Carnivorous Plant Primer
Joe Gadbois, January 19, 2025

Happy New Year! I hope you all had a fun and relaxing holiday season. There are many things that we can do in winter to occupy our minds and scratch the gardening itch, and growing indoor plants is, in my opinion, a must for plant lovers. In the realm of indoor plants, carnivorous plants are one of the most exciting and intriguing topics, and that is the focus of this week’s article.
Carnivorous plants are not exclusive to indoor gardening; in fact, there are species that are native to Alberta and can be grown outdoors (the purple pitcher plant, Sarracenia purpurea, is native to Alberta and most of Canada and is the provincial floral emblem of Newfoundland & Labrador). But tropical and warm-temperate species are the most commonly available and are arguably the most spectacular. I found my way to this topic as a teenager, as it is a natural place for orchid lovers to wander to. Many carnivorous plants, or “carnivores” as hobbyists refer to them, make great companion plants for orchids and other indoor plants. They are also an obvious choice for terrariums, which is why reptile and amphibian enthusiasts often stumble into this topic as well. It’s an interesting place where people from all walks of life meet (as gardening so often is) – it attracts any kind of person that appreciates the weird and wonderful side of nature. It’s also a great gateway for kids to get into plants, although the care requirements may be a little involved for super youngsters, who will need help from their parents!

So, why do carnivorous plants exist in the first place? Carnivores come from habitats where soil nutrients are scarce, such as bogs, and their insect eating capabilities are an adaptation that allows them to capture prey for nutrients instead of absorbing them from the soil as other plants do. There are several different methods that plants have developed for this purpose, including sticky leaves (i.e. a flypaper trap), pitfall traps, the clamshell trap employed by the infamous Venus flytrap, and even underwater chambers that suck aquatic prey in and trap them.
This group of plants is not necessarily the best for someone who has never attempted to grow a plant before, but they range from being relatively easy to care for to very difficult, with all having specific needs that must be met. I’d like to touch on some of the more accessible ones you might like to get your feet wet with, and if you are intrigued by what you read here today, I highly recommend you seek out books and online resources to learn more about them!
Butterwort (Pinguicula spp.)

The first type of carnivorous plant I can recommend are the butterworts. Called “pings” by hobbyists, there is quite a range of them, and they are found in many different habitats, including here in Alberta. Tropical species and hybrids are the best choices for indoor growing, as they don’t require a dormant period. They form a low rosette of fleshy leaves which are covered in a slippery coating that traps insects like flypaper. Once trapped, the insect is slowly digested by the plant. These have been used as a natural control for fungus gnats in greenhouses and homes for many years. Many types are adaptable to household conditions, but they do best in the humidity of a terrarium. Bright light is required, such as an east or west window, or under grow lights. Some varieties will blush pink in strong light, and all produce beautiful flowers which can appear at any time of year. Grow in well-drained potting mix that is fertilizer-free, such as half peat and half perlite, and always keep the soil damp; some growers keep the pots standing in ¼ inch of water. Use rain, distilled, or reverse osmosis water; don’t use tap water or fertilizer. Most carnivorous plants are very sensitive to minerals in the soil or water.
Venus Flytrap (Dionaea muscipula)

The infamous Venus flytrap is only found naturally in one part of the world: the Carolinas of the United States. This means that it is not a tropical, but rather a warm-temperate, plant. It requires a cold winter dormancy, which is one of the more tedious parts of its care in a part of the world where the winters are too cold to keep it outside. But we’ll get to that. Venus flytraps are famous for their clamshell-like traps (modified leaves) which sit open with an attractive red or pink colour on the inside, secreting tiny amounts of honeydew to attract prey. Trigger hairs on the inner surface of the traps will cause the trap to snap shut in a fraction of a second if touched twice within a couple seconds. The trigger hairs must be continually touched over the next few minutes for the trap to fully close over its victim; this is to ensure energy isn’t wasted trying to digest a false catch such as a raindrop. This also means that live food must be fed to the plant, or the trap will simply reopen without digesting it. The best way to do this is to buy or capture live insects yourself, then place them in the freezer for a minute so they fall asleep. Place the sleeping insect on a trap and trigger it shut. The insect will soon awaken and begin stirring, causing the trap to fully enclose and begin digesting it. A couple days later, the trap will reopen to reveal the undigestible remains of its meal. Of course, when it’s warm outside, a less creepy way of feeding the plant is simply to place it outside for a few hours and let it catch its own meals.

