Absolute Surefire Steps to Kill Your Venus Flytrap: Step 4

Curious about the context? Check out the introduction.

Some of the content in this series appeared, in much shorter form, in Gothic Beauty magazine.

Step 4: Keep your flytrap in a terrarium.

I have a lot of reasons for hyping fellow carnivorous plant sellers, besides the idea that we’re all in this together. I view Jacob Farin and Jeff Dallas of Sarracenia Northwest as the crazy cousins I never had (well, I have crazy cousins, but not horticulturally inclined crazy cousins), and I enthusiastically turn friends and cohorts in the direction of northwest Oregon when Jacob and Jeff host one of their biannual open houses. This isn’t just because they know their plants and obviously love them. It’s because they’re constantly challenging me. In my old age, I’ve become more convinced than ever that it’s better to be correct than to be right, and they’ve taught me too many times to shut up, listen, and make sure that any questions I ask or comments I make weren’t already answered a week ago. (They also have better stories. I only have to worry about treerats digging up the dragonfruit and geckos hiding in the pitcher plants. They get Pacific treefrogs laying eggs in their aquatic bladderwort tanks and piglets sneaking through the fence from their neighbor’s lot and playing in their lot. The only way I’m ever going to top this is by getting that crocodile monitor after all.)

Anyway, the Sarracenia Northwest tagline is “No terrariums. No myths. No nonsense.” It’s succinct and accurate, and one of the reasons why Jacob and I may be found by palaeontologists 90 million years from now, still locked in combat like the Mongolian fighting dinosaurs. It’s not that he’s wrong. He’s just lucky in that he and Jeff live in a locale where humidity levels aren’t so obscenely low.

One of Jacob’s tenets is that most carnivorous plants can and should be grown outside, in full sun, just the way they do in the wild. He also posits that most carnivores are much tougher than most people assume, and that most adapt to outdoor life much better than expected. He and Jeff offer living proof at their open houses, with growing pools just overloaded with big, bright, sparkly Sarracenia that make my guts ache with jealousy to look at them. Flytraps, bladderworts, and even their beloved Darlingtonia cobra plants…all outside, or maybe under fabric covers if the plant is particularly sensitive to strong summer sun.

To give you an idea on their commitment to researching proper growing traditions, they went into the wild to visit feral stands of Darlingtonia. Tourists may know of the Darlingtonia State Natural Site southwest of Portland, but Darlingtonia californica can be found among seeps throughout the mountains of Oregon, Washington State, northern California, and parts of British Columbia. Darlingtonia is one of the big El Dorados in the carnivorous plant field, having a reputation for being particularly temperamental and likely to die if you look at it cross-eyed. In fact, one of the absolutes that was taught to most carnivore enthusiasts, myself included, is that they can’t handle heat for any length of time. Jacob and Jeff decided to challenge this, taking temperature measurements in prime Darlingtonia habitat and showing that Darlingtonia can handle Dallas-like daytime temperatures in daylight hours with aplomb. (The secret to raising Darlingtonia is that it’s technically an alpine plant, and that it grows in seeps in the mountains fed by snow melt. The assumption was that it needed cool water on its roots at all times: the real issue is how cool the area gets at night. In North Texas, that means lots and lots of air conditioning, because it depends upon the steep temperature drops in the mountains at night, even during the summer.)

This has led to many friendly arguments about whether terraria should ever be used for carnivores. Jacob in emphatic that terraria aren’t necessary, and that he has customers who raise bog gardens in the desert and get great results. I respond that as much as I agree with him anywhere else, some carnivores can only survive in Dallas in an enclosed container. Not only do we receive almost twice as much sunlight as Sarracenia Northwest gets, due to the SN nursery being above the 45th Parallel North, but we also have a dessicating south wind that stops only between October and March. Even on good years for plant-raising, the area regularly drops below 50 percent relative humidity. In bad ones, such as this year, Dallas has lower relative humidity than Phoenix.

Now, you may ask yourself “What does this have to do with the price of cheese?” It’s time for another digression, and a short one this time. Back in 1985, I picked up a 29-gallon aquarium at a garage sale, and promptly drove everyone around me insane with my sudden passion for freshwater tropical fish. While co-workers were sneaking home to read Hustler before their wives and girlfriends caught them, I was sneaking home with the latest copy of Tropical Fish Hobbyist before my roommates knew what I was planning. In the process of learning just enough to be dangerous (and this included keeping, for a very short time in Wisconsin, a red-bellied piranha named “Bub” that would come to the surface to get his nose rubbed), I noted that different authorities gave different advice about the same fish, sometimes in the same book or magazine. That’s when the owner of the sadly defunct shop Neenah Tropical told me “You should never trust the books, because the fish don’t read.”

