Nepenthes Care: A Different Approach to Growing Tropical Pitcher Plants

In Houseplants & Tropicals
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Welcome to my post on Nepenthes care. This is more an exploration of topics and justification for my approach, rather than advice on “how YOU should grow Nepenthes.” The sections I’ll cover include the primary topics for care: temperature, potting media, water quality, watering methods, misting, humidity, light, and fertilizer. I’ll contrast common knowledge with my perspective so you have insight into why I’ve chosen a designated approach. Clicking those links will jump you to the section or continue reading for full coverage.

If you’re new to this plant genus, you will want to brush up on what “highland” / “ultra-highland” means—here’s a good post from Red Leaf Exotics on Nepenthes temperature requirements and there’s a nifty tool from Tom’s Carnivores to calculate the temperature requirements of different Nepenthes species which is based on the plant’s elevational range in nature—that calculator does a really fantastic job of blending data from the species natural range and gives you a hint at where the hybrids should optimally grow. Tom also has a good general care guide on Nepenthes care; however TL;DR: The higher elevation a species naturally grows on a mountain, the more specialized its adaptations are for cooler day and night temps. Conversely, lowland species (from near sea level elevation) require high day and night temps.

For context: I have grown Nepenthes on and off for over 16 years, having about 7 years continuous experience. If you are new to my blog, I’m a Canadian plant hobbyist that primarily grows and hybridizes orchids. I write about my experience growing these and other unique plants to offer other growers a more rounded understanding of plant care; you know, beyond advice like, “needs low light and don’t overwater.”

My Nepenthes collection: is comprised of 25 types, which are mostly hybrids of highland or ultra-highland ‘toothy’, cool-growing species. This includes crosses of hamata (10), villosa (3), edwardsiana, diabolica, rajah, robcantleyi, and veitchii (4); all of which I am growing above their recommended temperature ranges. The highlights of my collection include a villosa x hamata and a recently-acquired hamata x edwardsiana. There are photos of my plants at the bottom of this post if you want to see the setup. I have one highland species, N. aristolochioides (an experiment) and a few lowland species including northiana (also an experiment), ampullaria, rafflesiana and albomarinata. I also have a couple dozen Nepenthes ampullaria hybrids that I started from seed.

My Nepenthes setup & conditions: All are in a 130 gallon terrarium, with a humidity that averages about 65–75% during the day and goes up to 90-95% at night. I use 3 different brands of full spectrum LED grow lights that draw a total of 120watts and provide the plants with about 90–100PPFD (or 4–4.5% sunlight). I live in an apartment in Calgary, Canada, but my indoor temps are seasonally much warmer than recommended for highland Nepenthes; day temperatures consistently reach 30°C during June, July and August (never exceeding 33°C), but non-summer daytime temps average 22–26°C. The point about the temps not exceeding 33C is important—because the plants are not in direct sun, this means the leaf temperature also never exceeds 33°C. The coolest it ever gets in winter is about 17.5C on the coldest nights. Regardless of season, my plants don’t get the recommended nightly temperature drops of 8-15°C and only get a difference of about 2–5°C. This is why I’m mostly growing hybrids of highland Nepenthes. What really attracts me to Nepenthes are the toothy species (all of which are highland growers), so I’m experimenting on what works in my conditions.

 

Photos of my Nepenthes collection(2023)

 

Recent Nepenthes Photo Update – January 2024

As a caveat: I am not suggesting what I’ll cover in this article is the right or best way to grow these plants. I am conducting a long-term experiment and sharing my thoughts and findings. My hope is that this works as a lens to contrast your current view of Nepenthes care, especially if you’re similarly interested in highland hybrids and live in a more mild summer climate. While I have been growing Nepenthes for a good period of time, my current plants have been in my care for a little over 2 years at most. In Nepenthes timelines, that is not long. Some particularly slow-growing species can take upwards of 10+ years to mature. I have not killed any Nepenthes in my current collection (which I feel that is a good litmus test of how things are going), but time will tell if my conditions are good or not. If you’re growing Nepenthes species only (and not hybrids), be more cautious—they are often highly specialized in their adaptations to grow and thrive under specific conditions, and they may not tolerate sub-optimal conditions.

Something else you should know…my first group of Nepenthes…I killed them all. I was growing those plants in an indoor greenhouse, which malfunctioned and blew a seam while I was away on vacation. All my plants dried out before I returned and I lost a couple thousand dollars worth of plants. These were rare Nepenthes species imported from Wistuba (including N jacquelineae, rajah, and macrophylla), along with a bunch of orchids. As you can imagine, I was crushed and a little embarrassed, so I took a break from Nepenthes. I start again in 2019, a few years after starting this blog, by chance when Brad (from Brad’s Greenhouse) sent me a couple freebie neps with an order of Pinguiculas.

Hybrid Vigor == ‘Easier Plants’: I mentioned my plants are mostly hybrids. I have opted for these because hybrids tend to be more resilient and easier to grow. They have a blend of genes and traits from their parents, and this often makes them more versatile when it comes to their care requirements. This outcome is typically referred to as “hybrid vigor” or “heterosis”, because hybrid plants often grow faster or are easier to keep than their parent species. It doesn’t mean hybrids are better…they’re just less restrictive about the specificity of their care, and sometimes that means they’re more tolerant of the conditions in our home. Hybrids are typically less-able to withstand the extreme conditions their parents tolerate, so the term “hybrid vigor” can be slightly misleading. I’m getting a bit off track, but I want to be clear that most of my Nepenthes are ultra-/highland hybrids and I’m expecting this will influence my success growing them in slightly warmer conditions.

My promise: If I fail…I will update this post and note which plants don’t make it. I’ve included a list at the very bottom of this post, if you want to know which nepenthes hybrids I have.

