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Silicone Heat Guards for Grow Kits
A heat guard for grow kit setups is a silicone mat that sits between a heat mat and the kit, so the warmth reaches the substrate evenly instead of through hot spots at the base. Our reusable silicone heat guard is made for use with Mondo grow kits, Ready-to-Grow Bags and our heat mats, and comes in several colours that all work the same way.
Why a heat mat needs a heat guard
A heat mat does not warm evenly across its surface. Where the heating element runs, the mat gets noticeably warmer, and a kit placed straight on top takes that heat directly into the bottom of the substrate. The base can then run well above 27 °C while a thermometer on the side of the kit still shows a normal reading. Mycelium at the bottom gets stressed or dies, and a weakened kit is more vulnerable to contamination. The heat guard adds a layer that spreads the warmth across the whole base, so the kit warms gently and evenly.
Heat guard or a homemade solution?
| Setup | What happens |
|---|---|
| Kit directly on the heat mat | Hot spots at the base, risk of overheating the mycelium |
| Towel, cardboard or a book | Unpredictable: too much insulation, or damp from the soak water |
| Silicone heat guard | Made for this job, spreads heat evenly, wipes clean and is reusable |
Using and caring for your heat guard
The order is always the same: heat mat at the bottom, heat guard on top of it, then the grow kit or grow bag in the middle of the guard. Make sure the guard covers the warm area of the mat completely, so no part of the kit touches the mat. Then check the temperature at the kit with a thermometer strip and set the controller so it holds 23–25 °C. The step-by-step version is in the Heat Mat & Heat Guard Manual.
Between flushes, wipe the guard with a disinfectant spray from our mist bottles range at the same time you disinfect the lid of the kit. Silicone does not soak up water, so spilled drops from the 150 ml in the bag simply wipe off. The colour is purely a matter of taste; every colour has the same function. If you do not own a mat yet, the Mycelium Heat Mat comes in 5 W and 7 W, and the Mondotub Big and Pro bundles on the grow box page include a heat guard already.
Frequently asked questions
Do I need a heat guard if I use a heat mat?
Yes. Without a heat guard the base of the kit sits directly on the warmest parts of the mat, which can overheat the mycelium. The guard spreads the warmth evenly and is a standard part of every heat mat setup we recommend.
Can I use a towel instead of a silicone heat guard?
It is not a good substitute. A towel insulates unpredictably, can trap too much heat or too little, and gets damp easily from the soak water. A silicone heat guard gives a consistent, clean layer that you can wipe and reuse.
Does the colour of the heat guard matter?
No. All colours are the same silicone heat guard with the same function. Pick the one you like.
Can I use a heat guard without a heat mat?
You can, but it will not warm the kit, because the guard does not produce heat itself. Its job is to sit between a heat mat and the kit. If your room is below 23 °C, you need a heat mat underneath it.
Is the silicone heat guard reusable?
Yes. Wipe it clean and disinfect it between flushes and between kits, and it can be used again and again. Store it flat and dry when you are not using it.
