It Goes Wrong
These photos show real grow kits that were placed directly on a thermo mat with no space for air. The substrate overheated and the kits stopped growing:
Almost Right — But Not Enough Space
These growers used some diffusion, but the gap wasn't big enough. The kits needed more room for air to move:
And here's what a proper setup looks like — with plenty of space:
You're Ready to Grow
That's all there is to it. Use your mat when it's cold, always create space for airflow, and keep the substrate moist. Your mushrooms will grow beautifully. ?
Want to learn more? Read our full guide on How to Grow Magic Mushrooms at Home. Already harvested? Learn how to dry and store your magic mushrooms the right way.
Ready to grow all year? Get your Thermo Mat here!
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