 

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Nepenthes Care

Temperature Requirements for Hybrids of Highland Nepenthes

As I mentioned, my temperatures are considerably warmer than those recommended for highland and ultra-highland Nepenthes (especially during summer) and I don’t give my plants the recommended nightly drop of 10-14°C. I’m not bragging about that, I just can’t reasonably get my temps any cooler. I live on the Southwest corner of a brick building (which gets direct sun all day long), with limited air conditioning. On sunny summer days, my place heats up quickly. I do not want to rely on a fragile system to keep my plants alive out of fear of repeating past mistakes. Instead, I’m testing my theories and the limits of my plants. For now, have opted not to build an expensive, loud, and space-taking cooling system (that I expect would eventually fail).

My summer temps go from a daytime maximum average of about 28–30°C to night temps of ~25–27°C (only about a 3°C degree drop). My winter temps are more reasonable with the days being around 21–23°C and 18–20°C  at night (again about a 3 degree drop). As an example of how not good these temps should be, here are the suggested temperature ranges based on Tom’s Carnivores temp calculator:

  • villosa x veitchii, one of the more resilient villosa hybrids that should probably ideally get 14C nights and 24C days. My summer temps are typically warmer -which interestingly is when this plant tends to put on the most growth- and my winter lows are at a minimum 4C warmer and more often around 6-8C warmer – but the plant is doing great:
    Progress Update (Jan, 2024): Before/After, 1.75 years growth
    Nepenthes (villosa ‘BE-3225’ x veitchii ‘Bario/Squat #3734’) BE-4045
  • villosa x robcantleyi, recommended temps: 9–16°C nights & 19–26°C days. My night temps are ~7°C warmer in winter and over 13°C warmer in summer. This cross is one of my “most highland” hybrids (making it the least likely to survive my conditions). Over the past year it’s put on some really good size—though it is a bit fussy about water (like robcantleyi tends to be); here’s a before/after comparison:
    Progress Update (2023): Before/After, 11 months growth
    Nepenthes villosa x robcantleyi
  • rajah x klossii, recommended temps: 10–18°C nights & 20–28°C days. My night temps are consistently about 5–12°C warmer than the suggested average (basically at the upper maximum recommended temps). This is one of my most vigorous Nepenthes, putting out a new leaf every 4-5 weeks—but it does grow faster in the summer. It made about a 3x leaf jump near the end of summer and then again in spring; the plant is also very rooty. Here is a before/after photo comparison taken 10 months apart:
  • ventricosa x attenboroughii, should have 13–18°C (55–64°F) nights and 23–28°C (73–82°F) days, which is pretty reasonable. N. attenboroughii is a highland species and should have cooler nights in the range of 13–17°C. The contribution from ventricosa should make this a pretty easy-going plant, but I’ve included it in this list mainly because it’s an interesting and novel hybrid with a lot of potential:
  • villosa x hamata, easily the most extreme (and most expensive) cool-growing hybrid in my collection; this cross theoretically should require an average of 12°C nights and 22°C days. The two parent species from this cross also have the lowest temperature tolerance compared to all my hybrids, with villosa tolerating lows down to 6°C nights and hamata to 10°C nights. So, I’ll admit that I was very nervous about this particular hybrid on the chance that it was intolerant to ‘warmer’ temps. However, so for, things seem alright; it’s been 5 months and it’s producing a progressive increase in growth with pitchers or leaves getting a little bigger each time. I expect new plants to take a bit of time to “settle in” before they really make big jumps, but this one is finally in the process of producing a larger leaf. Interestingly, another Canadian grower, Binni L., has a sibling of this cross (from the same BE group) and he is giving his plant about 2x the amount of light (220PAR compared to my ~100PAR)—his plant is starting to make significant leaf jumps, so I suspect mine won’t be too far behind.
    Here is a photo of my Nepenthes villosa ‘BE-3225’ x hamata ‘Tambusisi’ (BE-4099) when it arrived in early October 2022 compared to March 2023:
  • hamata x edwardsiana, my pride and joy (and second most expensive nepenthes) should have night temps of ~13°C and 23°C day. I got this plant October 2022, so it’s new (in my care under 6 months); it’s been establishing but hasn’t produced pitchers yet. Time will tell how it fares.
    Before/After 5 Months
    Nepenthes hamata x edwardsiana, Wistuba Clone

  • aristolochioides x diabolica, the other ‘most highland’ plant I have, which should have 10–14°C nights and 20–24°C days. This makes it similar to villosa x robcantleyi and villosa x hamata for it’s temp requirement. My night temps are about 7–14°C warmer than recommended. Unlike my other plants, this was a mature cutting when I got it, not a seedling. They say older plants cannot tolerate warm temps, so I thought for sure this would be doomed. Initially, it looked like it might be struggling. It grew 4 leaves in 4 months (fast), but none pitchered. By the end of summer, the oldest new leaf finally produce a pitcher—which I thought was oddly delayed, but then I found out from Brad (of Brad’s Greenhouse) that vining plants often don’t produce pitchers if they don’t have a secure anchor for the tendrils. Since then, it developed a basal growth (which pitchers consistently), has filled the pot with roots, and the upper vine continues to grow while not producing pitchers.

     

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Is temperature *really* that important for Nepenthes?

