Many plants enjoy very high humidity, and if you want to grow these beauties indoors, you may have a problem. How can you keep one of these delicate little things alive without breaking the bank?

Venus flytrap

Lots of people like to experiment with carnivorous plants like the Venus flytrap, but these beauties need lots of humidity and light to grow – making them the perfect plant for bottle terrariums.

Photo Credit: Barry Rice/sarracenia.com

Butterwart terrarium

Be sure to use a clear plastic bottle so your plants, like this hybrid butterwort (Pinguicula), get plenty of light.

Photo Credit: Barry Rice/sarracenia.com

Sundew terrarium

To provide the humidity that plants like sundew (Drosera capensis) need, they should sit in about an inch of water.

Photo Credit: Barry Rice/sarracenia.com

Carnivorous plants (my beloved specialty) are a perfect example of these tricky humidity lovers. But unless you’re related to a swamp monster and you like to have water dripping down your walls, your house is far too arid for them. And if you’ve got air conditioning, forget it! That cooling system sucks the water right out of the air.

So what should you do if you want to try your luck with a Venus flytrap, sundew or pitcher plant? First, forget the advice of growing them in the bathroom. The pebbled glass and curtains ensure that bathrooms are invariably too gloomy for sun-loving carnivorous plants. Also, putting a plant in a tray of water doesn’t help much if the air circulation in your house carries off the little bit of humidity the tray provides.

You see, fanatical carnivorous plants specialists grow their fabulous specimens in large, complicated terrariums equipped with lights, fans and a host of other complex modifications. These easily cost a few hundred dollars – not as expensive as a greenhouse, but still too pricey for a casual grower.

The solution? Simple bottle terrariums – the cheapest terrariums possible. And they’re actually perfect if you’re casually experimenting with carnivorous plants! Even better: These easy-to-make terrariums are a great family project, and they’ll give you a taste of what it’s like to have a carnivorous plant in the house.

First, you need a big empty plastic beverage bottle, at least 1 liter in size. Make sure it’s clear – not tinted. Peel off the label, and clean it up as much as you can. Next, with a sturdy pair of shears or a sharp knife, cut off the bottom of the bottle. (This step is best saved for an adult.)

Next, find a dish that can hold about an inch of water and can fit inside the bottle or that the bottle can easily sit inside. Set your carnivorous plant in the dish, add about half an inch of water, and drop the bottle over the plant. Instant terrarium!

The beauty of a bottle terrarium is that it’s easily customizable. If you want to increase ventilation, remove the cap to the bottle, or even cut some holes near the top.

The truth is that carnivorous plants can be hard to grow. But a bottle terrarium can give you a reasonably good shot at success. If you’re unsuccessful or decide you don’t love carnivorous plants (harrumph!), you haven’t spent too much money on your experiment. But you just might decide that carnivorous plants are your new love in life.

In fact, I’m guessing that one bottle terrarium won’t be enough for you. Soon you’ll have another…and then another…and another. And when your windowsill starts to look like the storage depot for a recycling center, then you’ll know: It’s time to think about that big terrarium after all!