Can Pennies Turn Hydrangeas Blue? Gardening Myths Debunked
Use soil acidity and aluminum availability to create vibrant blue blooms without myths.
Myth or Fact: Do Pennies Change the Color of Hydrangeas?
Gardeners everywhere are captivated by the striking color changes possible in hydrangea blooms. Among advice shared in gardening circles, one popular tip claims you can turn hydrangeas blue simply by burying pennies in your soil. But does this claim have any scientific merit? Letâs cut through the myth and look at the facts.
The Short Answer
No, pennies will not turn hydrangeas blue. The vibrant blue color in hydrangea flowers is due to acidic soil conditions and the presence of aluminum, not because of copper or any other metal found in pennies. Even if you bury a stash of coins, their effect on soil pH and bloom color is negligible. Instead, your spare change is better invested in your garden elsewhere.
The Science Behind Hydrangea Color
Hydrangea color is primarily determined by two factors:
- Soil pH: Acidic soil (pH below 6.5) leads to blue blooms, while alkaline soil (pH above 7) typically results in pink flowers.
- Aluminum availability: Blue flowers appear when hydrangea roots absorb aluminum, which is more accessible in acidic conditions.
Simply put, if your soil lacks acidity or available aluminum, your hydrangea will remain pinkâeven if you dole out your copper collection.
The Penny Myth: Origins and Reality
The belief that pennies can alter hydrangea colors likely arises from their historical composition. Before 1982, pennies contained mainly copper, which some assumed would influence soil pH. However, modern pennies are primarily zinc with a copper coating, and even old pennies contain nowhere near enough copper to change your garden’s chemistry. Furthermore, copper is not an acidifying agent for soil nor does it provide the required aluminum for blue flowers.
Hereâs why the penny myth falls short:
- Even with thousands of pennies, the copper content is far too low to change pH or provide essential nutrients.
- No scientific studies show a correlation between penny burial and flower color.
- Soil acidity and aluminum, not copper, are the determining factors in hydrangea color.
How Can You Really Turn Hydrangeas Blue?
If your gardening goals include luscious blue hydrangeas, focus on your soil. Here are proven methods to achieve the desired shade:
- Test your soil pH: Use a soil test kit to measure acidity near your hydrangeas.
- Lower the pH: Add amendments like sulfur or peat moss to acidify alkaline soils.
- Supply aluminum: In acidic soil, add aluminum sulfate to make aluminum available for the plants.
- Choose the right variety: Not all hydrangea types change colors; pick those with changeable blooms, such as Hydrangea macrophylla (mophead or lacecap varieties).
| Method | Effect | How to Apply |
|---|---|---|
| Apply Aluminum Sulfate | Turns blooms blue | Mix into soil in spring; follow package directions |
| Add Garden Lime | Turns blooms pink | Scatter on soil in fall or winter; raises pH |
| Incorporate Sulfur | Lowers pH, promotes blue color | Work into soil before planting or around roots |
| Choose Blue Varieties | Reliable blue blooms | Plant cultivars genetically predisposed to be blue |
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Understanding Penny Composition and Its Effect
Letâs dig a bit deeper into the pennyâs makeup. Pennies minted before 1982 were about 95% copper and 5% zinc. Those minted after 1982 are 97.5% zinc and just 2.5% copperâhardly enough to make a difference in a garden bed, especially considering copper isnât a soil acidifier nor linked to flower coloring.
Hereâs what you should know about using metals in your garden:
- Copper is mostly inert and not easily released into soil from pennies.
- Zinc, besides being unnecessary for hydrangea color, can be toxic in high concentrations.
- There is no scientific or anecdotal evidence that penny burial affects hydrangea hue.
- Pennies may corrode in wet, acidic soilâbut this only releases minute metallic ions, not the aluminum needed for blue blooms.