Maybe…but temperature is complicated: I’m conflicted about how important ‘temperature specificity’ is for Nepenthes, or at least for all highland Nepenthes; I’ll explain in detail my thoughts relating to this. First, I often wonder if growers have oversimplified the topic based on a knee-jerk reaction to Nepenthes that struggle to settle in OR hit a wall after a few years of care. The prevailing belief is that temperature precision is required because it influences the plant’s metabolism—what exactly that means, no one in the plant community seems to be able to articulate. My understanding is that there are two angles to plant metabolism – 1: in the cell’s mitochondria and 2: in relationship to the products of photosynthesis within chlorophyll, where the reaction can become phytotoxic (when a plant is given too much light) or conversely when they produce insufficient energy in a deficit of light. How temperature specifically affects either of these components, I haven’t been able to get to the bottom of (and I suspect every other grower has reached this same limit in knowledge because the information available relating to this might not be that accessible or easy to understand). Some feel temperature is so important that if you grow a Nepenthes even slightly outside its designated range, it will inevitably kill the plant—and maybe some species are really that specific with their needs, I’m not saying it’s not true…but when it comes to hybrids I have doubts.

I have my suspicions for a couple reasons. The main one being the lack of detailed knowledge on the topic beyond anecdotal perspectives (and if that’s all we have to go by…that’s better than nothing), but it means it’s open for analysis and experimentation. I know temperature affects variables beyond the production of stress metabolites in a plant, and I don’t think many growers have significantly or methodically explored those other variables. For example, temperature affects the transpiration rates through a plant’s leaves, which affects water draw through the roots, which impacts the environment around the roots. Excessive (and constantly) high humidity in combination with high temps can limit a plant’s ability to transpire. Direct sun on a leaf can easily drive surfact temps above 40C, while plants grown under LEDs at room temperature don’t get this same temperature spike (and therefore may not suffer the same heat-related stressors). Additionally, the temperature of water affects the solubility of certain minerals (and oxygen) which can impact elements of nutrient availability and conditions favorable for microbes and pathogens in the root area. To be explicitly clear, alkaline minerals like calcium and magnesium are more soluble at lower temperatures—but if you’re not offering those elements it doesn’t matter how low your temperature is, you won’t end up with more dissolved in water. For all these reasons, I feel there are variables that operate adjacent to temperature that may also affect plant health—many of which have not been thoroughly explored or documented. I’ve been adjusting those other parameters (instead of focusing exclusively on temperature) to see if I can still achieve success with the plants I have and so far my results seem very promising. I’ll cover those changes more in the potting soil and water quality section below, but I’m not done with the temperature topic quite yet…

I mentioned that the common belief is that temperature affects the metabolic rate of Nepenthes plants. Too hot or too cold (depending on the species) and it leads to a buildup of volatile compounds in the tissue called metabolites. I never did find any explanation on how cool or warm nights aid in reducing these metabolites, but the bottom line is that temperature stress leads to death. This study on temperature adaptation of four Nepenthes species evaluates 3 lowland and 1 intermediate species: N. ampullaria, N. northiana, N. rafflesiana and N. minima; it has largely been extrapolated and applied to all highland Nepenthes species, to justify the perspective that temperature impacts Nepenthes metabolism. However, to me there at least a few faults in this extrapolation: 1) the occurrence of metabolite markers are inconsistent across the lowlanders (as an example, you might expect rafflesiana and northiana would have similar metabolite footprints when grown outside of their preferred temperature, but they don’t); 2) none of the species used in the study are exclusively highland or even ultra-highland; 3) a sample size of 4 species, really does not accurately represent the 180+ species within the genus; and lastly, ampullaria (one of the most adaptable species, able to grow at a very broad range of conditions) doesn’t appear to exhibit any pattern of metabolites compared to the plants grown within their optimal temperature range. So to me it feels like conclusions have been made with limited data to support the original theory—but truly, I am not a scientist and may not have interpreted the data accurately, I encourage you to look at the study for yourself and draw your own conclusions. I was looking for patterns to see consistencies and didn’t find what I expected.

It’s also incredibly difficult to find exactly what the signs and symptoms of “heat-stress” are in highland Nepenthes. When plants are LIGHT stressed, the symptoms are clear and show up quickly: too much blue light and you get yellow chlorosis from phytotoxicity that happens during photosynthesis; too much red spectrum and the plants blush red or purple with anthocyanins to reflect the excess light not needed by the cell. Indicators of heat stress seem…undefined. I have heard general accounts from different growers, that highland plants decline quickly (in as little as 3 months), getting root rot, producing smaller leaves, smaller traps, followed by leaf distortion and eventually a fast collapse—to my delight, they did cover this topic in the Highland Nepenthes Round Table video by the International Carnivorous Plant Society (however, by the assessment there, my highland plants are not suffering because roots are growing and leaves are increasing in size); their perspectives generally aligned to the above expected decline within the first 3-6 months.

Others say, “smaller plants are less impacted by temp” and feel that it can take up to 3 years before heat stress inevitably kills a plant. When we get into timelines of over 1 year, I question the accuracy of an assumption like that. In 3 years a lot of things can go awry, like potting media degradation, malnutrition, pests, and so on.

On one blog, the Nepenthes Diary, the author reports growing a N. jacquelineae at sub-optimal temperatures; they note that the plant started out strong, grew vigorously, and put on size with many leaves for 3 years…but then ended up dying from a mite infestation. They believed the susceptibility to the mites was a product of the plant’s stress related to temperature (and maybe it was?). But upon reading that, I see red flags other than temperature. For example, a species like jacuelineae may not have been exposed to this particular type of mite in it’s native habitat (and may not have any sort of resistance), second…mites are a pest and they suck! I’ve had a type of “false mites” or the “red flat mite” decimate my phalaenopsis collection, those mites later jumped to my Monstera Esquelleto and continued to do severe damage on that plant. When mites find a plant they like, they are vicious, but they can also skip plants in the same group while destroying others around it—it doesn’t mean the host plant was suffering from temperature stress. In these cases, the only way to stop the destruction is to kill the mites.

Without insight into the exact science of temperature stress, including the speed of decline, and the specific signs and symptoms to look for when a plant is temperature stressed, I have to wonder if the issues are always related to sub-optimal temperature and metabolic speed, or maybe the death of these plants is related to something adjacent within their general care…like a mite attack or old, degraded, compacted sphagnum moss (which we’ll cover more below).

