Basic Cultivation of Highland Nepenthes
by Dave Schloat
Nepenthes (old world pitcher plants, sometimes called monkey cups) hail from Southeast Asia, with some found as far as Madagascar. They grow almost anywhere there is sufficient moisture, from steamy lowland swamps to right below the frost lines of mountains. We are going to focus on the care of those Nepenthes which grow at higher altitudes, but much of this info will be true for the whole genus.
The first thing to realize when cultivating Nepenthes is that there is variability in difficulty and cultivation requirements. You have to know a little bit where a given species is found in the wild to understand their specific needs. I am going to be as general as I can in this article so that you can apply these ideas to the largest range of species, including the picky ones, so don’t be intimidated.
Most species of highland nepenthes appreciate high levels of diffuse light. Some can take full sun if they are adapted to it slowly, however it is best to avoid blazing sun (there are exceptions to this rule, but even those exceptions will grow just fine with the diffuse light). Early morning sun or late evening sun is fine. I use a 50% shade cloth in the summer for the mid day sun, but try to let some full, natural sun in under the cloth in the morning. In the winter, the shade cloth comes off because my New York winter sun is weak at best
You can also use artificial lighting – when selecting a light bulb, you have to keep two things in mind – brilliance (measured in foot candles or lumens) and color temperature. Generally speaking, with artificial lights, you can’t get a bulb too bright. With that in mind, it is better to go with compact fluorescent fixtures as they produce more light per watt of electricity than standard fluorescent fixtures. Try to find a bulb with a color temperature between 4000 and 6500 K. 5000 is optimum, but bulbs of this temperature are hard to find. Plants should be about 6” to a foot under compact fixtures, and closer for standard fixtures. I have used both standard, 4’ twin tube fixtures and the compact ones, and I definitely see better results with the higher light levels from the compact fixtures – also, you can fit more of them in the same space to get even MORE light.
Nepenthes, as with most carnivorous plants, have evolved their carnivorous trait in response to the environmental pressure of poor soil. Highland Nepenthes (and most lowland, for that matter) prefer loose, open media (similar to orchids). I used to use pure long fibered sphagnum (LFS for short), but I have found better results by introducing orchid mix (bark, charcoal, pumice…I buy the pre-mixed orchid mix from Schultz) into the mixture. I generally go about 2/3 LFS and 1/3 bark mix. This soil mixture allows water to wash through so air can come back in to the roots; however it still holds enough moisture to keep the plants happy.
Some people also use coconut husk and coir in their mixes, but these are subject to contamination (mostly from salt), so should be rinsed thoroughly before use. You should experiment with different media mixes to see which work best for you.
Nepenthes, being tropical jungle plants, generally prefer to be moist. However, as mentioned in the media section, they do appreciate air in their roots, too, which means that you should not keep them soaking wet all the time. The best bet is to keep the media moist by watering every 2 or 3 days, and letting the water run through.
A note on the water: You should not use tap water unless you have VERY pure water (or a very good water filter, like reverse osmosis). Tap water generally contains salts, chemicals and lots of dissolved solids that can build up in the soil media, and eventually stunt or even kill your plant. So try to use rain water, reverse osmosis filtered water or distilled water as much as possible.
Here is where you’ll find the greatest variability in the cultivation requirements in highland nepenthes. Some, N. ventricosa for example, even though technically highland species, will do very well even in lowland conditions. Others swing the other way and are considered “ultra” highland – these species will wither and die very quickly if not kept cool.
General temperature requirements for highland species are as follows: high 70’s to high 80’s in the day, mid 40’s to upper 50’s at night. However, because of the above mentioned variability, you have to know a little about the species you wish to cultivate. If it comes from really high up the mountain (“ultra” highland), night temps can go as low as the 30’s, and shouldn’t be higher than 45. Some people actually put these guys in the fridge overnight! These varieties also need to have their days kept a little cooler, generally not over 80.
ALL Nepenthes grow best in high humidity. Some varieties adapt very well to lower levels…..and some don’t. Highland nepenthes are generally more forgiving of daytime drops in humidity so long as it gets really humid at night. But it’s still better to keep the humidity up all the time. Days at least 70% and nights over 80% is optimum.
Also, Nepenthes are creatures of habit. They like a stable environment. Humidity fluctuation should be avoided if possible (day to day, that is….if every day is 75% and every night is 85%, that’s not considered fluctuation).
Combine these factors, and unless you live somewhere with constantly high humidity, you are better off either growing them in a greenhouse or in a terrarium. Now, don’t panic. There are plenty of species and hybrids which do adapt very well to less than stellar conditions. N. ventricosa, as I mentioned above, will grow well just about anywhere (I have one growing out of control on my front step). Every species is a little different. If you follow these guidelines, though, you can grow just about all of them.
To avoid mold and fungus in this necessarily highly humid environment, you should try to get some air circulation around your plants – don’t seal the terrarium completely, or, as some people I know do, you can rig up a computer fan in the tank (I just leave the tank about 10% uncovered, and it seems to do the trick). In a greenhouse, an oscillating fan is useful.
It is generally not necessary to fertilize neps – though it’s fun to FEED them. Remember, these are carnivorous plants, so they have evolved to absorb their required nutrients from their victims. Feeding plant will help if grow better.
However, if you grow your plants in a tank, or you simply don’t have a lot of insects flying around, you certainly can fertilize your Nepenthes. The rule of thumb is to use orchid fertilizer, but mix is ½ the recommended strength for orchids – also, you would only do this once a month instead of three times.
You can also use slow release fertilizer like Osmacote – again, however, you have to use much less than the recommend dose. Too much fertilizer will burn a Nepenthes’ roots. You can also find slow release fertilizer specifically for Nepenthes at online nurseries like the Black Jungle.
Can I still grow Nepenthes if I can’t do all of this?
Yes, you can. As I mentioned a few times, these guidelines are for optimum conditions, which only truly picky plants require. There are many species (and generally most hybrids) which will tolerate higher light (if “tanned” slowly), less frequent watering (so long as you don’t let them get bone dry), lower humidity (not TOO low – 30% is the lowest even my toughest plants have been able to grow in) or higher night time temps. I wouldn’t suggest being TOO experimental with potting media – regular potting soil is just a bad idea.