Why Pennies Canât Acidify Your Soil
Acidifying soil involves increasing hydrogen ion concentration, typically through sulfur amendments, peat moss, or pine needles. Pennies, being mostly copper or zinc, simply do not react with the soil in a way that meaningfully changes acidity. Even large quantities would only make marginal changes, insufficient for hydrangea color transformation. Root and bloom health relies on correct pH management, not metallic additives like coins.
Common Questions About Hydrangea Color
Can every hydrangea variety change color?
No. Only Hydrangea macrophylla varieties, including mopheads and lacecaps, are responsive to pH and aluminum. White hydrangeas, for example, will generally remain white regardless of soil adjustments.
Is there any benefit to burying pennies near plants?
There is no documented benefit to hydrangea color or overall plant health from burying pennies. Occasionally, copper compounds are used to treat fungal diseases elsewhere in gardening, but not for hydrangea color shifting.
How long does it take for soil amendments to change bloom color?
Color change isnât instant. Expect gradual transformation over several months, sometimes taking until the following flowering season for full-color development. Regular soil testing and proper amendment quantities are important for success.
Blue Hydrangea Varieties to Try
If your aim is reliable blue blooms without fuss, consider planting cultivars that naturally display rich blues and require little intervention. Below are three popular varieties:
- Nantucket Blue: A mophead hydrangea renowned for seaside-inspired blue flowers. It blooms on both old and new wood, ensuring continuous color. Hardy in zones 5â9.
- Nikko Blue: This classic shrub provides abundant blue flowers through early summer and grows to about six feet tall. It blooms on older wood, so prune after flowering if necessary.
- Penny Mac: An easy-maintenance mophead variety covered in giant blue blooms all summer. Grows quickly and thrives with little pruning, making it popular among gardeners seeking low-effort color.
Alternatives to the Penny Trick
- Focus on proven soil amendments such as sulfur, aluminum sulfate, or garden lime depending on the desired flower color.
- Use mulch from pine needles for ongoing acidity adjustment.
- Pick hydrangea varieties known for their natural blue hues to avoid labor-intensive soil modification.
- Regularly test your soil and keep it within optimal ranges for the kind of hydrangea youâre cultivating.
Gardening Wisdom: Fact vs. Folklore
Itâs easy for good-intentioned myths to spread, especially when gardening success depends on subtle factors like soil chemistry. However, scientific understanding enables gardeners to make informed choices. Burying pennies can be considered a harmless traditionâbut for blue hydrangeas, itâs soil pH and aluminum that matter.
- Always seek reliable sources for plant care advice.
- Use empirical testing (like soil pH kits) rather than folklore when problems arise.
- Put spare change towards actual amendments or garden additions rather than burying it in hope.
Frequently Asked Questions (FAQs)
Will copper from pennies harm my plants?
No, copper from pennies is largely inert and not released in quantities that would harm hydrangeas or other garden plants. There is no evidence of toxicity for common garden scenarios.
How often should I amend my soil to maintain blue hydrangeas?
Monitor soil pH annually. Amend with aluminum sulfate or sulfur in spring for optimal blue coloration, but avoid over-applying as excessive acidity can stress your plants.
Are there other garden myths similar to the penny trick?
Yes, many garden myths circulate, such as using Epsom salt for everything or coffee grounds for acidifying soil. Verify each tip with research or professional advice before applying in your garden.
Where can I find the best hydrangea varieties for blue blooms?
Look for mophead and lacecap types at reputable garden centers, and ask about cultivars like ‘Nantucket Blue’, ‘Nikko Blue’, and ‘Penny Mac’ for reliable results.
Conclusion: Save Your Pennies!
Itâs clear: pennies will not turn your hydrangeas blue. Effective color control comes down to managing your soil’s acidity and providing the necessary aluminum. Rather than relying on folklore, invest in scientifically proven garden amendments and proper hydrangea care. With accurate information, you can achieve the vivid blue blooms that add beauty and charm to gardens everywhere.
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