Let me give you some additional insight to my thoughts on temperature. Paphiopedilum orchids (also native to SE Asia, including Borneo), commonly get root and leaf rot when grown too acidic or when given too little calcium—rot is an outcome that can happen as quickly as a few months or take many years before the right trigger (presence of a pathogen) leads to an infection and death of the plant. Like Nepenthes, many Paphiopedilum species similarly are lowland or highland growers. One species, Paphiopedilum rothschildianum (500–1800m) even shares some overlapping elevational range as Nepenthes rajah (1500–2650m) on MtKinabalu, Borneo. Without enough evidence, a grower could assume P. rothschidianum is hard to grow because of its intermediate-to-highland temperature requirements and that growing them out of their optimal temperature range inevitably leads to stress and then rot. However, Paphipedilum rothschildianum are often grown in warm-to-hot greenhouse conditions by growers in Florida, Hawaii, and California, and indoors by growers like myself. It’s a challenging species to grow because it is intolerant of overly acidic root conditions (because its natural habitat is composed of rocky substrates that are alkaline, never acidic). This is common with many terrestrial Paphiopedilum and slipper orchid species. With Nepenthes culture, I don’t see a significant exploration of other variables (like pH and nutrient compositions in the root zone—because people assume they’re fully carnivorous), so it has me scratching my head a bit.

Questions arise like: If highland Nepenthes cultural issues were exclusively related to the metabolic rate, then couldn’t a person adjust the other parameters that lead to a buildup of those toxins? Like shortening the photoperiod and light intensity to reduce the buildup of said toxins produced during photosynthesis? Further, how exactly do low night temperatures reduce the presence of volatile compounds in highlanders, but increase them in lowland species? Based on the above study, the gist is that different compounds build up in different plants based on temperature…but then, what happens if you hybridize a lowlander with a highlander? What metabolites are produced when those hybrids are grown hot or cold? What happens if you hybridize two highland species that produce different metabolite markers but are both highland species? Better yet, what happens if you make a highland x highland cross and grow the seeds in lowland conditions, allowing for “natural selection” of the progeny? In a lot of cases, it has been proven that highland hybrids are able to grow in much warmer conditions than their parent species (look to hybrids of N. lowii for example, which are significantly easier to grow than the species itself). I want to understand exactly why and how this all works, and with so many unanswered questions or “fuzzy facts”, it’s hard for me to blindly buy in to these ideas—especially given that my plants are doing quite well…

I do want to be explicitly clear: I’m not saying temperature isn’t important…I just don’t know if a few degrees difference is really that impacting.

Why else do I question the impact of temperature on plants? I have many “highland” orchids that come from equally cool or colder habitats than any Nepenthes I grow. Those orchids have done well for me for over 4 years now—namely, Phragmipedium kovachii (1,600–1,950m), Paphiopedilum tigrinum from Yunnan, China (1,200–2,200m), and Corybas pictus (700–2,000m)—along with other orchid species, many which are from latitudes much further North than the Borneo and Sabah area (up into Myanmar [Burma] and the mountains of the Yunnan province of China). Those plants would subsequently experience seasonal nightly temperatures as low as 2C. Yet, all of those species do well for me in my current indoor conditions (provided I keep their max temperature under 35C and keep their water slightly alkaline as most are from limestone habitats). I should note, paphs from alkaline substrates specifically do poorly in pure moss AND the most damage I’ve ever done to those plants, happened when I was tinkering with pH…not temperature. So…if orchid species are flexible with their temperature but inflexible with pH or nutrient environments, why wouldn’t the same apply to Nepenthes plants?

Let’s move on to the rest of Nepenthes care…

Potting Media for Nepenthes: Inert with a chance of organic
(Akadama, Kanuma, Pumice & Rock Wool)

For the majority of my Nepenthes I’m using a mostly rock-based or inert media that maintains structure and doesn’t decay. I also use an additional thin top-layer for moisture retention which is composed of either grow cubes or sphagnum moss. In the “below moisture barrier” potting mix, I use about equal parts pumice, larger perlite, and turface (baked red-clay fragments, which can be substituted with LECA, Adadama or Kanuma), and I add a very small amount of organic media (10% ratio of bark and a bit of peat or fragmented sphagnum moss). This is essentially a modified semihydroponic growing mix, but I typically do not keep the roots continuously wet (though it does happen from time to time). I try to let the water tray dry out between waterings while watering regularly enough to prevent any sort of plant dehydration.

Semihydro has its faults, but based on observation of the Nepenthes-growing community, it seems many growers successfully use the smaller rock-based media comprised of akadama (bonsai version of clay/LECA/turface), kanuma (bonsai version of volcanic rock), pumice, perlite and so on. It makes sense to me why these options work—it comes down to media longevity, structure, airflow, and reducing root disturbance when it’s time to repot.

My Nepenthes potting mix with mostly inert media

Side view of pot showing layered approach to potting mix w/ top layer of moisture-retention

Example showing top-dressing of rockwool for moisture

 

I mentioned challenges with semihydro – the main things to watch for when using an inorganic media are:

  • A dry top layer which can make it hard for new roots to survive if they’re emerging from the base of the plant. I resolve this with that top-layer “moisture barrier” of grow cubes or sphagnum moss I already mentioned above. This raises the moisture barrier in the pot so the new roots aren’t hitting any dry pockets and aborting. I still do my best to maintain high general humidity (more details below).
  • Dry pockets or lack of even hydration across the entire root zone, which can cause root death if your media isn’t evenly moist. I avoid this by doing active weekly waterings (where I run water through the pot until it comes out the bottom), AND by doing a full pot soak every 2-3 months. When doing this, I’ll sit the whole pot in a bucket (or bowl/cup) of distilled water to saturate the entire root ball right up to the base of the plant. That is followed by draining which flushes away any buildup of “yuck” that may have accumulated in the substrate. With species from limestone or ultramafic rocks, I’ll even do this with tap water to bump the pH up and bring in alkaline minerals like Calcium & Magnesium.

