Can Tortoises Live in a Greenhouse? (Yes, but Do This First)

Finding a good place to keep your tortoise outside can be very difficult. Especially during the cold winter months, when you need a place that is warm and that will keep the wind and snow away from your tortoise. One of the few places that meet these criteria is a greenhouse. So can you keep your tortoise in a greenhouse?

Tortoises can live in a greenhouse during the winter months. During the summer the humidity and temperature in a greenhouse can be dangerously high for a tortoise. You also need to make a basking area in the greenhouse for your tortoise.

Another thing that you should be careful about is what plants or vegetables you have in the greenhouse. There are quite a few common plants and vegetables, like tomatoes and green beans, that are very dangerous for a tortoise. So, let’s take a look at the vegetables and plants that can pose a harm to your tortoise, and then we will talk about temperatures and the basking area.

Vegetables That Are Dangerous to Tortoises

If you have vegetables in the greenhouse, your tortoise will inevitably end up eating some of them. 

Vegetables, while full of vitamins and nutrients, also contain phosphorus. Which inhibits the absorption of calcium, which is responsible for the good health of the shell. Without enough calcium the shell of your tortoise will start to get soft, and develop multiple health problems. So you want to avoid this.

Vegetables have a calcium to phosphorus ratio, this ratio can be 1:1, 2:1, 5:1, 1:2, etc.

A 1:1 ratio means that the amount of calcium is equal, or almost equal to the amount of phosphorus. So a vegetable with this ratio is not that great for tortoises, but it’s not harmful either. But if possible such a vegetable should be avoided.

A 1:2 calcium to phosphorus ratio is really bad, there are not many vegetables with this ratio, so don’t worry too much about them. Just remember that if a vegetable has more potassium than calcium you should keep it away from your tortoise.

A 2:1 ratio is great, and this is what you should be aiming for. If the ratio goes higher it’s ok, but ideally this is the ratio that you are looking for.

Here is a list of some vegetables that contain a high amount of phosphorus, which you should avoid:

• Corn
• Tomatoes
• Asparagus
• Beets
• Peppers
• Pumpkin
• Cauliflower
• Brussels Sprouts
• Carrots
• Broccoli
• Sweet potatoes
• Green Beans
• Squash
• Romaine Lettuce
• Turnips

At the end of the article I will post a long and detailed list with the most common vegetables found in greenhouses and their calcium to phosphorus ratio.

If your tortoise ends up eating a vegetable that has more phosphorus than calcium, there is no problem if it happens very rarely. What’s important is that their overall diet has more calcium than phosphorus.

If you want to know more about tortoises and how you can make sure that they have enough calcium in their diet you can check out this article: Do Tortoises Need Calcium? (Beginners Guide)

Plants That Are Dangerous to Tortoises

Unlike vegetables, plants can have very dangerous immediate effects. So under no circumstance should you keep your tortoise in a greenhouse that as one of those plants in it:

• Amaryllis
• Asparagus Fern
• Avocado Leaves
• Azalea
• Begonia
• Boxwood
• Buttercups
• Calla Lily
• Castor Bean
• Crowfoot
• Daffodil
• Ficus
• Holly
• Iris
• Ivy
• Juniper
• Nightshade Family
• Poinsettia
• Primrose

The effects will differ from plant to plant. Some are simply poisonous, some will irritate the digestive system, some will cause skin irritations, and so on. But in all cases the effect will be bad.

If your tortoise ends up eating one of those plants, you should go to the vet as soon as possible.

Temperature and Humidity

Despite their rough look, tortoises are actually very sensitive to temperature. Like all reptiles, tortoises are cold blooded, which means that they can’t regulate their own body temperature. So they are entirely dependent on the outside temperature.

On average tortoises need a temperature of 75°F (24°C). Most of them will be fine with a difference of a few degrees. But overall that is the temperature that you should be aiming for.

If the temperature gets too high, your tortoise will try to cool itself off by digging holes and hiding in them, or by hiding in other areas with shade where the sun won’t reach them.

