11 Aug

HOW TO GROW NEPENTHES?

In this article dedicated to the magnificent carnivorous plants of the genus Nepenthes we will delve together into all the highlights for a good cultivation of this tropical carnivorous plant without overcomplicating life so that you can rejoice in the lush growth and be able to admire the formation of new leaves and traps in bright shapes and colors!

Yes! Being a tropical carnivorous plant Nepenthes needs more care than Dionaea, Sarracenia and the more hardy sundews. So it is worth knowing them and especially knowing the key points for growing Nepenthes as it may seem difficult, but difficult it is not!

Many neophytes or inexperienced enthusiasts are impressed by this magnificent carnivorous plant that goes by the name of Nepenthes, unfortunately in the absence of experience and basic knowledge experiments do not always have a positive result, giving rise to the belief that these are difficult plants to grow and therefore many throw in the towel right away. That is why it is worth investing 10 minutes to learn about these carnivorous plants, their habitat and how to take care of Nepenthes in an article that aims to divulge basics and small tricks to not make mistakes and easily grow this carnivorous plant!

Nepenthes is a tropical, semi-climbing carnivorous plant belonging to the Genus Nepenthaceae, generally they find their ideal Habitat among the rainforests and montane forests of the Malay Archipelago, Borneo, New Guinea, Indonesia, the Philippines and Western Australia where they grow by using the tendril that connects the leaf to the ascidium to “cling” to the surrounding vegetation and grow taller (some can reach up to 15 meters in height). Some species can also be seen in Madagascar, Sri Lanka and parts of India and China.

Nepenthes is a predominantly terrestrial carnivorous plant that sinks its delicate roots into nutrient-poor, inert organic-rich, draining and very light soils. Therefore, as with all carnivorous plants, the scarcity of essential nutrients at the root level has led these plants to develop exceptional adaptations in order to live in a decidedly harsh environment.

I speak of exceptional adaptations in that Nepenthes are not limited to catching insects or small animals, over millions of years of evolution they have created a special bond with the environment and the animals that inhabit their own Habitat. In fact, some Nepenthes are “detritivores,” meaning that they are able to exploit organic waste (e.g., fallen leaves from other plants) for their own benefit. Others, such as the famous Nepenthes lowii , produce an exudate on the inner page of the operculum of the ascidium. This substance turns out to be very sweet and to have a mildly laxative effect on small rodents and birds that are attracted to such nectar and will unconsciously use the ascidia as a toilet.

After a brief introduction on habitat it is absolutely necessary to divide the genus Nepenthes into two main categories, namely, Nepenthes lowland and Nepenthes highland. As already mentioned they are carnivorous plants that find their ideal environment in rainy tropical mountain forests.

So what do lowland and highland mean?

These are two terms that are used to define the altitude at which they live, this is because between a lowland and a highland environment there is a significant difference in terms of temperature and environmental conditions. Therefore, the various species of Nepenthes have evolved by adapting to these conditions that are strictly necessary for their growth. This means that a lowland Nepenthes is unlikely to adapt to a highland environment and vice versa.

However, most Nepenthes (especially a great many hybrids between the two categories) we can say are intermediate, that is, adaptable to a middle ground between the two extreme conditions, so no fear!

It is compulsory for us to briefly acquaint you with these conditions so that you can best learn about the Nepenthes genus and consequently choose the plant that is right for you and be able to care for it in the best possible way.

LOWLAND CONDITION

We define by the term lowland those environmental conditions that we can find in mountain forests located from the “base” of the mountain up to an elevation difference of about 1000 meters.

In this environment, temperatures are generally constant, not less than 20°c and not more than 30°c.

The most common Nepenthes lowland are:

INTERMEDIATE CONDITION

In the range of Nepenthes growing in intermediate conditions, i.e., a “middle ground” between the two extremes lowland and highland we can include all those Nepenthes that find their ideal habitat at an elevation difference between about 1000 m and 1500 m.