Plant Hydration: Water Quality, Watering Methods, Misting & Humidity

Humidity, active watering, and water purity are all related to plant hydration, so I’m going to cover these topics individually for precision. The overarching concept is to always have well-hydrated and not water-stressed plants. Wilting leaves…are a sign of stress and I strongly recommend avoiding letting any plant reach its wilting point. If a plant is so dry that it’s started to wilt, it could cause damaged (either at the leaves or roots) and that could set the plant back months or even years.

Water quality for Nepenthes

Not so pure as one might think: I use distilled water but add a touch of alkalinity once a month by adding 20% tap water. My tap water has a pH of 7.9 and TDS of 250ppm calcium carbonate, so that water is about 50ppms CaCO3 and has a pH just over 7. The calcium from this remains in the potting media, preventing extreme acidity. This does affect the sphagnum moss, which sometimes looks a little sickly (brown tips), because sphagnum really doesn’t tolerate minerals…but my goal is to avoid root rot on my glorious nepenthes, not to grow lush sphagnum moss.

Why water quality isn’t a simple topic: Common perspectives on water for carnivorous plants is that the water MUST be extremely pure and…for bog plants (like Venus Fly Traps and Sundews), I absolutely agree! Peat bogs are extremely acidic, have low TDS/PPM readings, and lack minerals like calcium—that’s what makes peat bogs incredibly inhospitable to most common species of plant. However, given the ecological range where many Nepenthes grow, I believe there is more to their needs than ultra-pure water. Pure water has some unique chemical properties; it’s unbuffered, easily acidified and that can impact plant root conditions and health for species not adapted to incredibly harsh conditions like this.

Nepenthes from alkaline soils: A handful of the highland and ultra-highland Nepenthes species grow exclusively in ultramafic, serpentine soils; notably including Nepenthes burbidgeae, N. edwardsiana, N. rajah and N. villosa. Conditions in those ecosystems have likely influenced the plant’s adaptations to survive and thrive within that really specific niche, but conversely those adaptations could limit their ability to thrive in other conditions. Do you notice those species are also the ones people find “finicky” and prone to root rot? It’s interesting because ultramafic soils are slightly basic (or specifically not acidic). A few other Nepenthes species also grow in alkaline limestone regions in similarly high pH soils; notably including: Nepenthes treubiana, N. biak, N. ventricosa, N. campanulata, N. northiana, and N. mapuluensis. Others like Nepenthes ampullaria, N. gracilis, N. lowii, N. mirabilis, N. stenophylla, N. tentactulata, N. veitchii, N. epiphytica, albomarginata and N. vogelii can be found growing in limestone areas but are not exclusively restricted to alkaline soils. You may notice with this latter group how many of them are considered “easy species”—that resilience likely comes from their adaptability to survive in a range of root conditions, both acidic and alkaline, while other “hard species” like northiana, campanulata and rajah, are obligately associated with alkaline soils.

What about hybrid vigor? It did occur to me that hybrids are also likely to be more tolerant of a range of soil conditions, which is why I purchased a Nepenthes northiana species to test my theories with. N. northiana is known to be quite challenging, and my hunch is that it’s related to soil chemistry and root zone pH; this has been discussed before by other growers. The plant I bought arrived with no roots and looked a little shabby with cracked leaves that were decreasing in size, so it will be interesting to see the impact of soil alkalinity on this ‘alkaline-loving’ Nepenthes species. Initially, it was very slow to establish and it started losing many leaves, and produced smaller leaves with no pitchers; in desperation, I completely soaked/flushed the potting media with tap water (7.9pH, 250ppm CaCO3), and from that moment forward, the plant has turned around—new leaves are progressively getting larger and it’s started producing pitchers. This change happened during coolest part of the winter when my indoor temps were more aligned to intermediate conditions (not highland, like N. northiana is supposed to prefer), so what I initially thought was a decline of temperature was clearly remedied during the coolest time of year. I’m excited to see how it will do in the summer when temps are higher and closer to lowland conditions.

Why soil pH matters? Plants highly adapted to alkaline soils are typically (and not surprisingly) not well-adapted to withstand extremely acidic conditions. Either they lack the resistance to the pathogens that may thrive in highly acidic conditions or they are more reliant on minerals (like calcium and magnesium) being abundantly available in those conditions to fulfill proper cellular function. Further, some adaptations to survive in alkaline conditions, could result in plants experiencing nutrient toxicity when grown in an acidic environment. Some species of plant (not Nepenthes that I know of) will produce citric acid at the root zone to better survive in alkaline environments and free nutrients, but in an unbuffered or already acidic environment, that acid can create inhospitable conditions. All of my approach to this comes from my understanding of the impact of soil pH and plant ecology, based on my analysis of water, geology and soil composition for orchid care over the last decade. I cannot think of a reason why this context cannot be extrapolated to Nepenthes plants (which come from the same habitats as many orchids). However, it’s extremely rare to find specific information on these topics (where biology overlaps chemistry and geology with horticulture in mind, while accounting for a really specific genera of plants like Nepenthes). So all of this is still just an educated guess—a hypothesis—not something that is easily cause-and-effect bound (which is why I’m experimenting).

Bringing water quality back to potting media, in a full-circle ideation: Most good Nepenthes growers opt for a potting mix blend of sphagnum moss and perlite. It’s a tried, tested and reliable option…mostly. I have read multiple reports of people’s plants suddenly getting root rot, which is especially common with select species like Nepenthes rajah and/or Nepenthes northiana.

