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Some flowers have the ability to change color based on the pH level of the soil they’re growing in. This natural phenomenon is a subtle signal from your garden about the soil’s chemical composition. In many cases, these changes are triggered by shifts in acidity or alkalinity, especially in flowers that are sensitive to the presence of aluminum or other minerals made available (or locked away) at certain pH levels.
While some flowers may shift hues due to age or weather conditions, others undergo a more dramatic transformation directly tied to the soil’s pH balance. Below are a few stunning flowers known for their pH-dependent color shifts.
Butterfly Pea (Clitoria ternatea)
The butterfly pea is a pea-shaped flower with petals resembling a butterfly’s wing. Its flowers are often deep blue with a yellow center. Butterfly pea can turn red due to the reaction of pigments with the soil pH. In high acidity, they produce purple or pink blooms, and in high alkalinity, they yield blue blooms.
Hydrangea (Hydrangea macrophylla)
Hydrangeas are vibrant and artsy shrubs. Their blooms can either have a lacy or a round shape. Common colors of flowers are purple, blue, white, or pink.
Hydrangeas change colors due to the pH level of the soil. Hydrangeas grown in acidic soil (with a pH below 6.0) have a purple or pink tint on their flowers. Neutral or alkaline (pH above 6.0) soil causes the flowers to have pink or red petals.
Hibiscus (Hibiscus rosa-sinensis)
Hibiscus has trumpet-shaped flowers that can be frilled. Common colors include yellow, purple, red, and blue. Hibiscus can change color because of anthocyanin. Anthocyanin is a pigment that produces red blooms in acidic soils and blue flowers in neutral/alkaline environments. This allows for the soil pH to influence color changes.
Hibiscus can also change colors due to the production of carotenoids. During the hot weather, when carotenoid production is higher, hibiscus will produce bright red and orange blooms. When it reduces during cool weather, the color or the bloom lightens.
Morning Glory (Ipomoea purpurea)
Morning glory has pink, blue, red, white, or purple flowers that resemble a trumpet. The flowers open in the morning and close at night or on cloudy days.
The pH in the petals’ cells increases as the morning glory opens, causing it to turn blue from red. Environmental factors such as humidity and temperature can also cause sudden changes in flower colors.
Tulips (Tulipa)
Tulips are showy and vibrant, featuring blooms in red, yellow, pink, orange, and white. Some tulip varieties (like Apricot Foxx Triumph) are predisposed to color changes. However, environmental factors such as temperature, soil pH, sunlight, etc, can also cause Tulip flower colors to change.
Roses (Rosa rubiginosa)
Roses have layered petals that are often available in various colors, including pink, white, and yellow. In warmer temperatures, flowers can appear light pink. While in cooler weather, they can look deep pink or red.
Rose can also change color due to its soil pH. Acidic soil produces vibrant red flowers, while alkaline soil produces softer red or blue blooms.
African Violets (Saintpaulia ionantha)
African violets are low-growing flowers with five violet-like petals. The flowers are often white, pink, and violet. The hybrid kind has petals that can be spotted around the edges. African violets can change color due to the soil’s pH levels.
However, the main reason why African violets change color is that they’re a hybrid plant with the DNA of more than one parent. The flower can change color to match the parent of its choice.
Four o’clock (Mirabilis jalapa)
This trumpet-shaped bloom opens in the late afternoon or early evening. They have vibrant flowers in yellow, pink, white, and red.
Changing colors can be because of acidic soil which can cause the production of blue anthocyanins, while alkaline soil can make red anthocyanins.
Larkspur (Delphinium)
Larkspurs have tall and elegant spikes of blooms. They can bloom in pink, blue, or purple, and the colors can change for several reasons.
The biggest of them all is the pH. If the pH of the flower’s epidermal cells increases, the flower changes from a reddish purple to a blue with purple hues. Aging can also be another cause of color change.
