You might have heard about carnivorous plants that feed on insects and arthropods. While some of them have pitfall traps (as in pitcher plants), some others like Venus Flytrap have snap traps. There are some carnivorous plants that suck in insects and some species use their sticky mucilage to catch their prey. Some of the well-known carnivorous plants are pitcher plants and Venus Flytrap. These plants are also popular as houseplants and are grown in gardens too.
It is a common fact that pitcher plants are carnivorous and they trap insects and other arthropods using pitchers, that are modified midribs of their leaves. These pitchers contain a fluid, in which the insects drown and die. Pitcher plants absorb nutrients from the insect, which gets dissolved in the liquid inside the pitcher. The disintegration of the trapped insects is either done by the bacteria inside the pitcher or through the action of the digestive enzymes in the liquid. In some pitcher plants, live insect larvae are found in the liquid inside the pitchers and these larvae feed on the trapped insects. In such cases, the plant absorbs nutrients from the excreta of the larvae. The carnivorous nature of pitcher plants can be considered an adaptation that compensates for the infertility of the soil, in which these plants usually grow. Pitcher plants are found to grow in soil that is poor in nutrients, especially nitrogen. So, suitable growing conditions is a must for these plants.
How to Care for Pitcher Plants
Most of the pitcher plant species belong to the families Nepenthaceae and Sarraceniaceae. While pitcher plants of the family Nepenthaceae are mostly climbers with pitchers formed at the end of the leaves' midribs, in case of plants in Sarraceniaceae family, pitchers are formed with the entire leaves. The plants in the latter family are not climbers, but grow on ground. The most popular pitcher plants grown in gardens are red pitcher plant (Nepenthes ventricosa), pale pitcher plant (Sarracenia alata), yellow trumpet pitcher plant (Sarracenia flava), purple pitcher plant (Sarracenia purpurea), Sarracenia Dana's delight, Nepenthes rajah and Nepenthes alata.
Where to Grow Pitcher Plants
Though pitcher plants can be grown outdoors as well as indoors, it is best to grow them outdoors. Soggy areas are ideal for growing these plants. The soil must be acidic in nature. If you don't have such a location in your garden, then plant them in pots (plastic or glazed ceramic ones) that do not drain. The potting mixture has to be 50% sphagnum peat moss and 50% perlite/horticultural sand. If you are using sand, make sure that it is clean and washed. You should not use beach sand, contractor's sand or limestone sand. The location must provide bright light and high humidity, which are necessary for the growth of the plant. Direct sunlight is also good for some species. It may also happen that too much sunlight can cause sunburns on the plant. If there is a deficiency of sunlight, the plant may become weak and lack color too.
Keep the Soil Soggy
Always keep the soil wet, but use distilled water or rainwater for this purpose. This is because, tap water may contain chemicals that can harm the plant. Bottled drinking water is not advisable, as it contains minerals. The easiest method is to keep the pot (with the plant) in a tray of water. For pitcher plants, you can keep a good amount of water in the tray. The water level in the tray can be deep enough to immerse half of the pot. For other carnivorous plants, the water level (in the tray) should be low, so that it does not cover more than half-an-inch of the pot. In such cases, refill only when the water dries up. For most of the carnivorous plants, watering means refilling the tray.
Humidity and Temperature Levels
Even though, pitcher plants can tolerate low levels of humidity, during summers (growing season), high humidity levels (60% and above) are required. It has been observed that in low humidity levels, pitchers are not formed. You can grow them in terrariums or greenhouses, for high humidity. In case of terrarium, there must be some sort of ventilation, to avoid fungal growth and other damage to the plant. Humidifiers can also be used for this purpose. The temperature requirement of pitcher plants may vary with the species. Most of these plants can grow well in a temperature range of 55-95° F. However, hybrid pitcher plants are considered easier to grow. Apart from that, colorful pitchers are available in hybrids like N. x Dyeriana, N. x Chelsonii, N. x Williamsii, N. x Ventrata and N. x Superba. It will be better to avoid those species that require extreme temperature for growth.
Feeding and Dormancy
While fertilizers are not usually needed by pitcher plants that have access to insects, others may require feeding in very small amounts, so as to maintain the acidity levels of the soil. This is done by using a foliar spray once during the growing season. Dilute the fertilizer (one teaspoon for one gallon of water) and spray on the foliage and not inside the pitchers. You should not put meat inside the pitchers, but, can use small insects like flies and crickets (occasionally) for this purpose. Usually, two to three insects per month is sufficient for the plant to thrive. Some people use Miracid fertilizer in diluted form. Mix one-eighth teaspoon of this fertilizer with a quart of water and fill three-fourth of the pitchers (and not the plant or soil). Pitcher plants are dormant during winters. In case of plants in the outdoor soggy areas, you can use three inches of pine needle mulch during late fall. You may also dig out the plant, remove the soil and dead leaves and keep it in a sealed bag with some moss. Refrigerate this plant for around three months, before replanting it.
The above mentioned are some generalized tips and guidelines about tropical pitcher plant care. Requirements of pitcher plants may vary with different species and hybrids. So, you must collect enough information about that specific pitcher plant species, that you intend to grow.