Pickle juice, also known as brine, is the liquid leftover from pickling vegetables like cucumbers. Some gardeners use pickle juice as a home remedy for helping hydrangeas change color. The acids in the pickle juice are thought to affect the soil pH around hydrangeas, impacting how the flowers absorb anthocyanins and turning the blooms different colors. But what does science actually say about using pickle juice for hydrangeas?
The Short Answer
Applying diluted pickle juice to hydrangea soil can help produce blue flowers on some types of hydrangeas by lowering the pH. It provides acids that cause the flowers to uptake more aluminum and turn blue. But it does not work for all types of hydrangeas.
How Hydrangeas Change Color
Hydrangeas are unique flowers because they can produce blooms in different colors depending on the soil they are grown in. The most common hydrangea colors are pink, blue, and purple. Whether hydrangeas turn pink or blue depends on the pH of the soil and the availability of aluminum:
- Pink hydrangeas form in more alkaline soils with a pH above 5.5. At this higher pH, the flowers cannot take up aluminum.
- Blue hydrangeas form in more acidic soils with a pH below 5.5. The lower pH makes aluminum available to the plant, which produces blue flowers.
- Purple hydrangeas form in soils with a pH right around 5.5. They uptake some but not too much aluminum, resulting in a mix of pink and blue.
The uptake of aluminum is important because hydrangeas contain a pigment molecule called anthocyanin. The more aluminum a hydrangea takes up, the more this anthocyanin turns blue. With less aluminum, it stays red/pink.
Soil pH Affects Aluminum Uptake
The essential factor that controls the anthocyanin color is the acidity (pH) of the soil. Hydrangeas grown in acidic soils below pH 5.5 are able to absorb more aluminum through their roots. This aluminum moves up into the flowers and turns the anthocyanins blue. In more alkaline soils above pH 5.5, less aluminum is available. So the anthocyanins remain pinkish or reddish in color.
How Pickle Juice Acids Lower pH
This is where pickle juice comes into play. Fresh pickle juice has a very low pH around 2.5-3.5, making it highly acidic. Diluting pickle juice 1:3 or 1:4 with water and pouring it around the roots of hydrangeas can help lower the pH of the soil. The main acids in pickle juice are acetic acid and lactic acid.
As these acids from the pickle brine dissolve into the soil, they effectively lower the pH, making the area more acidic. This, in turn, makes aluminum more available to the hydrangea’s roots. The more aluminum the roots uptake, the bluer the flowers become.
Quick Summary of Using Pickle Juice for Hydrangeas
- Pickle juice contains acids like acetic acid and lactic acid
- These acids can help lower (acidify) the pH of alkaline soils
- Lower soil pH = more available aluminum
- More aluminum uptake by roots = bluer flowers
What Types of Hydrangeas Turn Blue with Pickle Juice?
However, pickle juice only works to turn some varieties of hydrangeas blue. The main types that will turn blue when given more aluminum are:
- Bigleaf hydrangeas (Hydrangea macrophylla) – the most popular garden hydrangeas
- Oakleaf hydrangeas (Hydrangea quercifolia)
- Mountain hydrangeas (Hydrangea serrata) – typically have smaller blooms than bigleaf varieties
On the other hand, other types of hydrangeas will NOT turn blue even if given more aluminum:
- Smooth hydrangeas (Hydrangea arborescens) – commonly grown ‘Annabelle’ hydrangeas
- Panicle hydrangeas (Hydrangea paniculata) – cone shaped blooms like ‘Limelight’
- Climbing hydrangeas (Hydrangea anomala)
So before using pickle juice, make sure you actually have a type of hydrangea that can turn blue!
Should You Use Pickle Juice on Hydrangeas?
Using diluted pickle juice can be an easy home remedy to turn hydrangea blooms blue instead of pink. However, there are a few things to keep in mind:
- Test your soil’s pH first to see if it needs lowering. Use a soil testing kit to check the pH around your hydrangeas. Apply pickle juice if pH is above 5.5.
