Methods of wintering carnivorous plants
One of the main tasks during winter is providing carnivorous plants with adequate conditions for successful dormancy. This allows them to rest and prevents exhaustion over the winter. Without a period of rest, most carnivorous plants that require cold wintering will eventually perish due to fatigue. Plants are moved to their wintering location (if grown outdoors) when the outdoor temperature aligns with the temperature at the wintering site. Below are some of the most common proven methods of wintering carnivorous plants:
This guide specifically concerns Dionaea muscipula (Venus flytraps), Winter-growing Drosera (sundews) with hibernaculum (Drosera filiformis, Drosera rotundifolia…), Sarracenia (pitcher plants), and Pinguicula (butterworts) with hibernaculum (Pinguicula grandiflora, Pinguicula vulgaris…).
Wintering in a cool room
This method is the simplest and most reliable. Plants are moved, as they are, to a cool location such as a basement where low temperatures are guaranteed. They should be placed as close to light as possible, ideally next to a window. Temperature should range between 5-10°C. The warmer it is, the more light the plants will need. Substrate must remain moist and must not dry out. Water in the saucer should be up to 1 cm high.
Wintering in a refrigerator
Another option is storing plants in the refrigerator. This method is suitable for people living in apartment buildings without access to a cellar or cold hallway. The refrigerator maintains a constant temperature below 5°C. At this temperature, plants stop growing completely and therefore don’t need light—they can remain in total darkness.
With a small number of carnivorous plants, they can be placed in pots directly into the refrigerator. The substrate must stay moist and must not dry out. Water in the saucer should be up to 1 cm high. Occasionally, it is necessary to inspect the plants and substrate, as the lack of air circulation increases the risk of mold growth. Mold on a small scale is manageable, but in more extensive cases, it can be disrupted with sprays of water or chamomile tea solution.
Alternatively, plants can be placed in sealed containers to save space. This involves removing them from the substrate and rinsing the roots to eliminate residual substrate (which may mold). Plants must be cleaned of dead traps and prey to prevent mold formation. Venus flytraps should have all closed traps trimmed, as they may contain prey. Pitcher plants can be fully trimmed. The roots are wrapped in a moist, unscented tissue and placed in a sealed container or zip bag. It is recommended to use a paper tissue rather than toilet paper, which tends to disintegrate when wet and becomes difficult to handle. These wrapped plants are then stored in the refrigerator’s vegetable drawer near the freezer. Periodic checks for mold are advised. A detailed guide with photos can be found in this link.
As a variation, instead of placing plants in a zip bag, they can be layered on live or dried sphagnum moss. The process is similar to the zip bag method, but instead of wrapping roots in a moist tissue, damp sphagnum moss is used as the base layer in a container, followed by cleaned plants, alternating with layers of moss—like making lasagna. Live sphagnum moss has natural anti-fungal properties, reducing the risk of mold. Plants must still be regularly inspected.
Wintering on a balcony
Another option is wintering plants on a balcony. It’s advisable to place the plants in a sealed polystyrene box to prevent the substrate from freezing and killing the plants. Pots are placed in the polystyrene box, which is then filled with insulating materials to minimize freezing (e.g., wood wool, polystyrene pellets…). If daytime temperatures exceed 5°C, the box lid can be removed to provide light. Before frost, the lid protects the plants. The substrate must remain moist and must not dry out. Water in the saucer should be up to 1 cm high.
Wintering in a warm room
This method is only a temporary solution and is not recommended as a reliable wintering method. It can be used for Venus flytraps and pitcher plants, but not for dormant plants from temperate zones. Venus flytraps and pitcher plants experience a significant lack of light under this method during winter. Proper summer care is essential for the plants‘ survival through winter. Artificial lighting can be provided to compensate for reduced light during the winter. Plants are grown as they would be during the growing season.
Wintering in an outdoor bog
If you grow carnivorous plants suitable for year-round outdoor cultivation in an outdoor bog, no additional care is required for winter preparation. Regular water checks are important to ensure the plants don’t dry out. In cases of persistent frost, the plants can be covered with fir branches to protect them and reduce the chances of damage.