Known also as Asian pigeonwings, bluebellvine, and Darwin pea, butterfly pea's amazing blue hue provides a pop of vibrant color in the garden and some magic in the kitchen!
Hailing from equatorial Asia, the plant’s native range encompasses the Indian subcontinent as well as Southeast Asia, but its botanical name, Clitorea ternetea, originates from the Greek word kleitoris, referring to the shape of the flower. Today, this exotic plant is having its moment in the spotlight, thanks in part to its properties as a natural food coloring — one that can turn from bright blue to pink in seconds!
The Story of Butterfly Pea
Butterfly pea has a mild, floral flavor and a most intense natural color. This distinct true blue, actually quite rare in the plant world, makes it a very popular choice as a natural blue food coloring, so most recipes that include butterfly pea play on its wild pigments and rely on additional ingredients for an added depth of flavor.
Southeast Asian cuisines have long used the flower in this manner. In Malaysia, the blue petals are added to glutinous sticky rice to make a traditional dish called pulut tai tai. In Thailand, cooks will batter butterfly pea blooms in tempura and fry them.
Perhaps the most well-known preparation is dok anchan, or Thai butterfly pea tea. The blooms are steeped into a soothing and mild tea, usually flavored with lemongrass.
The blue color of its petals is an indication of an antioxidant called anthocyanin. This is the same antioxidant pigment that gives blueberries and beets their distinct deep color. Even more fantastic is the "magical" color change that transpires when citrus or another acidifying element is added to butterfly pea dye. With pH change, the color of the anthocyanin turns from sapphire to magenta and light pink as it becomes more acidic.
Many Asian recipes featuring butterfly pea recommend tossing a few blooms in with your rice while cooking, then removing the spent heads when they've exhausted their color, and this method does work well. Additionally, you can render the dye from the blooms by pouring hot water over them and straining the liquid. We love to make bicolored noodles — half dyed blue and the other half pink for a fun color contrast.
How to Grow Butterfly Pea
Butterfly pea is a tropical perennial that can be grown as an annual in cooler climates. It's most commonly started from seed, which is generally the easiest way to propagate it. The butterfly pea has a reputation as a spotty germinator, thanks to its thick, waxy seed coat, which makes it tricky for the peas to absorb enough water to begin germination. To improve germination rates and speed the sprouting process, simply nick the seed coat and soak seeds in warm water 24 hours before planting. Seeds should germinate in three to six days after planting.
As a tropical legume, the seeds germinate best in warmth (they will not tolerate frost) at around 86°F. Southern gardeners can sow seed directly, while gardeners in the north will need to start seeds indoors, where the temperature can be controlled, and transplant after all chances of frost have passed and the soil is warm enough.
Once planted (space plants 12 inches apart) keep the area free of weeds until the seedlings establish themselves (at about 4 to 6 inches tall). After that, the plants become quite robust and can tolerate drought, heavy moisture, and competition from weeds. Butterfly pea tolerates a range of soil conditions, except waterlogged spots (the roots do not like sustained standing water). Plants prefer full sunlight; however, gardeners in more tropical locations can allow for some partial shade. Allow the plants to trail freely along the ground unsupported or train them up a structure such as a trellis or stakes.
The twisting and twining habit of butterfly pea vine inspires many landscape ideas. Planted at the base of a structure, the vines readily cling and climb, making them excellent options for brightening or masking unsightly fences or walls. (Keep in mind, though, that this eagerness to climb can sometimes become unbridled and aggressive.) Vines scrambling across a fence or trellis or twining up an intricate arbor provide a pop of true-blue flowers with white-yellow centers.
Butterfly pea plays well with others in containers or directly planted in the garden. In the landscape, the flowers complement other tea plants, including the fragrant spikes of tulsi flowers or chartreuse tufts of lemongrass.
Butterfly pea is especially at home in a children's garden, and it's a great way to engage kids in gardening. Plant the vines to create "walls" or a "roof" of an outdoor play space and harvest the flowers to experiment with their wondrous color-changing properties.
The Uses of Butterfly Pea
While the vines of butterfly pea ignite the garden in a conflagration of color, below ground the plant helps to improve soil fertility in true legume fashion. Butterfly pea has been used as a cover crop for its ability to grab nitrogen from the atmosphere and transform it into a usable green manure, helping to enrich the soil with one of the most essential plant nutrients.
Home gardeners can easily harness the butterfly pea’s natural nitrogen-fixing abilities. Identify an area of your landscape with poor, nitrogen-deficient soil and plant your vine there. You can also incorporate butterfly pea into your crop rotation to prevent nutrient depletion, especially after a planting of heavy feeding crops, such as corn or cucurbits like squash.
Butterfly pea’s medicinal use has its roots in Ayurvedic medicine, dating back hundreds of years. In Southeast Asia and China, the roots, seeds, and leaves of the plant are used as a brain tonic to promote memory and intelligence. In traditional medicine, the fresh root is also employed to help ease conditions like tuberculosis, ulcers, and asthma, and juice from the root can be taken to eliminate phlegm.
Its potential medicinal properties are a subject of current research as well.
Butterfly pea contains vitamins and minerals like calcium, magnesium, potassium, zinc, iron, and manganese. One study found that the antioxidants present in butterfly pea flowers relax the nerves to aid in sleep.
Researchers are also interested in its potential for reducing inflammation, helping to prevent heart and brain disease, and aiding weight loss. A study of diabetic rats, published in the Journal of Applied Pharmaceutical Science, found that butterfly pea extract reduced their serum glucose levels, leading researchers to conclude that the extract showed anti-diabetic properties similar to a common drug (glibenclamide) to treat Type 2 diabetes.
Butterfly pea tea has few side effects, but it can cause upset stomach and nausea in sensitive individuals. As with some plant-based preparations, butterfly pea flower tea may interact with certain medications.
Butterfly pea has become a staple and a favorite in the Baker Creek gardens for its lovely, prolific blooms and its novelty as a culinary ingredient.
Key Takeaways
- Butterfly pea (Clitoria ternatea) originated in equatorial Asia. Its native range encompasses Southeast Asia and the Indian subcontinent.
- Asian cuisines have long used the blooms to color food and make tea, the best known of which is dok anchan, Thai blue butterfly tea.
- Butterfly pea's medicinal uses are rooted in Ayurvedic medicine, where its uses include promoting brain health and memory.
- Butterfly pea blooms are antioxidant rich and contain vitamins and minerals such as calcium, magnesium, potassium, zinc, iron, and manganese. Modern medicine continues to explore its potential.
- As a legume, butterfly pea also has powerful nitrogen-fixing properties, making it a very useful plant for soil improvement.
NOTE:
This story from the Baker Creek archives appeared in an edition of The Whole Seed Catalog and was written by horticulturist Shannon McCabe.
