The sundew (Drosera) is a mesmerizing genus of carnivorous plants recognized for their captivating tentacles coated in sticky, sugary mucilage. This glistening “dew” functions as a sophisticated trapping mechanism, luring and ensnaring small insects. Adapted to nutrient-poor bog environments, their specialized nature means their care routine deviates significantly from that of common houseplants. Understanding these unique needs is the first step in successfully cultivating these fascinating predators. This guide provides practical instructions for meeting the specific environmental demands of sundews.
The Critical Trio: Water, Soil, and Humidity
The root environment is a frequent point of failure for new growers because sundews cannot tolerate the mineral content found in standard tap water. They require only pure, mineral-free water, such as distilled water, collected rainwater, or water filtered through a reverse osmosis system. Dissolved solids in regular tap water can chemically burn the delicate roots and cause plant death.
The most effective watering strategy for nearly all Drosera species is the tray method, which mimics their natural bog habitat. This involves placing the pot in a shallow tray that always contains about one inch of pure water, allowing the substrate to constantly wick moisture upward. This consistent moisture keeps the roots cool and prevents the accumulation of toxic salts.
Standard potting mixes are unsuitable for sundews because they contain fertilizers and minerals toxic to the roots. The substrate must be nutrient-poor, typically consisting of a blend of sphagnum peat moss mixed with an inert aggregate like perlite or horticulture-grade silica sand, often in a 1:1 ratio. This combination provides the necessary aeration and moisture retention without supplying external nutrients.
While most sundews prefer high soil moisture, their humidity needs vary by species. Elevated air moisture generally helps maintain the sticky dew. Tropical species often benefit from humidity levels between 50% and 80%, achievable using a closed environment like a terrarium or a pebble tray. Temperate and subtropical varieties are more tolerant of lower humidity but still thrive with good air circulation.
Harnessing the Sun: Light Requirements
Sufficient light is paramount for the health and characteristic appearance of sundews, as they thrive in direct exposure. Light intensity directly controls the plant’s ability to produce the sticky mucilage that gives the genus its common name. Without bright light, the plants struggle to produce dew, compromising their ability to capture prey.
Adequate illumination also dictates the vibrant coloration that indicates a healthy plant; many species display deep reds and oranges when exposed to high light levels. In a home setting, a south-facing window receiving several hours of direct, unfiltered sun is the most suitable natural placement. However, some species, particularly those with fine leaves, may require a slight buffer from intense afternoon heat.
When natural light is insufficient, artificial supplementation becomes necessary, especially during winter or in less sunny climates. High-output LED or fluorescent grow lights are effective alternatives, provided they emit high Photosynthetically Active Radiation (PAR) values. The plants require a photoperiod of 12 to 16 hours daily under these artificial sources to maintain robust growth and dew production.
A Natural Diet: Feeding Your Sundew
Sundews produce their own energy through photosynthesis, using sunlight and carbon dioxide. The insects they catch are not a primary energy source but supplement their diet with nitrogen and phosphorus. These elements are scarce in their native bog habitats. The nutrients are absorbed through the leaves after the prey is dissolved by digestive enzymes.
Plants kept outdoors usually capture enough prey on their own to satisfy their nutritional requirements throughout the growing season. However, indoor sundews, particularly smaller plants, may require manual feeding to achieve optimal growth rates and size. Feeding only needs to occur when the plant is actively growing and producing dew.
When manually feeding, select prey items small enough to be fully engulfed by the tentacles of the trap. Suitable options include rehydrated dried bloodworms, finely crushed fish flakes, or live flightless fruit flies, which are readily available from pet supply stores. These items should be placed directly onto the mucilage of a few tentacles. Feeding once every two to four weeks is sufficient to promote vigorous growth.
Seasonal Adaptation: Understanding Dormancy
The care routine must account for the plant’s geographical origin, as this determines whether it requires dormancy. Tropical species, such as Drosera capensis and Drosera spatulata, originate from regions with consistent year-round climates. They do not require or tolerate cold temperatures or seasonal rest. These plants should be maintained with consistent light, water, and temperature year-round.
Conversely, temperate species, including Drosera rotundifolia and Drosera filiformis, are native to regions with cold winters and survive by entering a dormant state. Dormancy is triggered by the natural decrease in both day length and temperature as autumn approaches. Attempting to skip this necessary rest period will lead to the plant’s exhaustion and eventual decline.
To prepare for dormancy, the plant forms a compact, tightly-closed winter bud known as a hibernaculum, signaling the start of the resting process. Growers must then facilitate a cold period by reducing watering and moving the plant to a cool location. The goal is to maintain a temperature consistently between 35 and 50 degrees Fahrenheit for three to five months.
If the refrigeration method is used, the hibernaculum should be placed in a sealed plastic bag with slightly damp sphagnum moss or peat to prevent desiccation. After the required cold period, the hibernaculum should be gradually reintroduced to warmer temperatures and brighter light to simulate spring. This management of the seasonal cycle is necessary for the long-term survival and health of temperate sundews.