It should be specified that many of these Nepenthes have also been found at lower or higher elevations as well as Nepenthes growing at the two “extremes” have also been found in intermediate conditions (e.g. N. maxima, N.ampullaria, N.rafflesiana and others).

In addition, most artificial hybrids between Nepenthes lowland and highland grow perfectly in intermediate conditions.

Temperatures at these elevations are generally between 20°c and 25°c during the day and involve a slight temperature change at night
where temperatures can drop to around 16-18°c.

The most common species of intermediate Nepenthes are:

HIGHLAND CONDITION

Purely mountainous conditions where the elevation difference falls between 1500 m to over 2500 m.

In this environment temperatures do not exceed 22-25°c and there is a temperature swing between day and night temperatures that can be more than 10°c although generally night temperatures do not fall below 15°c.

The temperature swing for Nepenthes that obligatorily live in a highland environment is absolutely necessary to ensure their growth.

The main Nepenthes that grow in these environments are:

Having finished this brief introduction to the habitat of plants belonging to the genus Nepenthes, we will look together at the essentials of how to best cultivate this spectacular carnivorous plant that can provide enormous satisfaction.

A. Sun exposure

Nepenthes is a carnivorous plant that tolerates little direct sun, especially during the hottest hours of the day.

Why do they avoid direct sun?

Because in the wild they live within rainforests where the sun is masked and sunlight filtered by taller plants.

So where should I place my Nepenthes?

For all Nepenthes, it is ideal to place them in a shady area (porch, porch, under large trees..) or by using shade cloths. If the humidity is high enough, direct sun in the early morning hours or the late afternoon hours will not be a problem.

B. Water

Nepenthes poorly tolerates waterlogging, so you should keep the soil moist at all times, but never soggy with water.

In summer when temperatures are extreme, you can leave 1-2 cm of water in the saucer until it is absorbed. This is because evaporation is usually fast enough to prevent any stagnation.

Use only distilled water. Alternatively, all waters that have an extremely low mineral salt content are suitable. For example, all condensation water (air conditioner, dehumidifier). The conductivity of the water should have a value of less than 50 micro-siemens.

Why should stagnant water be avoided?

In their habitat the soil is very draining, so water percolates downward. For this reason, it is extremely rare for there to be water stagnation.
In response, stagnation would cause lack of oxygen in the soil, this condition results in root asphyxia and as a result the delicate roots of Nepenthes would rot irreparably.

Why distilled water?

There are several reasons, but let’s try to think in terms of environment.
Nepenthes grows in an extremely rainy environment, on a draining soil of mostly inert nature, what does this entail?

Simply that the mineral salts and most of the nutrients in the soil are constantly washed away by rain, which by its nature does not contain minerals.
For this simple reason, the root system of Nepenthes has adapted to receive very little nutrients from the soil.

An essential point for good results is to ensure high air humidity because as mentioned above, Nepenthes grows in rainfed environments where rain is very frequent and therefore humidity is very high.
Lack of humidity would damage the leaves irreparably.
However, it is necessary to ensure good air recirculation to avoid fungal diseases that could arise in high humidity situations.

How can I solve this problem?

Let’s not panic because there are many solutions! Let’s start with the assumption that many of the easiest Nepenthes to grow make do with a generous sprinkling of distilled water 2-3 times a day all over the plant. If you decide to grow indoors, for example, inside a semi-enclosed terrarium, the problem is practically solved at the outset since the relative humidity of the air inside a terrarium is sufficient, although it is still good to spray profusely if leaves from time to time.

Alternatively, many growers use misting or fogging systems (i.e., recreating fog with more or less inexpensive tools) especially inside large terrariums, growrooms, or greenhouses.