One grower reports, “Rajah will root rot very quickly, and hates to be repotted. Trust me on this I have gone through 3.”

This perceived fragility is a red flag to me. From my experience using sphagnum for many other plants, I also know sphagnum has a diminutive timeline of use. As it ages, it goes through stages: compaction, decay, acidification, and that’s why growers need to repot plants grown in sphag moss so regularly—to keep the roots healthy, oxygenated and “not sour.” Failing to repot on time often results in root rot.

A potential problem with Sphagnum: it’s acidic and as it decays it becomes MORE acidic. In ultra-pure, unbuffered water (like distilled or rainwater) the pH is “unchallenged” and easily drops. In fact, just the interaction with pure water and atmospheric carbon dioxide drops the pH of water to about 5.5pH (which is why bottled water often has a pH as low as 4 and rainwater has a pH of 5.5-6.0, not 7). Sphagnum moss naturally has a pH around 3.5-4.5pH, but can go even lower as it starts to decay (down below 3.2pH); the impact of extreme acidity like this, is that the “soil” pH can result in that of vinegar or wine—creating bog-like conditions. Very few plant species are adapted to conditions like this, and this is strongly the case with plants from alkaline habitats.

Low pH impacts how nutrients become available to the plant and which microbes flourish and thrive. Like plants, individual species of microbes (fungi & bacteria) have a limited range of pH that they can thrive in. Plants adapted to neutral or alkaline (not-acidic) conditions may not have the disease resistance to withstand “new” pathogens that are not normally present in their higher-pH environments. Ultramafic serpentine soils (where some Nepenthes grow), are high in copper, nickel and other toxic metals. Fungicides and some insecticides often use copper or Sulphur as the active ingredient—which could give Nepenthes from those areas disease resistance when grown on the right soils (but what happens when these plants are not grown there?).

As moss compacts and decays, airflow is also reduced choking roots and shifting the balance of microbes. Then we see symptoms like “root rot” become more common in plants like Nepenthes rajah, as a result of bad root conditions. Maybe…(but maybe not). Clearly, most people have a great deal of success with sphagnum, so I’m not saying this is a guarantee—it’s all about that timeline of degradation and the individual species’ adaptation to its environment. My plants are mostly highlanders from ultramafic soils, and that’s why I’ve opted for a non-sphagnum-heavy mix AND why I use slightly alkaline water once a month.

Another thing I don’t like about sphagnum is repotting. Roots grow into the moss and get entangled. With Nepenthes often being such slow-growing and fragile plants, I don’t want to risk setting them back by damaging roots when I must pick out the old decaying sphagnum. I want the repotting effort to be as minimally invasive as possible, while also allowing a plant to build a robust root system. Some of the best-grown plants I’ve seen in rock-based media were literally packed with roots…how do you deal with that if the roots are deeply entangled in moss that eventually decays? For rock-based media, you just move the whole plant and old media into a new pot, fill in around the root ball, and disturbance is minimal.

Watering process – misting Nepenthes

Normally, I liberally mist my plants at least once a week. Some people say you shouldn’t ever get leaves wet because it causes fungal or bacterial infections—which it definitely can if the leaves stay wet for too long. However, I think water is supremely important for effective plant growth, so I like to drench my plants and then encourage a quick-dry. After a good watering I’ll even blow the leaves and crown out to remove water and then I’ll increase airflow in the terrarium for the next few hours. If the humidity is too high and the leaves are wet, some will start to get spotting (leaf mold in some cases or edema in others) and you can see that in some of the photos. Airflow and ebb/flow cycles of rain followed by dryness is important with almost every plant species, so I make sure the humidity isn’t over 85% for days in a row and let the humidity go as low as 60% directly after heavy watering.

The anatomy of Nepenthes leaves actively funnels water toward the stem and down to the root ball. They’re physically adapted to direct water to the roots, so I soak the leaves to the point of water runoff. Then I’ll blow off any large beads and increase airflow in the terrarium for the next 3-5 hours, until no water is visible on the leaves. The fungal and/or bacterial issues can also be related to a plant’s overall health, which also relates to nutrients and again pH.

Photo of Wet Nepenthes Leaves After Being Misted – though I would recommend blowing the water beads off to reduce chance of spotting
Airflow is increased following a misting to expedite evaporation. Leaves should not be wet like this for longer than a couple hours.

 

Watering process – Flood/Flush Irrigation

I mentioned I soak my plants every few months. When I do that, I’ll soak the whole pot in water right up to the base of the plant. Plants in nature get regular heavy rains and monsoon seasons where it pours for days or weeks at a time—a light misting doesn’t always ensure adequate hydration of the full root mass. Plus, soak/flush watering like this, pull toxins out of the root zone as things decay, or as the plant exudes chemical compounds. It’s a practice that has worked very well for my orchids, and I wanted to keep the care for my nepenthes as close to the care I follow for my orchids. Not only do they come from the same habitats, but my orchids do very well for me.

Humidity

In 2020, I experimented growing a couple Nepenthes at room humidity (as low as 25%) in an actual hydroponic setup (with water always in the bottom tray); those were my burbidgeae x campanulata and rafflesiana plants. While they didn’t die, after a full year of this treatment they didn’t really look like they were thriving either. The burb-camp hybrid rarely pitchered and the raff pitchered but had a lot of leaf spotting (though this leaf spotting didn’t totally resolve with higher humidity). I ended up putting them into the terrarium and focused on providing better humidity. Both pitcher more consistently now even though the light they get in the terrarium is lower than before.

