A purple butterfly pea gin cocktail is gin and fresh lemon juice shaken, poured over ice and topped with club soda, then finished with a splash of blue butterfly pea flower syrup that turns the whole glass purple as you stir. It’s a color changing twist on a Tom Collins, and a showy purple drink for a fall party, a Halloween table or a spring brunch.

Why You Will Love This

The glass starts pale and clear. Then the blue butterfly pea syrup goes in, and purple blooms through the drink like watercolor on wet paper. The drink itself tastes bright and citrusy, with juniper from the gin, tart lemon and fizzy soda. The syrup is the only thing not already on your bar cart, and it keeps in the fridge for weeks.

The Story Behind It

Butterfly pea flower (Clitoria ternatea) has long been used in Thai and Malaysian cooking as a natural blue dye for rice and desserts. The flowers contain anthocyanins, the same pigments found in red cabbage, and they change color with acid. Add lemon and the blue shifts toward purple or pink. So the lemon goes in the glass first and the blue syrup last, and guests get to watch the change happen.

Bright blue butterfly pea flower cocktail in coupe glass with gin bottle and dried butterfly pea flowers scattered on white marble, natural light casting shadows
Before it meets the lemon, the butterfly pea syrup is a deep, glowing blue.

What You Will Need

For the butterfly pea syrup:

  • 1/4 cup dried butterfly pea flowers
  • 1 1/2 cups water
  • 3/4 cup granulated sugar

For the cocktail:

  • 2 ounces gin (or vodka)
  • 1 ounce freshly squeezed lemon juice
  • 4 ounces club soda
  • 3/4 ounce butterfly pea flower syrup
  • Ice
  • 1 slice lemon, for garnish
  • 1 sprig fresh mint, for garnish

How to Make It

  1. Make the butterfly pea syrup. Add the dried flowers and water to a saucepan over medium-high heat. Bring to a boil, then reduce to a simmer for 15 minutes. Take it off the heat.

  2. Strain and sweeten. Pour the hot liquid through a fine-mesh sieve to remove the flowers. Measure what is left, return it to the pot over medium heat and stir in the same amount of sugar until it fully dissolves. Let it cool completely, then pour it into a clean jar and refrigerate. It keeps in the refrigerator for up to a month.

  3. Shake the base. Fill a cocktail shaker with ice. Add the gin and lemon juice and shake well.

  4. Pour and top. Strain into a highball glass filled with ice and top with the club soda.

  5. Add the color. Serve the butterfly pea syrup on the side. Pour 3/4 ounce into the drink right before sipping, stir gently and watch the color change.

  6. Garnish. Finish with a lemon slice and a sprig of mint.

Pouring blue butterfly pea syrup into a gin and lemon cocktail, purple color beginning to swirl through the drink, condensation on glass
The moment the blue syrup meets the lemon, purple begins to bloom through the drink.

Tips for the Best Color

Add the syrup last. The color change is the show, so keep the syrup on the side and pour it in front of guests.

Use fresh lemon. Fresh juice gives the brightest flavor and the clearest shift from blue to purple.

Pick a clean gin. A London dry gin with plenty of juniper and citrus peel suits the lemon. Very floral gins can compete with the citrus. Vodka works too if you want a neutral base.

Store the syrup in a clean jar. Keep it in the refrigerator and use it in lemonades, iced tea or any drink that could use a splash of blue.

Make It Your Own

For a garden party or fall gathering, set out a tray of glasses with the gin, lemon and soda ready, and a small pitcher of butterfly pea syrup so each guest can pour their own and watch their glass turn purple.

If you want a mocktail version, leave out the gin and use lemon juice, club soda and the butterfly pea syrup over ice. The color change works the same way, since it comes from the lemon and the flowers, not the alcohol.

For a different spirit, swap the gin for vodka. Clear spirits show the color shift best, so skip dark spirits like whiskey or aged rum.

Finished purple butterfly pea flower cocktail with gin and lemon in rocks glass with ice, garnished with lemon wheel and purple pansy, outdoor garden setting with soft natural light
The finished drink settles into a gradient of purple and blue.

Common Questions

What does butterfly pea flower taste like in cocktails?

Very little. The dried flowers taste faintly earthy and grassy, a bit like green tea , and you can barely notice it once they’re mixed with gin, lemon and sugar. The flowers are there for the color.

How do you make a color changing cocktail with butterfly pea flower?

Make a blue syrup from the dried flowers, then pour it into a drink that contains lemon juice. The acid shifts the color from blue to purple. Add the syrup last so the change happens in the glass. The same trick works in lemonades and iced teas .

What spirits pair best with butterfly pea flower?

Clear spirits show the color most clearly. Gin is the classic choice because its juniper and citrus work with the lemon, and vodka is a good neutral swap. Dark spirits hide the blue and purple.

Can you make butterfly pea cocktails without alcohol?

Yes. Skip the gin and build the drink with lemon juice, club soda, ice and the butterfly pea syrup.

How long does the butterfly pea syrup keep?

Stored in a clean jar in the refrigerator, it keeps for up to a month. Make it ahead and the cocktail takes about two minutes.