Change the Color of Bigleaf Hydrangeas
Want blue or purple blooms instead of pink? You can change the color of Bigleaf Hydrangeas with a few simple soil tweaks. All it takes is understanding your soil pH, choosing the right Hydrangea macrophylla variety, and following a steady care schedule.
Whether you're going for bold blue or passionate pink, here’s how to control your Hydrangea color game like a pro!
- Which Hydrangeas Can Change Flower Color?
- Blue Hydrangea Color Change Cheat Sheet: Step-by-Step
- How To Keep Hydrangea Flowers Pink or Red
- Plum in the Middle: Growing Gorgeous Lavender and Purple Hydrangeas
- General Hydrangea Care For Colorful Success
Hydrangeas Have Come a Long Way—So Have Their Colors
There are many kinds of Hydrangeas available today. Maybe plant breeders got a little color-happy in recent years, but we’re not complaining! Thanks to a breakthrough in cold-climate breeding, these beauties now bloom in more gardens than ever.
Nature Hills offers a curated collection of some of the newest and best Hydrangea varieties on the market—think more flower power, compact habits, and dreamy new shades of pinks, reds, purples, and blues!
Which Hydrangeas Can Change Flower Color?
Not all Hydrangeas can color-shift. Only Bigleaf Hydrangeas (Hydrangea macrophylla)—including both Mophead and Lacecap types—respond to changes in soil pH.
- Mophead varieties have bold, rounded clusters of flowers.
- Lacecap types display delicate, flat-topped blooms with a ring of open flowers surrounding tiny fertile florets.
When grown in lower pH (acidic) soil, Bigleaf Hydrangeas produce lavender, purple, or blue flowers. In higher pH (alkaline) soils, they bloom in pink or red tones.
Other Hydrangea Types Don’t Respond to Soil pH:
- Hydrangea arborescens (like the classic Annabelle)
- Hydrangea paniculata (like Limelight or Pinky Winky)
- Hydrangea quercifolia (Oakleaf Hydrangea)
These types will not change flower color based on pH, though their blooms may naturally age to soft pink or antique tones over time.
Blue Hydrangea Color Change Cheat Sheet: Step-by-Step
If your Bigleaf Hydrangea is blooming pink but you want moody blues, here’s how to change things up and keep them that way:
Step-by-Step Schedule for Turning Hydrangeas Blue:
- Test Your Soil First
- Use a pH test kit or contact your local County Extension Office to test your soil’s pH and fertility.
- For blue or purple blooms, aim for pH 5.0 to 5.5.
- Choose the Right Amendment
- Use Aluminum Sulfate or Elemental Soil Sulfur to lower pH.
- Aluminum sulfate also provides the key element—aluminum—that makes blue flowers possible.
- Apply Aluminum Sulfate Solution
- Mix 1 tablespoon aluminum sulfate per 1 gallon of water.
- Water your Hydrangeas with this solution every 2–3 weeks throughout the growing season.
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Important: Always water the soil well before applying the solution to avoid burning roots.
- Mulch With Acidic Materials
- Add pine bark, pine needles, or peat moss as mulch.
- These materials help maintain low pH naturally while enriching your soil.
- Use a Fertilizer for Acid-Loving Plants
- Apply a fertilizer that’s low in phosphorus and high in potassium (like 25-5-30).
- Avoid high-phosphorus fertilizers (like 10-30-10) as phosphorus ties up aluminum in the soil.
- Repeat Annually
- Continue treatment each year as soil pH naturally shifts back over time.
- Keep testing soil pH and adjust applications as needed.
How To Keep Hydrangea Flowers Pink or Red
Prefer pretty in pink? You’ll want to raise your soil pH slightly and avoid aluminum uptake:
- Apply garden lime (Dolomitic Lime) to the soil.
- Aim for a pH between 6.0 and 6.5.
- Avoid using aluminum sulfate or sulfur.
- Use fertilizers high in phosphorus (like 15-30-15) to block aluminum absorption.
Plum in the Middle: Growing Gorgeous Lavender and Purple Hydrangeas
If you're swooning over the dreamy lavender or soft violet blooms that straddle the line between pink and blue, you're in luck—you can absolutely grow Hydrangeas in this sweet spot. The trick? Keep your soil pH neutral to slightly acidic, where both pink and blue pigments blend together beautifully.
Target pH for Purple Hydrangeas:
- Aim for a pH between 5.5 and 6.0
- This range allows the plant to absorb just enough aluminum for a mix of red and blue pigments to show up in the blooms
Tips to Keep Your Hydrangeas Lavender or Purple:
- Test and Monitor Regularly
- Use a soil pH test kit every few weeks during the growing season
- Adjust slowly—drastic changes in pH can swing the color too far in one direction
- Apply Small Amounts of Aluminum Sulfate
- Mix ½ tablespoon aluminum sulfate with 1 gallon of water
- Apply monthly for a gentle shift without overpowering the pink tones
- Use Acidifying Mulch
- Pine needle or peat moss mulch helps nudge your pH just enough while keeping the soil healthy
- Avoid Excess Lime or Phosphorus
- These will push your blooms toward pink or red and can prevent aluminum uptake
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Choose A Purple Variety
Some Hydrangea macrophylla cultivars naturally lean more purple in the right conditions (like 'Twist-n-Shout®', Let's Dance Lovable®, Froggie™, and Cityline® Rio))
General Hydrangea Care For Colorful Success
No matter what shade you're going for, keep these basics in mind for healthy, happy blooms:
- Slightly acidic, well-drained soil
- High organic matter content
- Mulch over the root zone to maintain moisture
- Protection from harsh afternoon sun
- Consistent watering during dry spells
Learn how to plant your Hydrangea bushes in our Garden Blog Here!
Let Soil pH Paint Your Hydrangea’s
Changing your Hydrangea macrophylla flower color is like garden alchemy—you’re playing with the pH to create your perfect bloom hue. With a little effort and a simple treatment schedule, your shrubs can switch from pretty pinks to bold blues, or stay right in that luscious lavender lane.
And remember—this magic only works on Bigleaf Hydrangeas, so choose your plants wisely. Whether you're aiming for a classic cottage garden feel or modern curb appeal, your Hydrangeas are ready to make a colorful splash. Just grab your soil tester and start changing the landscape—literally!
Happy Planting!