- Dilute the pickle juice at least 1:3 with water, or even more. Undiluted pickle juice may be too acidic.
- Monitor the results and don’t overdo it. Too much can make soil excessively acidic.
- Rinse pickle juice off foliage to avoid leaf burn.
- Repeat applications may be needed through the season.
- Still may not work as well as aluminum sulfate.
While pickle juice can provide the acids to help lower your soil pH, it is not as precise or effective as using traditional soil amendments. But it can be a handy, natural product to try when your alkaline soil needs more acidity.
Using Aluminum Sulfate on Hydrangeas
If you want guaranteed blue hydrangea blooms, using aluminum sulfate is a more precise and effective method. Aluminum sulfate, also called alum, provides soluble aluminum directly to the plant rather than indirectly changing the soil pH. This means you can see quick, foolproof results.
To use aluminum sulfate, you dissolve pellets or powder in water and drench it around the hydrangea roots. The aluminum is immediately absorbed by the roots and travels to the blooms. Within 1-2 weeks, pink blooms will transform to blue.
Benefits of Using Aluminum Sulfate
- Very effective at turning flowers blue
- See color change in 1-2 weeks
- Lower risk of over-acidifying soil
- Can be used for potted plants
- Simpler pH-independent solution
The downsides are that aluminum sulfate is more expensive than pickle juice and needs to be applied each year. But for most gardeners, it provides reliable, fuss-free blue hydrangea blooms.
What Ratio of Pickle Juice to Water for Hydrangeas?
If you want to experiment with pickle juice to alter hydrangea colors, it’s important to dilute it substantially. Undiluted pickle juice is much too acidic and risks burning the roots. A good recipe is:
- 1 part pickle juice
- 3-4 parts water
So for example, mix 1 cup pickle juice with 3-4 cups water. Water down the pickle brine as much as possible while still releasing some acidity into the soil. Test with pH strips to identify the ideal dilution ratio for your soil.
How to Apply Diluted Pickle Juice to Hydrangeas
Here is a simple process for using diluted pickle juice on hydrangeas:
- Use a soil pH tester to check the current pH around your hydrangeas. Look for pH levels above 5.5.
- Dilute fresh pickle juice at a 1:3 or 1:4 ratio with water. Mix thoroughly.
- Pour the diluted pickle juice slowly around the roots and soil of the hydrangeas.
- Monitor the color change of blooms over the next 1-2 months.
- Reapply more diluted pickle juice as needed through the season.
Avoid getting pickle juice on the leaves and flowers themselves, as the acids and salts may burn. Focus applications around the root area. You may need reapply every 1-3 months depending on rainfall and your soil type.
When to Apply Pickle Juice to Change Hydrangea Color
The best times of year to use pickle juice or other soil acidifiers for blue hydrangeas are:
- Spring – 4-6 weeks before blooms open for the season
- Fall – 6-8 weeks before plants go dormant
This gives the acids time to thoroughly soak into the soil and alter the pH before the hydrangea needs to uptake aluminum for next year’s flowers. For potted hydrangeas, you can apply pickle juice throughout the active growing season as needed.
Does Pickle Juice Work Instantly on Hydrangeas?
No, pickle juice does not instantly change hydrangea bloom color. It can take 1-2 months for the acids to thoroughly permeate the soil and make aluminum available to the plant roots. The lowest soil pH levels are reached about 4 weeks after applying diluted pickle brine. So have patience!
For the fastest color change, use aluminum sulfate instead. It provides immediate soluble aluminum to the roots and you’ll see results in just 1-2 weeks. But if you don’t mind waiting, pickle juice can be an inexpensive alternative.
Conclusion
While not a perfect solution, pickle juice can be a handy way to acidify soil and alter hydrangea colors. Diluting it substantially before pouring around the root zone is crucial. Monitor your soil pH and bloom colors closely when trying this home remedy. And know it does not work for all hydrangea varieties. But as an easy, natural product found in most homes, pickle juice is worth experimenting with to turn those pretty blooms blue!