The use of misting systems is very useful when growing Nepenthes highland, because these systems help to bring down temperatures thus avoiding too high temperatures during the day and at dusk by also helping to create the necessary temperature change. (Note: these systems alone help but do not guarantee ideal conditions, for best results fans, extractors, water cooling systems, air conditioners, etc. are usually used).

C. Substrate

While 50% peat and 50% perlite is fine as a general substrate, consequently even for Nepenthes it creates no problems, many growers use mixtures in various proportions of peat, perlite, bark, akadama, dry/live sphagnum.

In my experience a mixture of 60 percent perlite and 40 percent peat with the addition of live or rehydrated sphagnum moss to wrap the roots and give a little extra moisture, turns out to be a good compromise for beginners struggling to find certain materials.
Personally, I have had the best results by mixing rehydrated dry sphagnum moss and perlite in equal proportions, always adding live sphagnum moss around the base of the plant.

CAUTION: Do not breathe in unprotected perlite dust, moisturize it properly before handling it, it is a very fine dust and harmful to our lungs!

Why such light soils?

Because Nepenthes needs moisture, but it also needs very aerated soils to avoid root rot problems. Consequently, it is good that the soil does not have too much peat or material that can “pack down.” It is therefore preferable to increase the proportion of perlite or possibly add other materials that are always inert with a thick and suitable grain size so that the roots can “pack up,” while still remaining well aerated. In addition, it is essential that the substrate be free of nutrients, as in the long run they would be detrimental to Nepenthes, which, although more tolerant than other carnivorous plants, may no longer develop ascidia and in the long run would inexorably lead to the death of the plant.

Can I fertilize my Nepenthes?

It is always a good idea to avoid fertilizing all carnivorous plants, including Nepenthes.
However, it is possible from time to time to fertilize Nepenthes (this genus of carnivorous plant only) with very dilute doses of orchid fertilizer or any generic foliar nutrient, as long as you follow three rules:

• dilute the fertilizer-fertilizer to 1/3 or 1/4 share
• spray the product only on the leaves
• give the product 10 to 15 days apart

D. Winter

Nepenthes do not go into vegetative rest! Being tropical plants they vegetate all year round but only under constant conditions.

Solutions to ensure more or less constant conditions all year round are different depending on the type of habitat they belong to, i.e. whether Nepenthes lowland, intermediate or highland.

To solve this problem, it is necessary to ensure dry soil and relatively low air humidity.

Let us try to clarify in more detail.

• Lowland: ideally, you should have a terrarium or growbox with stable conditions all winter as many of these Nepenthes (especially the ultra lowland ones, i.e., the most “delicate” ones) begin to show signs of suffering already around 18-20°c. However, it is possible to “overwinter” them indoors as long as they are placed in a well-lit room where temperatures are not prohibitive for them or in a double window under the same conditions.
• Intermediates and highland: as they need generally lower temperatures than lowland they are well adapted to spend the winter inside a double window or even in a terrarium or growbox as long as you can ensure a minimum of temperature change and temperatures never drop below 15°c

If you decide to make the indoor-outdoor move i.e., grow Nepenthes outside in summer and inside in winter, it is important to move the plants at the time most suitable for them. That is, when outdoor temperatures (especially night temperatures) are balanced to indoor temperatures so as to avoid overstressing the plant.

E. E. PESTS AND DISEASES

Nepenthes are hardy plants that are rarely affected by pests, however, if grown near diseased plants or plants with ongoing pest infestations it is possible that Nepenthes will also be attacked.

