No terrariums. No myths. No nonsense.
The cobra plant, Darlingtonia californica, is an awesome plant in person, and the second most requested plant from our customers after the Venus flytrap. When fully grown, its pitchers can tower 3 feet tall with heads the size of fists! But we'll be straightforward about it: Darlingtonia are finicky and one of the most challenging of all carnivorous plants. It prefers moderate summers, cool nights, well-drained soil, fresh water, and chilly winters. The cobra plant is not very forgiving of mistakes, so everything has to be just right.
If you’ve successfully grown Sarracenia and other outdoor carnivorous plants in the past, you will enjoy the challenge of Darlingtonia. If you’re new to growing carnivorous plants, gain some experience with other plants first. Get a handle on the basic elements of cultivation by reading The Ultimate Carnivorous Plant Guide for Beginners to learn more about growing some of the easier and more common plants in cultivation.
RangeDarlingtonia are native to remote montane streams and springs in Southern Oregon and Northern California. A few smaller patches grow in lowland streams along the Oregon coast, but the majority reside in the mountains. Those that are native to the mountains tend to be much more resilient to extreme temperature changes than those from the mild Oregon coast.
Where to GrowDarlingtonia grow best outdoors as a container plant on a sunny deck or patio. You may also grow it in a pond or fountain with flowing water, but keep the crown of the plant from being submerged. Because of its specific soil requirements, do not plant it in the ground.
SunlightProvide partial to full sun, four or more hours of direct sunlight, during the growing season.
Heat ToleranceDarlingtonia can withstand extreme heat. In the wild, we've seen Darlingtonia growing in 104°F weather. However, if daytime temperatures rise above 90°F, nighttime temperatures need to drop significantly, below 70°F, preferably in the 60s or 50s. Cool nights are essential for the overall health of this plant.
WaterYour watering method will be the most important factor in growing Darlingtonia. Soil aeration is vital for it. We highly recommend watering your Darlingtonia daily and allowing it to drain through completely rather than setting it in standing water as you would for Sarracenia. Daily watering mimics what Darlingtonia experience in the wild, where a constant, slow stream of cool water washes over its roots, cooling the plant and rinsing the soil of nutrients or organic chemical buildup.
On hot summer days, water your Darlingtonia in the morning and evening. If you have trouble remembering to water your plant daily, consider using a faucet timer with a drip system. If daily watering is not feasible, then use the tray method and keep your plant in small amounts of water, no more than 1/2 inch.
Darlingtonia is tolerant of relatively hard water, up to 150 ppm of dissolved minerals, so using pure water (under 50 ppm of dissolved minerals) isn't at all necessary as long as you're allowing the water to drain through. If you choose to set your plant in standing water, you should use pure water.
SoilOver the years, we've experimented with a variety of soil mixes. In the end, we found that a very simple mix of one part peat moss and two parts perlite was as successful as other mixes we used. You can top dress the medium with pea gravel or live sphagnum moss to prevent splash erosion with top watering. Change the soil annually to maintain optimal root health.
PotsThe ideal type of pot for a Darlingtonia is short and wide. Darlingtonia have short roots, so the container doesn’t have to be tall. However, because they self-propagate via long underground stolons, the pot needs to be wide. Because of their cold winter dormancy requirements, ceramic pottery, especially unglazed pottery, may be unfeasible as it tends to crack during freezes.
In our experiments, we discovered that plastic cat litter pans worked very well. They're wide containers than they are deep, with enough depth for Darlingtonia roots and enough width for the plant to comfortably spread. We used brand new pans from a local discount store. Along the sides of the pan, we punched small 1/4 inch holes about ½ inch from the bottom for drainage. Technically there will be sitting water ½ inch deep at the bottom of the pan, but as the surface area is ample enough and the soil relatively shallow, water will evaporate much faster. For a while, we grew the majority of our mother plants in these pans. If plastic cat litter pans are too unsightly, consider using wide plastic garden bowls.
Winter CareDarlingtonia require 3-4 months of winter dormancy triggered by cold temperatures (below 50°F or 10°C) and shorter daylight hours. While dormant, your plants can withstand overnight frosts down to 20°F (-7°C). As long as temperatures rise above freezing during the day, you don't need to protect them. However, even while dormant, plants will still need to sit in a small amount of standing water to prevent its soil from drying out.
If you live in zones 7 and 8, pay attention to weather alerts. If weather forecasts predict that daytime temperature will remain below freezing for more than a couple of days, you will need to protect your plants from frost burn, a type of dehydration that occurs during prolonged freezes. Cover your plants with a tarp or move them to an unheated enclosure. When the daytime temperature rises above freezing, you may uncover your plants and allow it to continue its dormancy as usual.
If you live in zones 6 or colder, areas where the temperature routinely drops below freezing for more than a week at a time, you will need to mulch your container plants for the winter. Maintain soil moisture whenever the temperature rises above freezing. Uncover your plants in early spring.