If the temperature gets too low, your tortoise will either spend more time basking, since that part of the greenhouse will be warmer. Or it will prepare to brumate, which is similar to hibernation. And it will become less and less active, until the temperatures drop enough for it to be able to brumate.

As for humidity. Tortoises need an average humidity between 50% and 60%, but the exact number differs from species to species.  But for most species, if you keep the humidity between 50 and 60%, everything should be fine.

As for how to control humidity in a greenhouse. There are a lot of things that you can do. Open or close windows, arrange the plants a certain way, use an electric humidifier, adjust the ventilation system, etc.

Now there is one more thing that is left to cover, and that is the basking area.

The Basking Area

Tortoises need to bask for two reasons, to regulate their body temperature and to get vitamin D, which comes from the UVB rays.

UVB rays are naturally produced by the sun, but the glass of the greenhouse stops most of them before they can reach your tortoise, so even if your tortoise gets plenty of sunlight, it doesn’t get all the benefits from it, so you still need a basking area.

Heat bulls and UVB bulbs come with different wattages, 50 watts, 75 watts, 100 watts, and so on. No wattage is better than the other, instead, some wattages are better suited for some setups, than others.  So let’s see which one suits yours.

How to Choose the Best Heat Bulb for Your Tortoise

There is no such thing as a general best wattage, but there is the best wattage for each specific situation. So let’s figure out what is the best wattage for you.

In order to give an answer that will fit your setup and your tortoise, we need to know two things.

The first is what temperature you can expect from a light bulb at certain distances. And second, what tortoise species do you have?

Now, let’s start with the first.

Here is a chart that I made showing what temperature you should expect to achieve using different powered light bulbs at certain distances.

To make this chart I used a laser thermometer and the average temperature of the room was 75°Fahrenheit (24°Celsius), so you might get slightly different results depending on the temperature of your room, but unless the difference is massive the temperature of the basking area should be similar.

As for the bulbs, I’ve been using these bulbs for a few years, but from my experience, all heat bulbs are very similar, so you can use whichever you like the most. But, make sure to avoid mercury vapor bulbs, I will explain shortly why,

Now that you know what temperature to expect from a heat bulb, based on distance and wattage, it’s time to see what temperature you actually need.

Overall most tortoises require a similar temperature range, but if you want to get into detail, they are slightly different. And here is a list of the most common pet tortoises and their ideal basking area temperatures:

How to Choose the Best UVB Bulb for Your Tortoise

When it comes to choosing UVB bulbs things are a little more complicated due to the huge variety of wattages, in which UVB bulbs can be found. And then there is the fact that most manufacturers have a different rating system, and some of them have no instructions at all.

So, for UVB bulbs, I am going to give you the exact distance for a few bulbs that I’ve used before that come from a reputable manufacturer, and I will provide links to Amazon, where you can get them

And in case you have something between the UVB bulb, like a net, or a grill, you want to move the bulb closer by one inch, as anything in between the tortoise and the bulb will reduce the amount of UVB rays.

One more thing to keep in mind is that UVB bulbs will stop producing UVB rays, way before they will stop producing light. On average I would say that a UVB bulb only produces UVB rays for only half of its lifespan. I measured the amount of UVB light produced by the bulbs and noticed that after about 6 months, the amount drops considerably, so I change my light bulbs at around 6 months, and I would advise you to do the same.

Final Thoughts

So, can tortoises live in a greenhouse? Yes they can. But you must first make sure that there are no dangerous plants or vegetables in the greenhouse. And that the temperature and humidity is suitable. And of course you need to make them a basking area.

After you make sure that everything in the greenhouse is right in the greenhouse, you can safely keep your tortoise there all year round.

Here is a list of some of the most common vegetables and their Calcium to Phosphorus ratio:

Hello,

If you enjoy the content that we create, please consider saying a "Thank You!" by leaving a tip.

Every little bit can help us tremendously in continuing to create quality content that helps turtle and tortoise owners around the world.

We really appreciate the kindness and support that you show us!