The term “tentacle plant” refers to the fascinating group of carnivorous plants known as sundews, belonging to the genus Drosera. These captivating plants are admired for their unique appearance and intriguing prey-capturing method. Their leaves are adorned with glistening, sticky droplets, giving them the appearance of being covered in morning dew.
The Carnivorous World of Sundews
Sundews are a diverse genus within the Droseraceae family, encompassing over 194 known species found on every continent except Antarctica. Their defining feature is leaves equipped with numerous glandular tentacles. These tentacles secrete a sticky substance resembling sparkling dew drops, an alluring trap for insects.
When an insect, attracted by the glistening “dew,” lands on a sundew leaf, it becomes ensnared in the sticky mucilage. The tentacles then curl inwards to bring the prey into maximum contact with digestive glands. This movement, which can take minutes to hours depending on the species, ensures the insect is fully enveloped. Enzymes are then released to break down the soft tissues of the insect, allowing the plant to absorb essential nutrients that are scarce in their natural bog and fen habitats.
Cultivating Your Tentacle Plant
Light
Most sundew species thrive in bright, direct sunlight, requiring at least six to eight hours daily for vibrant coloration and robust dew production. Insufficient light results in pale leaves and reduced sticky secretions. For indoor cultivation, placing sundews in a south-facing window is ideal, or supplementing natural light with artificial grow lights provides necessary intensity. When using grow lights, positioning them a few inches above the plants helps ensure adequate light exposure.
Water
The type of water used for sundews is important due to their sensitivity to minerals. They require mineral-free water sources such as distilled water, rainwater, or reverse osmosis (RO) water. Tap water, which contains dissolved minerals and salts, can accumulate in the soil over time and harm the plant. A common watering method is the tray method, where the pot sits in a saucer filled with about half an inch to an inch of mineral-free water, allowing the soil to absorb moisture from the bottom. The soil should remain consistently moist but not waterlogged.
Soil
Sundews naturally grow in nutrient-poor, acidic environments like bogs, so their potting medium must mimic these conditions. A suitable soil mix consists of a blend of sphagnum peat moss and an inert, well-draining material like perlite or horticultural sand, usually in a 1:1 or 2:1 ratio of peat to perlite. It is important to avoid standard potting soils, compost, or any mixes containing fertilizers, as the added nutrients are detrimental to sundews.
Humidity
Many sundew species, especially tropical varieties, benefit from high humidity levels, ranging from 40% to 70%. Adequate humidity helps the plants produce abundant sticky dew on their tentacles. In drier indoor environments, methods to increase humidity include placing the potted plant on a pebble tray filled with water, ensuring the pot does not sit directly in the water. Terrariums can also provide a humid microclimate, though good air circulation is still important to prevent stagnant conditions.
Feeding
In their natural habitats, sundews efficiently catch insects to supplement their nutrient intake. For indoor plants that lack a steady supply of prey, occasional supplemental feeding is beneficial. Small, live insects like fruit flies or gnats are suitable, or freeze-dried insects can be used. It is recommended to feed only a few insects every few weeks, and to avoid feeding human food or too much, as this can overwhelm the plant. The plant’s carnivorous adaptations allow it to thrive even without frequent feeding, as long as light and water requirements are met.
Popular Sundew Varieties
Several sundew species are popular among growers due to their striking appearance and relative ease of care. The Cape Sundew (Drosera capensis) is a widely cultivated variety, known for its long, strap-like leaves and vibrant red tentacles, often producing numerous pink flowers. Drosera aliciae, or the Alice Sundew, forms rosettes of broad, spoon-shaped leaves that can develop reddish hues in bright light. Drosera spatulata, also known as the Spoon-leaved Sundew, is a compact species with small, spatula-shaped leaves and is prolific, often self-pollinating and producing abundant seeds. Another type is Drosera adelae, the Lance-leaved Sundew, which features long, narrow leaves and prefers slightly more indirect light. These varieties offer a good starting point for those new to growing sundews.
Troubleshooting and Beyond
Growers may encounter issues with their sundews, such as a lack of dew production. This is often a sign of insufficient light, improper water quality with mineral buildup, or low humidity. Increasing light exposure, ensuring the use of mineral-free water, and boosting humidity often helps restore dew. Browning leaves can indicate too much direct sun for certain species, low humidity, or mineral burn from tap water. Addressing these environmental factors can help the plant recover.
Some temperate sundew species enter dormancy during cooler months, forming a compact, resting bud known as a hibernaculum. During this time, growth slows significantly, and watering should be reduced, though the soil should not be allowed to dry out completely. This dormancy is a natural part of their life cycle and not a sign of distress. Sundews can be propagated through various methods, including seeds, leaf cuttings, or root cuttings. Leaf cuttings, where a portion of a healthy leaf is placed on moist growing medium, are a common way to produce new plants.