Photo of Nepenthes burbidgeae x campanulata before/after a couple years
Comparing “room humidity” to terrarium conditions

 

If the humidity is too high (85-90%) I make sure to lower it by leaving a bigger gap in the terrarium doors. After a recent misting or watering I leave about a thumb width (1/2–3/4″) gap if the leaves are wet, and then a 1/8–1/4” gap when the leaves aren’t wet. I have no fans in the terrarium, but the room (where I also grow orchids and aroids) does have a big fan constantly moving air. I’m sure this helps initiate some movement into the openings of the terrarium.

 

Nepenthes Light

My suggestion: offer your Nepenthes anywhere from 3—15% sun and it’s often better if you can target the upper limit for highland species. If you want a large pitcher to leaf ratio, try to push your light to 20-25% sun equivalent, but beware that some lower light species may not tolerate this. If you see a significant amount of color change (chlorosis, yellow or red-purple discoloration) it can be a sign of stress in reaction to excessive light levels. Consider dropping the intensity a bit or at least compensate by fertilizing/feeding regularly. A bit of coloration is okay (often desired), a lot (especially yellow) could indicate photosynthetic toxicity or nutrient deficiency.

What others recommend: If you don’t have a light meter, the topic of light evaluation can be a challenging topic. It’s abstract and when someone says “bright light”, your interpretation of that may be very different from what was intended. When I asked people online what light intensity they grew their Nepenthes at, the general gist was “very bright” and up to about 400–500 PAR/ppfd. In other words, “18–22% filtered direct sun”—that is shockingly bright. No other indoor plants I grow get that much light, so it seems a little too strong to me. Carnivero has some good resources on light including recommended range (40–450ppfd), and a comparison of photomorphogenic changes based on light intensity—really interesting stuff. Nepenthes Diary reports best growth between 100–200PAR, and I think that’s a good happy medium target for fast growth and good size pitchers.

Light in my setup: is brighter than “ambient room light” but it’s certainly not 18% sun either. I have 3 LED grow lights above a 3-foot tall terrarium—there’s over 2 feet of distance from the canopy of the plants and the lights. That’s a total of 120W being used for grow lights. At the lowest level (where most of the smaller plants are), the light measures 90 PPFD/PAR or about 4.0% sunlight. As my plants start to vine and close the distance to the lights, the intensity will get stronger which should be good for encouraging flower production (though that may shade lower plants and I’ll have to adjust my setup).

How long to have lights on for: People often recommend 12-14 hours for a photoperiod…mine is 10-12h. At no point in a forest on the equator are you going to get 14h of sunlight. In fact, depending on the side of the mountain and the surrounding plant growth…you might not even get 8 hours of light. If I’m feeling like I want to see more of them, I over-ride the timer as I like. Clearly they’re growing alright and while the pitcher-to-leaf ratio may be smaller than it could be…they’re plants and the leaf surface area is used for photosynthesis. My plants still have some signs of leaf color blushing (which tells me the spectrum and intensity are sufficient). More importantly, my plants don’t look etiolated (stretched), and they certainly don’t look bleached, chlorotic or overly light stressed (read more about plant response to light). That said…I definitely know light is extremely important, and most people underestimate how much light most plants need because we visually perceive light as “bright” vs. “dark”, not measure it like “5% sunlight” vs. “40% sunlight.” My advice to you…spend the time to learn about light. Really get into the topic and become an expert…it will vastly improve your understanding of plants and your ability to care for them.

Fertilizing Nepenthes

A tricky topic too because it’s easy to over do. Some people believe fertilizing can stop pitcher production. I haven’t found that to be true so far, but I have had plants skip a pitcher here and there. From what I’ve seen, halted pitcher production is more related to light and plant hydration (low humidity) than it is to nutrient flow…but maybe I’m just not fertilizing enough to see extensive negative affects.

Root & foliar fertilizing:

I often wonder if Nepenthes are carnivorous because their soils or devoid of nutrients, or if the surplus nutrients they get from insects gave them a competitive advantage—an additional ability to produce more growth, outcompete plants and produce more flowers/seeds for reproduction. Often you’ll see photos of in situ plants like Nepenthes veitchii and Nepenthes macrophylla with enormous leaves nestled among tall trees or lush vegetation. If non-carnivorous trees and shrubs grow along side Nepenthes, how “nutrient poor” can these soils really be?

For that reason, I actively fertilize the soil, leaves and traps of my plants. I use MSU orchid fertilizer at very dilute amount (1/4 tsp per gallon) once a month sprayed on the leaves, and once a quarter I’ll use organic fertilizer in the potting media—this is comprised of guano, insect frass, bloodmeal, rock dust, feather meal, and so on. Like I mentioned earlier, I flush my potting media, so using organic ferts is less “dangerous”; however, it’s still easy to overdo…so always err on the side of caution when actively fertilizing like this.

On the topic of Nutrients: the best grown Nepenthes I’ve seen online seem to be actively root fed in low but regular amounts. Fish emulsion seems to be a popular option that results in hoggy (very big) plants. There’s an interesting discussion at CPUKforum where a grower with an enormous Nepenthes reports, “my Neps that are growing outdoors benefit from fertilization […] I use an organic fish extract […] The fertilizer is applied to the growing medium at half strength every two weeks, or that’s the plan at least, and sometimes it’s poured into the pitchers. Here’s one of the fertilized plants.

Some people resort to “kelp fertilizer” which is often just potassium with plant growth hormones (auxins, gibberellins, and cytokinins), so it’s really not “a fertilizer” (or at least not a full-range fertilizer) and is more like…you eating vitamins and taking testosterone to bulk up. Dosing with plant hormones might be part of an equation, but your plants still need more, like the basic NPK building blocks, to produce mass.

