As winter approaches, and the temperature drops, its not uncommon for that formerly toasty reptile cage to start developing quite a chill.
The heater that has done its job perfectly for months on end finally starts to struggle to deal with the cold. All too soon, if you’re not careful, the cage temperature drops dangerously low, and action needs to be taken.
The Problem with Heat Mats
Most invertebrate keepers, and even many snake owners, use low-wattage heat mats to warm their vivariums. While these are a safe, low-cost and generally effective way of providing artificial heat, they’re not without their weaknesses. The main problem being that they only produce a gentle warmth.
While your reptile cage may sit comfortably at 25’C during September and October, by the time winter sets in properly its not uncommon to find the ambient temperature in the cage dropping. This is especially so if you’re out at work or school during the day, as it’s unlikely you’ll have your household heating on to take the edge off things.
So what can be done?
Over the years I’ve lived in some very cold properties – more than one of which didn’t even have central heating. In that time I’ve had to test and develop a range of techniques for significantly increasing the temperature in my vivariums, especially those with plenty of ventilation which can let the cold air in.
Here are my tips for keeping your vivarium warmer, if your current heater isn’t doing it’s job effectively enough…
Upgrade Your Vivarium Heater
If your reptile heat mat isn’t raising the tank temperature up enough then the first obvious solution is to invest in a more powerful heater. The obvious question then becomes – what’s more powerful than a heat mat?
Putting aside most lizards for a moment – who should have a high-powered basking lamp at all times anyway – what we really need is a source of underfloor heating for your tarantulas, mantids or snakes. This can then be used just as your heat mat is right now, but simply gives out rather more warmth.
In the 20-odd years I’ve been keeping reptiles and invertebrates I’ve experimented with a range of options, but possibly the most effective has been soil-warming cables.
These are long, waterproof wires, designed for greenhouse gardeners. The theory is that these cables can be buried in the earth of your beds, thus gently warming the soil. This encourages quicker germination and more vigorous growth.
But the same piece of equipment can be used quite effectively in the home by reptile keepers.
The heaters come in a range of different lengths, so you can choose an option which suits the number of cages you have to heat. The cable can then be run along behind or under each of your reptile cages.
I have found that these provide considerably more heat than heat mats, so are an ideal solution for cold winters. Personally I use tape like this to fix the cable down, otherwise every time you move your vivariums you’ll disturb the cabling.
IMPORTANT NOTE: As soil warming cables can get very warm (I’ve heated ball pythons to 30’C using them without issue) it is essential that they are used with a suitable thermostat. This ensures that your precious reptiles won’t overheat, even if the ambient temperature in the room starts to rise.
Add a Second Heater
Just because your heat mat isn’t quite getting the temperature high enough doesn’t necessarily mean that you need to replace it altogether. A second option is to add a second source of heating to the mix.
This is often the solution I use with my Exo Terra terrariums, which with their all-glass construction and well-ventilated lids, don’t hold the heat as well as a wooden vivarium might.
In the case of my Exo Terras I use the special tank lids that can be purchased separately, and place a low-powered heat bulb like this one into it. I find a 25W bulb is more than effective even in the coldest weather.
This heat bulb is then controlled in two manners. Firstly, it is placed on a timer, so I don’t need to remember to turn it on. Most of mine are scheduled to be on between 10am and 6pm. Secondly, as with soil warming cables, be sure to use an effective thermostat to control the vivarium temperature.
Combining my hat mats with heating lamps allows me to produce almost any temperature that my reptiles need with the minimum of fuss each winter.
Use a Reflector
Hat mats give out warmth from both sides – even though only one is placed next to the vivarium. In many cases, therefore, you’ll find that you’re heating the shelf or table that the tank is on as effectively as the vivarium itself.
Using a reflector behind or underneath the heat mat can therefore help to reflect more of this beneficial heat into your vivarium.
I use two different options here and have found them equally effective. On the one had I use polystyrene tiles for under-tank heaters. I just place down a few tiles, put the heater ontop, and then place the vivarium over this.
For heaters attached to the sides of vivariums I’ve had excellent results with self-adhesive cork tiles, which are just as insulative but look visibly more attractive stuck to the side of the tank.
Insulate Your Vivarium
While wooden vivariums tend to retain their heat well (and so I my general recommendation for most reptiles), invertebrate keepers using glass or plastic containers may struggle a little more.
We’ve already discussed the possibility of using cork or polystyrene as a reflector, but these can also be used to better-insulate cages.
I know of several keepers who use a hot glue gun to attach cork tiles to the outside walls of their glass tanks, leaving just the front area free of insulation. They report that this process can be very effective indeed for keeping in heat during the winter, and so keeping the cage warmer than before.