Plants can easily be overfed, and the traps are only designed to catch a few meals each, so don’t be surprised if recently fed traps soon die off. You only need to feed once a month or so while the plant is actively growing. Never feed any carnivorous plant any food other than insects, and feed flytraps insects that are smaller than the trap. While the typical form of the Venus flytrap is easy to find, there are some fun “mutant” cultivars out there as well, such as ‘Dente’ and ‘Red Dragon’. They produce nondescript flowers which are normally cut off before they develop unless seed is desired (growing from seed takes some patience but can be done).
Because of their high humidity requirements, it’s best to keep these in a terrarium or some kind of enclosure. Full sun is required, but as they can cook in a terrarium exposed to full sun, I recommend using good LED grow lights instead. As with butterworts, keep the soil damp, using pure water only (no tap water or fertilizer). As for the winter dormancy, you can stick the plant in the crisper drawer of the fridge, in a Ziplock bag, from November to February (3 months total), and check it every couple of weeks to make sure it doesn’t dry out or mold over. You will find the plant will stop producing traps while dormant, which is normal. Traps will reappear once you bring the plant out into the warmth again. If you never provide this dormancy, the plant may survive for a couple years but will eventually die.
Tropical Pitcher Plant (Nepenthes spp.)

Nepenthes (pronounced nep-EN-theez) are tropical vines that produce their traps, called pitchers, on the ends of tendrils that extend from the central vein of each leaf. These pitchers can have some spectacular and unusual colours and can range from a few inches to a couple feet in length, depending on the species or hybrid. Some varieties are monstrous when mature and require a greenhouse or sunroom, while others can be grown in a small terrarium or even a windowsill. Most plants offered at garden centres are young and not yet displaying their mature pitchers, so Google photos of the species/hybrid to see what it will look like.
The pitchers themselves attract insects with their colours, and sometimes also with honeydew secreted near the rim. Once an insect lands on the rim, they will find it to be very slippery and will fall into the pool of liquid below. Downward pointing hairs prevent escape. The drowned insect will be digested by the plant.
Nepenthes can be grown in a variety of potting mixes, but as with other carnivores they should be free draining. I like New Zealand sphagnum moss mixed with perlite. Keep the potting mix moist, but not soggy wet, and use pure water (not tap water). I have heard of some growers using very dilute fertilizer on the roots occasionally, and more commonly, people will put dilute liquid fertilizer or slow-release pellets into the pitchers to feed. The more traditional method is to simply drop a couple bloodworms in. Once a month feeding is plenty; I usually just feed a couple pitchers, not all of them. More mature plants can take and benefit from more feeding. Most Nepenthes need high humidity, or they will stop developing pitchers, but sometimes they can adapt to windowsill culture. I have always kept them in terrariums, and there are smaller varieties that work well for this. Bright, indirect light is required.
American Pitcher Plant (Sarracenia spp.)

Pitcher plants found across temperate North America belong to this group, and they are quite different from Nepenthes. The colourful leaves are rolled into a tube that ends in a flared trumpet, and these pitchers hold water and digestive fluid. The trap works much the same way as Nepenthes. Pitcher plants kept outdoors in the summer will be filled to the top with wasps by the end of the season! As bog plants, they grow best with their pots sitting in shallow water. They don’t have high humidity requirements, but they do need full sun for the best colouration, and they do require a cold winter dormancy (see the Venus flytrap section). Like with the flytraps, plants will not survive in the long term without this dormancy. In addition to the showy leaves, American pitcher plants produce beautiful, otherworldly flowers in the spring.
Sundew (Drosera spp.)

The sundew is so named because of the droplets of sticky material that are found at the ends of hundreds of tiny cilia that cover the leaves. These glistening droplets both attract and capture insects. Leaves that are digesting a meal will often fold over the trapped prey. These beautiful killers appreciate bright light to full sun and high humidity, so also make good candidates for terrariums. They come in a number of shapes and sizes, but most often are a small plant made up of a low rosette of leaves. The overall care is very similar to that for butterworts.