Feeding Nepenthes Pitchers

I feed new pitchers with what I have available… snails, bat guano, insect frass and mealworms. Some of my orchid pots have a pest snail problem. So, I take the mini bush snails, put them in a glass until they dry out. Then, I add a splash of hydrogen peroxide to kill the snail (which isn’t toxic to the plants later because hydrogen peroxide reduces to oxygen and water). What’s left of the dead snail…I feed to the nepenthes. Each pitcher gets 1-2 snails. I’ll put them inside the mouth with long tweezers and crush the snail so the bits fall into the liquid.

Nepenthes food: snails & bat guano

 

I’ve started feeding mealworms base on a video on nepenthes leaf jumps made by cageC64. You can get mealworms at pet stores; they generally stock them for their reptile-owning clientele. For now, new pitchers get a single meal worm of appropriate size. Before the mealworms, I was adding a small scoop of insect frass (blended soldier fly larva) to newly-opened pitchers. After about 3-5 days, I’d add about 1/16 of a tsp; it was messy and I’d occasionally spill on the soil or pitcher, which is why I switched to the mealworms.

Midway through the pitcher life, I’ll also add a single small nugget of bat guano, which comes from my organic fertilizer—it is also sold as “mineralized phosphate”. In one case, I either fed too early or the nugget was too large and this led to nutrient toxicity. The leaf had interveinal chlorosis (yellowing), but I didn’t change anything (or remove the nugget). While the next leaf was stunted, the following leaves after that were significantly bigger (about a 2-3x jump in size). I have continued this practice, but I’m more careful with the size of the poop nugget I feed and waiting for the pitcher to harden off.

Before/After comparison:
Nutrient toxicity discoloration in Nepenthes leaf (left) with leaf jump after a few months (right)

 

Wrap-up: That covers the core perspectives I am following with my Nepenthes care. Again, this post is not intended to persuade you to apply these conditions to your plants, but maybe it gives you some contrasting perspectives. If you want to discuss, message me on Instagram—I’d love to hear your thoughts, especially if you’re a long-time Nepenthes grower. If you want to see photos of my setup or the list of Nepenthes I have, keep scrolling; and if you’re looking for more resources on Nepenthes care, Tom’s Carnivores also has a really comprehensive care guide from a more intermediate-grower perspective—check out his guide on Nepenthes Pitcher Plant Care

 

Photos of my Nepenthes

Before/after progress comparison

 

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List of Nepenthes Types I Grow

Hybrids:

  1. N. maxima x xTrusmadiensis (lowii x macrophylla) BE-3709
  2. N. veitchii ‘Mt. Legaspi Lowland’ x (burbidgeae x edwardsiana/villosa) ‘Malesiana Tropicals’ BE-4053 (2 different clones)
  3. N. veitchii x edwardsiana ‘AW Clone 3’  (New: Aug 2023)
  4. N. villosa ‘BE-3225’ x robcantleyi ‘King of Spades’ BE-4079
  5. N. villosa ‘BE-3225’ x veitchii ‘Bario/Squat Stripe Intermediate #3734’ BE-4045
  6. N. villosa ‘BE-3225’ x hamata ‘Tambusisi’ BE-4099  (New: Oct 2022)
  7. N. hamata x edwardsiana ‘AW Clone17’  (New: Oct 2022)
  8. N. hamata ‘Tambusisi’ x veitchii ‘Bario/Squat-Stripe’ BE-3943  (New: Sept 2022)
  9. N. hamata x klossii BE-4562  (New: Aug 2023)
  10. N. robcantleyi (no clone name ‘1 of 6’) x hamata ‘Tambusisi’ BE-3958
  11. N. ampullaria ‘Brunei Red’ x hamata ‘Tambusisi’ BE-3726
  12. N. burkei x hamata ‘Tambusisi’ BE-3747
  13. N. sibuyanensis ‘BE-3164’ x hamata ‘Lumut’ BE-3562
  14. N. glabrata x hamata ‘Lumut’
  15. N. aristolochioides x diabolica (red hairy hamata ‘BE-3382’) BE-3898
  16. N. ventricosa ‘BE-Clone#47 (CID#0784)’ x attenboroughii ‘BE-CID#2167’ BE-4522  (New: Oct 2022)
  17. N. rajah ‘CID0919’ (1 of 4 Kew Clones) x klossii ‘CID0981’ BE-4071
  18. N. ampullaria ‘Brunei Red’ x campanulata ‘Collection ID-2193 / BE-3044’ BE-3840
  19. N. burbidgeae x campanulata BE-3564
  20. N. ramispina ‘BE-3155 Exceptionally Dark Form’ x reinwardtiana ‘Tambunan Road form’ BE-3663
  21. N. xSt.Gaya [khasiana x (ventricosa x maxima)]
  22. [Seeds Sown] N. [Viking (mirabilis var. globosa) × Hookeriana (ampullaria x rafflesiana)] x ampullaria (Green × Black Miracle)
  23. [Seeds Sown] N. ([((lowii x veitchii) x boschiana) x (boschiana x (truncata x campanulata))] x veitchii ‘Bario’) (from Larry @5Hearts)
  24. [Seeds Sown] N. (((Rokko ‘Exotica’ x boschiana) x veitchii ‘Hose Mountain EP’) x NOID [possibly ((lowii x veitchii) x boschiana) ‘Yellow’])
  25. [Seeds Sown] N. LVB x mollis (from Brian in SoCal)

Species:

  1. [HL species] N. aristolochioides BE-3023  (New: Oct 2022)
  2. [HL species] N. jamban BE-3875  (New: Apr 2023)
  3. [LL species] N. albomarginata ‘BE-3004 – Brunei Green Form’ 1 of 24 clones  (New: Oct 2022)
  4. [LL species] N. northiana BE-3357  (New: Sept 2022)
  5. [LL species] N. ampullaria ‘Williams Red’ x ‘Harlequin‘ BE-3681
  6. [LL species] N. rafflesiana (poss. “Brunei” BE- 4519 or BE-3722)