Winter Carnivore Cleanups – Cape Sundews

Backstory: it’s January, we don’t have any distractions, and the plants need us. Therefore, it’s time to discuss methods to clean up carnivorous plants for spring. For details, go back to the beginning.

For today’s cleaning exercise, we’re going to focus on both the carnivorous plant and the container in which it resides. For the most part, many smaller sundews survive and thrive quite nicely in ornamental glass bottles, so long as the glass is sufficiently clear (tinted glass bottles aren’t recommended) and the plant is able to get enough light to grow without too much heat building up inside. For most beginner sundews, they either don’t mind or actively enjoy temperatures reaching 90 degrees F (32.22 degrees C), but Cape sundews (Drosera capensis) is a decided exception. Hailing from far southern South Africa, Cape sundews prefer things a lot cooler: they generally prefer to stay below 80 degrees F (26.66 degrees C), and in fact tend to go into shock at temperatures where other sundews are just getting going. In North Texas, I actively recommend keeping them under artificial light and in the vicinity of an air conditioner vent during summer: a common ailment in July and August is to see the tips of leaves looking as if they were burned with a cigarette lighter. Cape sundews tend to spread through carnivore collections in greenhouses because of their enthusiastic and prolific seed production, but without climate control, those feral sundews usually burn off during a Dallas summer and only reemerge in fall as temperatures start to drop. Even a day of higher temps can be debilitating or even fatal for Cape sundews, depending upon how high the temperatures went and how long the plant went without a break in the heat.

To get around this, the preferred method of offering Cape sundews at Triffid Ranch is within the confines of an Erlenmeyer flask. These flasks both allow air circulation through heated air escaping through the top and consolidation of humidity in the bottom, and a slight increase in water loss through the open top is worth the effort. In addition, most customers love having a piece of lab glassware in which to display their new sundews. For the most part, Erlenmeyer flasks are great, but cleaning the inside of the container offers a particular challenge because of both the narrowness of the neck and the height of the total flask.

For this exercise, the following tools or their analogues are highly recommended:

Garden mat or old towel
Isopropyl alcohol, bottle or wipes
Spray bottle filled with rainwater or distilled water
Long tweezers or alligator forceps
Tamper

The most important consideration with tools used in tall glass containers is making sure that the tool is long enough to reach the bottom while still retaining a grip on it. This becomes important when cleaning up around the base of a Cape sundew. Like most sundews, Cape sundews constantly produce new leaves, leaving the old and dead ones around the base of the stem, and while their accumulation won’t actually hurt the plant, they’re unsightly. Thankfully, after a short time, the leaf stem rots and the rest of the leaf drops, so it’s simply a matter of having tweezers or another tool that can reach and grip them. Alligator forceps are an excellent choice, but if all else fails, using a straight wood or plastic rod to tease that detritus away from the base of the plant works. In some cases, a combination of techniques might be necessary, especially with well-fed and well-lit sundews that threaten to outgrow their container.

The photo above also highlights a major issue with most glass containers and their botanical contents. Being a natural product, peat can be full of seeds and spores without you having any sign of issues, and some moss and fern spores are tough enough to survive most efforts to sterilize growing media. Even if efforts to sterilize growing media are successful, more spores can blow in on the wind, and once they find the right conditions for growth, they can and will do so. (Because I use a combination of milled Canadian peat moss and a New Zealand-sourced long-fiber sphagnum as a top dressing in most Triffid Ranch enclosures, this means that most of the ferns sprouting in an enclosure are native Canadian or Aotearoan species. Every once in a while, though, I’ll get a Texas-native wood fern that came sneaking in on the breeze.) The real problem is that you don’t know what kind of fern you’re getting until it’s large enough to identify, and many of them will grow out of control in a stable environment such as inside an Erlenmeyer flask. Worse, many species throw down big mats of root fibers along the bottom of any container, meaning that attempting to remove a mature fern will yank up part or all of the container’s other contents in the process. In a container as small as this, not only is it a good idea to remove all sprouting ferns during a cleanup, but keep an eye open for more sprouts through the rest of the year, unless you like uprooting everything every six months or so.

After working with several particularly large and deep containers over the last couple of years (two dead Lava Lamps and a glass water cooler jug), I picked up a secret weapon in the War Against the Wayward Ferns. Some ferns produce root mats almost impossible to ferret out by themselves, but crushing and cutting the base where the leaves meet the roots is a lethal trauma. That’s when a quick search for used surgical tools came across the wonder that is a biopsy punch. Intended for getting samples of tissue from deep within a body, biopsy punches both cut AND hold, and they do it as well with ferns as with humans. With a bit of practice, a biopsy punch can be used like alligator forceps to pluck single leaves or fernlets from a container, but they can also be used to crush and chop up plant parts that can’t be removed easily. Crunch a fern base to near-pesto, and the odds are pretty good that it won’t come back.

Done with plucking, mashing, cutting, and yanking? It’s time to give everything a good misting to wash dirt down the side of the container and settle everything. While a standard trigger spray bottle can get the job done, there’s always the issue of having to tilt both spray bottle and container in such a way that enough water gets to the bottom of the container without constantly having to reprime the sprayer. This can be bypassed either with a spray bottle with a pivoting nozzle, or by getting a spray tank and nozzle. A few pumps to add pressure, and a nearly-dry flask gets completely rehydrated in seconds.

One final extra. While the relatively narrow neck and mouth of an Erlenmeyer flask cut back on water loss, the flasks will eventually lose water from evaporation faster than they would if they had corks. Between water evaporating off the sides due to capillary action and water evaporating from the soil and transpiring from the plant, shorter bottles lose water even faster. This means that the best options for Cape sundews are either regular light waterings every couple of days or a good stout watering every week, and more often if the relative humidity in the house or office is lower than usual. (If central heat or air are running, that’s pretty much guaranteed.) Heavy waterings with longer periods between deluges seems to encourage new sundew growth, leading to lots of plantlets coming off the roots in a shorter time than if the plant were constantly topped up. Obviously, experiment to see what works the best for you, but don’t panic if you add seemingly too much water and it puddles on the top of the soil. Most of that will evaporate within a day or so anyway: now, if the whole plant is under water, you’re going to have to consider draining off some of that, but a little excess water won’t hurt a thing. Just watch for ferns as everything starts to dry out.

To be continued…

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