Nepenthes: how to grow & care for tropical pitcher plants

We are fascinated by the tropical pitcher plant and its unusually carnivorous diet. Here are some tips on how to keep them indoors.

The tropical pitcher plant (Nepenthes) absorbs nutrients from the soil, but also from insects that land in its traps. This is one of the reasons why it is an increasingly popular houseplant. Would you like to keep a carnivorous Nepenthes plant in your home? Read on for our top tips on how to grow a healthy Nepenthes indoors.

Pitcher plant: flower, origin, and characteristics

The tropical pitcher plant (Nepenthes), also known as the monkey jar plant or monkey cup plant, is the only genus in the pitcher plant family (Nepenthaceae). To date, more than 100 different species are known, some of which grow as semi-shrubs and others look like vines that cling to other plants with their tendrils. New species are still being discovered and new hybrids bred, including most of our hardier houseplants. Pitcher plants are native to Southeast Asia, but some species also come from India, Australia, and Madagascar. Nepenthes is mainly found in the ever-humid tropics and can grow at a wide range of altitudes. Depending on their place of origin and temperature preferences, a distinction is made between highland and lowland species. The leaves of Nepenthes consist of three parts: the leaf-shaped part, a tendril that emerges from the leaf used to cling on to other plants, and the cup-shaped trap at the end of the tendril. The flowers, which are arranged in clusters, are never actually seen in our houseplants.

Nepenthes is carnivorous, or in other words, a flesh-eating plant. Their cups are passive pitfall traps that attract their prey with scent or colour. The rim of the cup contains nectar. If the prey then settles on the rim of the cup, it can easily fall in, where it is unable to climb up and out of the slippery walls. At the bottom there is a highly acidic liquid with a pH value of 3 in which the prey is digested. After about three months, the trap withers. The lid of the cup is fixed shut and serves as protection against rainwater, which could otherwise wash the prey out of the cup or dilute the digestive juice too much.

The most beautiful Nepenthes species

Here we will introduce you to some of the many different species of monkey jar plants. However, the plants available in shops are mostly hardy Nepenthes hybrids, meaning plants that have been created by crossing different species.

Pitcher plants from the warmer lowlands

These species prefer constant, warm temperatures between 20 and 35°C, and include:

• Nepenthes ampullaria: This popular tropical pitcher plant has quite small, rounded cups. Unlike most of its relatives, Nepenthes ampullaria gets nutrients from not only insects but also other organic material such as bird droppings.
• Nepenthes mirabilis: This species has elongated cups and is widespread in its natural habitat. The colour of the cups can range from green to yellow to red. As a lowland Nepenthes, it prefers constant, warm temperatures.

Pitcher plants from the colder highlands

These species are used to temperature fluctuations. In the wild, it is usually warm during the day at around 25°C. At night, the temperature drops to 10°C. Highland species are used to a high humidity of up to 90%. They include:

• Nepenthes macfarlanei: This Nepenthes has striking cup colouring. The yellow-green pots are bulbous and usually speckled with red. This highland species is native to Malaysia and can cope well with temperature fluctuations.
• Nepenthes aristolochioides: This tropical pitcher plant is another highland species but is native to Sumatra. The unusual cup shape with an opening on the side makes this species particularly popular. It was therefore collected on a large scale and is now considered endangered in its native country.

Planting Nepenthes: location and soil

Pitcher plants are quite particular about their living conditions, so you need to take a few things into consideration when choosing a location. However, with the right care, Nepenthes can develop magnificent cups that are also helpful in keeping flies at bay.

Tropical pitcher plant hybrids that can be purchased from us tend to be quite robust and have been bred from mid-altitude species. We recommend keeping a constant temperature between 20 and 30°C for these plants. Given that Nepenthes grows naturally in sparse forests, the plant prefers a bright location. However, avoid locations with permanent full sun, as the cups may suffer damage from too much intense light.

Nepenthes needs high humidity, up to 90%, depending on the species. Indoor pitcher plants are satisfied with a humidity of about 60%. Soil for the Nepenthes must be permeable and low in nutrients. To loosen the soil, mix in a little expanded clay, for example. The soil should also be slightly acidic which is why soil designed for carnivorous plants often has a high peat content. To avoid peat use, there are methods of making a soil from pine bark, perlite, and quartz sand. This also provides an acidic pH value, good aeration, and minerals.