Reduce Ventilation
Ventilation is a touchy subject among exotic pet keepers. After all, everyone knows that ventilation is important to prevent mould build-up, but can reducing this ventilation in a reptile cage help to boost it’s temperature?
I would argue almost certainly that the answer is “yes”. For example, if you’re using an Exo Terra with a mesh grill lid, then popping one or two of the tank covers on, or adding a piece of clear plastic over part of the lid can be a highly effective way to increase the temperature in the cage.
If you’re going to down this route, however, be sure to keep a closer eye on the cage than normal, and never block off all ventilation.
Heat the Room
The last option, as used by some serious reptile keepers, is to heat not just your reptile vivariums, but also the room that they’re placed in. Some people, for example, will keep the door to their “reptile room” closed, and leave an oil-filled radiator or suchlike on low power throughout the day.
The radiator doesn’t need to be on full blast – just enough to raise the ambient room temperature to some 16-20’C is normally more than enough to let your heat mat do the rest of the job.
Whichever option you select, it’s very important that you take action as quickly as possible. A tarantula, mantis or snake that is kept far too cold for too long is at risk of developing health issues and/or going off food. In extreme situations the impact could even be fatal.
If you’ve noticed that your pet seems sluggish, or that your thermometer is reporting a far lower vivarium temperature than you would like, it is wise to get any necessary equipment ordered now so that you can resolve the issue as soon as possible.
Photos c/o highlander411 & © Axel Naud 
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I have a question about keeping my snake tank warm. This is a tank got as a gift, and I need to put a screen lid on (I’m covering part of it to try to keep air in the tank). How do I make sure the tank doesn’t get cold at night/ during the summer when the AC is functioning outside the tank (I don’t control it)? I was thinking during the day having a heat lamp and at night (especially in winter) having a heat mat to provide gentle heat to keep the temperature safe for my snake. Is this a safe method? Would I hurt my snake? I don’t want to hurt it when I finally get one. What should I do?
Hi Angela – Yes I think the method you have suggested would work fine. I would strongly suggest that you use a thermostat to control the temperatures of these heaters to avoid overheating. Additionally, be sure that your snake can’t come into direct contact with either heater, as you don’t want to risk burns.
If I put soil- arming cables in my substrate, can’t my sanke burrow and urn itself on it? I live in NYC and winter days can go below freezing. I want to keep my snake warm, but don’t want to burn it or anything. My house doesn’t have a centralized heating system. Also, my apartment has poor ventilation because we have so many windows.
Hi Mohammed – I use the soil warming cable *under* the vivarium. This works if it is glass or plastic, but not wood. In this way your snake won’t come into contact with it. An additional option I’ve tried is to better insulate the cage in the winter months, which helps to keep the heat in.
Which soil warming cable should I use? I found one on Amazon, but it says it does not work well with thermostats?
I’m in the UK so the soil warming cable I bought may not be available to you. Over the years I’ve used several, however, and found that they all seem to give out quite a “gentle” heat if used properly. All the same, I would always advise the use of a thermostat for safety. If the model you found doesn’t work well with one then I’d consider looking for another model to keep your pets safe.
Hi there, I noticed you mentioned getting a 25 watt heating bulb for extra heat, but do you have any particular brands or types of light that you use? Most of the reptile-specific ones are of higher wattages or seem to have unreliable reviews.
And when you mention an exo terra lid, do you mean one of the dome lights, or a light fixture? Any specific model you think works best?
I want to get the air temperature on one side of my young western hognose’s tank up to 92 degrees or so during the day, but the heat pad and UVB light (I know snakes don’t strictly need one, but recent studies indicates they do benefit from UVB) only gets it to about 84 degrees or so (its 92 under the substrate, where the thermostat sensor is, but I’d rather the snake not have to burrow to seek ideal warmth, since she seems to like to cruise the surface during the day). The tank is an exo terra large low (36 inches, by 18 inches, by 12 inches tall). Since the tank is pretty short I worry about getting a light that is too bright and/or hot. Perhaps a low wattage ceramic heat emitter instead?
Many thanks for any help!
Hi Jonathan! I use the Exo Terra canopy for many of my reptiles.
By the sounds of it a ceramic bulb (with a suitable thermostat) could work well in your situation. I have a number of 75 watt ceramics, attached to a Habistat Dimming Thermometers and they work well with Exo Terras. You can fit the bulb into a ceramic bulb holder/reflector (mine is from Exo Terra) and then just place it on the mesh of the lid. Just be sure to monitor that temperature to ensure it’s suitable.