The main pests, fungi and diseases that can affect Nepenthes are:

• Aphids: small stinging insects generally light green, black or white, a few millimeters in size and equipped with wings. Aphids suck sap especially near the meristematic apex causing leaf deformity.
  They are easily eradicated manually or by using one of several commercially available organic aphicides, repeating the treatment after 10 days as these pests produce treatment-resistant eggs.
• Mites: commonly called the red spider mite, it is a microscopic pest and therefore impossible to see with the naked eye. It creates similar damage as aphids however it is difficult to recognize with the naked eye as the symptoms are similar to those caused by aphids, stress from too much heat, or other pests.
  A plant acaricide can be used for treatment, and as with aphids, it needs to be repeated a few days apart.
• Mealybug: It is rare for one of several types of mealybug to attack Nepenthes. This usually happens when the plant is placed in close proximity to other plants with severe infestations going on. You can remove mealybug manually or by using a systemic plant insecticide.
• Cercospora: This is a disease caused by a fungus and can occur in spring or fall when humidity is too high. It is not a lethal disease but creates small brown spots on the leaves outlined with purple-red. It therefore creates an unsightly effect but is a disease that is easily eradicated with one of several appropriate products on the market.
• Powdery mildew: also called “white mildew,” this is a disease caused by a fungus and can occur in spring or fall under conditions of high humidity and poor air circulation. It appears as a white, “powdery” patina that attacks various tissues of Nepenthes plants, which generally manage to respond well and fight the disease on their own. If the disease is prolonged, however, various problems can arise, and it is therefore advisable to treat right away with one of the good specific products on the market.
• Anthracnose: This is an insidious fungal disease that is difficult to combat if not treated promptly. Recognition is rather difficult because it is easily confused with burn stress as it presents with the formation of dark spots on leaves and stem that rapidly enlarge leading to areas of desiccation. It arises under conditions of poor ventilation and high humidity. Plants that are infected with anthracosis will need to be periodically treated with antifungal products as they will often be prone to relapse.
• Pythium: This is a fungus that is normally present in the soil, however, it can become pathogenic under conditions that make its proliferation uncontrolled (e.g., rotting substrate, irrigation with non-quality water). This pathogenic fungus is probably the most fearsome for plants of the Genus Nepenthes as it attacks the roots and if not eradicated in time with appropriate products it will irreparably damage the root system compromising its ability to absorb water and causing the death of the plant.
• Heat and cold stress: in these cases you must be prompt because Nepenthes poorly tolerates too high or too low temperatures that cause burning in the leaves, wilting and blackening of the meristematic apex (critical condition). In addition, if the plant is exposed to direct sun, it may burn irreparably within a few hours . Because of the delicate tissues, damage caused by prohibitive temperatures may be irreparable even after a very short time ( a few hours!). The only way to avoid such damage is to be preventive.

F. Vacations

How should one behave when one is away for some time?

The most common method is to entrust the plants to friends/relatives who, however, in the absence of experience or knowledge of Nepenthes might cause more harm than good, but no fear! Just take some small precautions: educate those in charge well.

Joking aside the methods are different, but as Nepenthes is a plant that does not tolerate water stagnation I strongly advise against the classic “raft” systems. , however there are also other simple solutions to care for one’s plants from a distance:

• Aquagel : this is an inexpensive product that you can buy in any well-stocked garden center, it is a tube filled with a gelatinous liquid that is free of harmful substances. Just apply the tube directly to the substrate following the instructions on the label and you’re done!
• Bottles with a slow-release system: another system similar to aquagel but involving the use of a bottle of water usually connected to a porous dispenser. This product is also readily available.
• Automatic drip/rain watering system: expensive but effective, this is an electronic system that can be connected to external containers filled with water (the cheaper ones connect to the home water supply but as we know we need distilled or rainwater). A timer allows us to decide how often to water the plants.

CONCLUSION:

The world of Nepenthes is diverse and fascinating, the purpose of this article is to introduce the new enthusiast to the cultivation of the carnivorous plant Nepenthes starting from their habitat to understand their basic needs, the most common problems and how to take care of them following general guidelines to avoid stress and enjoy the enormous satisfaction that this magnificent plant is able to give.

For more on trapping methods, flowering and possible pollination, and other curiosities about the Genus Nepenthes, more articles will follow soon.

G.Mehle / V. Guidolin

G.Mehle / V. Guidolin