That’s absolutely true for carnivorous plants, as well. Always take my or anybody else’s advice on keeping carnivorous plants with a healthy skepticism born of actual knowledge. Those of us with expertise will try our absolute best to help, but there’s always the odd exception. If you’re smart, you’ll accept the unique conditions and circumstances in your area that allow success when everyone else falls on their faces. For years, I was able to keep a batch of Darlingtonia raised from seed alive and healthy in Dallas, and I didn’t smirk about how I had special understanding or superpowers. Instead, I stood back and exclaimed in surprise and delight that I’d somehow beaten the odds. And when this kidney stone of a previous summer took them away from me, I took it as an object lesson.

And here’s where I have my very friendly dispute with Jacob and Jeff. I don’t dispute that Venus flytraps are best kept outside. At times, though, they need a touch of help.

In my own experience, I’ve discovered that flytraps grow best when the relative humidity around them stays, day and night, above at least 60 percent. When the humidity goes below 50 percent and the temperatures go above 95 degrees F (35 degrees C), they tend to produce small or nonfunctional traps, and won’t produce new ones until either humidity jumps or temperatures drop. When the temperatures stay this high and the humidity drops below 30 percent, which it did quite regularly in North Texas last summer, the plants simply can’t handle the strain and they die. It doesn’t happen right away, and they can recuperate if conditions improve when they start to fade.

Since a typical Wardian case offers that sort of control, the automatic response to this sort of humidity fluctuation is to put flytraps into a terrarium of some sort. As understandable as this is, this is also dangerous for a flytrap. What I’ve discovered the hard way is that flytraps not only require a lot of sun (at least six to eight hours of direct sun) and a lot of humidity, but they also require a LOT of air circulation. This is why Jacob and Jeff recommend raising flytraps outdoors, where they can get the air circulation they need. Put one in a standard terrarium, and the combination of stagnant air and decreased light intensity are doubly lethal.

A second consideration: even if your flytrap does well during the summer, remember that it’s going to need a winter dormancy period. This leaves you with one of two options. You can put the terrarium outside during the winter, which removes any opportunity to enjoy it during the season where you’ll need a touch of green the most, and risks its being damaged by cold or ice. Alternately, you can remove the flytrap and put it into artificial dormancy in a refrigerator, and then spend the winter looking at the hole in the terrarium where the flytrap used to be. Instead, you might be better off enjoying a tropical carnivore such as a tropical sundew: it may slow down over the winter, but it won’t actually require a full dormancy.

A third factor to consider against a standard terrarium: since the air circulation is so poor in most smaller, seemingly flytrap-friendly terraria, putting one in direct sun is a great way to produce Venus flytrap pottage. Terraria, Wardian cases, greenhouses, and just about any other enclosed space can be used to demonstrate the square-cube law. The smaller the volume, the larger the surface area in proportion to that volume. Put a 100-foot greenhouse in the sun as a two-cup terrarium, and the terrarium reaches killing temperatures much faster.

At this point, you again have two options. You could fit your Wardian case with a solar-powered fan, thereby taking care of the immediate air circulation issue. This, though, does nothing about the dormancy situation. Or, or, you could try a container that helps simulate the best conditions for best health for a flytrap. I’ve discovered that large glass bowls, such as very large brandy snifters or even goldfish bowls, tend to work well in combating Dallas-level low humidity. The container can be put in full sun, where excess heat escapes out the top. Humid air is heavier than dry air, so the humidity stays around the flytrap. Best of all, it can be left outside all year, only pulling it under cover when there’s a risk of snow or ice.

I’d be lying if I didn’t say that there was one more catch. This catch is that while flytraps like moist conditions, they cannot handle standing in water for any appreciable length of time. With that in mind, if you try a large bowl, go for one that’s strong enough to handle the peat/sand mix that’s required for flytraps. Again, many experts recommend against using perlite around flytraps under any circumstances, but I’ve found a layer about one inch (2.54 cm) on the bottom, followed by about four inches (10.16 cm)of equal parts milled sphagnum peat moss and high-quality silica sand, works best. Dress the top with long-fiber sphagnum, wet everything so that it’s moist but not soggy, and plant the flytrap on top. Under most circumstances, flytraps in this sort of enclosure seem to do much better during dry summers than unprotected flytraps, and MUCH better than ones in greenhouses or other covered enclosures. But that’s just me.

Next: Step 5 – Set off your flytrap’s traps with your finger.

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