A greenhouse or terrarium provides ideal conditions for Nepenthes pitcher plants. There it is much easier to maintain the right temperature and humidity. However, only small, compact species should be kept in a terrarium, otherwise it can quickly become cramped. Place the terrarium in a bright but not directly sunny spot, or you will need to use an artificial light source.

Recap: planting Nepenthes

• Location: Bright, without direct sun, 20-30°C, and high humidity
• Soil: Low in nutrients, permeable, and acidic
• Optimal conditions are easier to create in an indoor greenhouse or terrarium

Monkey jar plant care: top tips

Probably the biggest challenge in caring for pitcher plants is maintaining the high humidity. The Nepenthes should be sprayed regularly with rainwater, several times a day in summer. An automatic water sprayer, for example, can be used for this.

Feeding pitcher plants

You do not need to feed Nepenthes, as it gets all the nutrients it needs from its soil. Although there is nothing wrong with putting an insect in the pot from time to time, only feed one insect at a time, so that the plant does not have to digest too much at once. To start the digestion process, the insect should also be alive.

Watering and fertilising Nepenthes

Ideally, use rainwater or distilled water for watering. You can also use boiled tap water if necessary. Do not pour the water directly onto the soil, but onto the saucer. The plant will get the necessary water itself and this will also increase the humidity. Keep the soil moist but avoid both drying out and waterlogging.

The pitcher plant need not be fertilised. It has a fairly low nutrient requirement, which is met by its soil. If it needs further nutrients, the plant uses its traps to catch and digest insects. If the monkey jar plant does not have access to insects indoors, you can add a little liquid fertiliser to the soil two to three times per growing season. A fertiliser such as our Plantura Liquid Citrus Food is ideal. It provides Nepenthes with iron and magnesium, among other things, which is otherwise mainly absorbed from its prey.

Overwintering Nepenthes

In its native country, the Nepenthes plant does not experience a cold winter, so overwintering the Nepenthes plant indoors is actually quite easy. Leave the monkey jar plant in a warm, bright place. Because the air is dried out from the heating, it is important to ensure a constant high level of humidity. To do this, place the plant on a saucer filled with expanded clay, for example, and water regularly. Too little light and moisture can easily cause the monkey jar plant to dry out and inhibit its growth in winter, but the plant usually recovers in spring.

Pruning Nepenthes

Pruning Nepenthes is not usually necessary. Though, if you do cut the plant back, it will sprout again, given the right conditions. Remove, however, brown, dried, and dead parts of the plant so that the plant no longer wastes energy on them.

Repotting Nepenthes

Each Nepenthes species grows at a different rate. Repot slow-growing Nepenthes species every two to three years and fast-growing ones as often as once a year. You also repot the pitcher plant when the pot is fully rooted. Do this at the beginning of the growing season in spring.

Dried out cups: what to do?

It is quite normal for Nepenthes cups to dry out. In good conditions they last about a year before being shed. However, withered cups can also be the result of low humidity or too little light. In this case, place the plant in a brighter spot and put a glass over it to increase the humidity. Cut off already dried out cups or leaves so that the plant can direct its energy to the growth of new leaves.

Propagating the pitcher plant

The monkey jar plant is propagated using cuttings. To do this, cut off a 10 to 15cm long shoot from the central stem. As the cut is made between two leaves, the plant is “decapitated”, so to speak. To reduce the transpiration area, in other words, to limit water loss, cut all the leaves in half, except the top two. Then plant the cutting in Sphagnum moss or nutrient-poor and acidic soil, which you must keep moist. Place a plastic bag over the pot to increase humidity. Remove the bag regularly to avoid mould growth. After a few weeks, roots and new shoots should have formed and the cutting can be transplanted. Ideally, only propagate thriving pitcher plants and do this during the growing season so that the mother plant can also sprout again.

As Nepenthes never actually flowers in indoor cultivation, propagation of the pitcher plant from seed is only possible with purchased seeds. Nepenthes seeds should be fresh, as the germination rate drops quickly.

Are you fascinated by the carnivorous diet of Nepenthes? Check out these carnivorous houseplants.