It’s the season for hydrangeas or what I like to call, “the mood rings of plants,” because hydrangeas can change colors depending on soil conditions.
Hydrangeas are popular summer-flowering shrubs that are easy to grow and care for. My favorite are the Bright Blue Hydrangeas, so I am sharing my care tips so that you can have these beautiful flowers in your garden, too!
Why I Love Hydrangeas
These flowers are a must in every garden. They will grow in almost any soil, as well as under challenging conditions.
The best time to plant your hydrangeas is either early fall or in the late spring after the cool weather has passed. Once planted, add a 2 or 3-inch layer of mulch over the root zone. The mulch helps to prevent water loss from the soil and helps to keep away weeds.
Hydrangeas come into flower usually in late spring and can last through late November.
Do all Hydrangeas Change Color?
Only two types of hydrangeas will change color. These are called mophead and lacecap flowers, both part of H. macrophyllas.
White hydrangeas can never change color.
How Do I Get Blue Hydrangeas?
It’s the pH of the soil that determines the plant color, specifically whether the plant is getting aluminum. The more acidic the soil, it will be blue. The more alkaline in the soil, the plant will be pinker. If the soil is neutral, you will get half-and-half.
pH levels and colors:
- pH Level <5.5 = Hydrangeas Bright Blue
- pH Level between 5.5 – 6.5 = Hydrangeas Lavender or Purple
- pH level >6.5 = Hydrangeas Pink
To lower your pH, add garden sulfur or aluminum sulfate to your soil. To raise the pH, use ground lime. If you decide to add the acidic soil to your garden, sprinkle it around the bottom of the plant and water it.
Note: Altering the pH of your soil will only work if you have chalk-free ground.
To test the pH, you can use an at-home plant pH testing kit or do the white vinegar test.
The pH testing kit is available at your local garden center or here on amazon. The white vinegar test involves pouring vinegar over the soil and waiting for a reaction. If the vinegar fizzes and bubbles, this means the soil is more alkaline (leading to pink flowers); if no reaction occurs, this means your soil is either neutral or acidic (leading to blue flowers).
Don’t expect the color change to happen overnight. It usually takes several months or a full season to change.
Hydrangea Care Tips
During blooming season, use rainwater to water your hydrangeas. Tap water will only counteract the acidity levels, leading the flowers to change to pink color slowly.
During the offseason, many people cut off the flower heads and compost them. If you had a blue Hydrangea, it is recommended not to do this as the flowers contain aluminum. Take the dead flower head and place it at the base of the plant.
At the end of the year when it decomposes, those nutrients will go back into the soil and make sure you are prepared for your beautiful bright blue hydrangeas during the next season!
Here are some more resources for Hydrangea care tips: