Quck answer
To make hydrangeas red, you can adjust the soil pH level. Acidic soil with a pH below 6.0 promotes red coloration in hydrangeas. You can achieve this by adding amendments like aluminum sulfate or elemental sulfur to the soil. These amendments lower the soil pH and encourage red pigmentation. Additionally, providing adequate sunlight and water to your hydrangeas will help enhance their color. Remember to monitor the soil pH regularly and adjust as needed to maintain the desired red hue.
Typically, when someone thinks of a bigleaf hydrangea (Hydrangea macrophylla), they imagine shades of baby blue or pink. However, with the right cultivar selection and soil modifications, you can achieve beautiful shades of red.
The Allure of a Hydrangea
A bigleaf hydrangea is a low-maintenance perennial shrub with stunning, large blossoms that adorn a garden throughout the summer season. Two types of blossoms are produced by this plant: mopheads, which are pompom in shape, and lacecaps, which are disk-shaped. The plant’s ability to change color is its claim to fame. In acidic soil, the flowers are blue, while alkaline soil produces pink flowers.
Increasing Pink
If you desire pale red hydrangea flowers, you can increase the alkalinity of the soil to deepen the pink color. Soil acidity is measured on a pH scale from 0 to 14. A neutral pH is 7, and anything below 7 is acidic. The higher the pH, the more alkaline the soil, resulting in rosier flowers. Eventually, the flowers may turn red.
Deeper Reds
If you’re seeking a deeper red color, consider purchasing a red hydrangea cultivar, such as “Ami Pasquier” (Hydrangea macrophylla “Ami Pasquier”). This type of bigleaf hydrangea flourishes in USDA plant hardiness zones 6 through 9 and produces round, compact “mophead” shrubs that can grow up to 4 feet tall. In acidic soil, the flowers are blue, but in alkaline soil, they transform into a deep crimson red.
Using Lime
If you need to increase the alkalinity of your soil further to achieve your desired red shade, adding lime can help. Dolomitic or agricultural lime can be added to increase alkalinity. Sprinkle 1 cup of lime around the dripline of each shrub in the spring and fall, watering it in well. Repeat until the flowers achieve your desired shade. For faster results, dissolve 1 tablespoon of hydrated lime into 1 gallon of water and water the soil around the plant generously in March, April, and May, being careful not to drip any on the foliage.
FAQ
1. Can I change the color of my hydrangeas to red?
Yes, you can change the color of your hydrangeas to red. The color of hydrangea flowers is determined by the pH level of the soil. To make your hydrangeas red, you need to lower the pH level of the soil to make it more acidic. You can do this by adding aluminum sulfate or sulfur to the soil. These products help to acidify the soil and promote the growth of red pigment in the flowers. Remember to follow the instructions on the package and test the soil pH regularly to ensure it remains within the desired range.
2. How often should I apply aluminum sulfate or sulfur to my hydrangeas?
You should apply aluminum sulfate or sulfur to your hydrangeas once or twice a year. It is recommended to apply these products in early spring and again in late summer or early fall. This timing allows the hydrangeas to absorb the necessary nutrients and promote the growth of red pigment in the flowers. Be sure to follow the instructions on the package for the correct application rate and method, as excessive use can harm the plants.
3. Are there any alternative methods to make my hydrangeas red?
Yes, there are alternative methods to make your hydrangeas red. One method is to use a specific fertilizer designed for producing red flowers. These fertilizers typically contain high levels of phosphorus, which can enhance the red coloration of hydrangea flowers. Another method is to mulch around the base of the plants with pine needles or coffee grounds. These organic materials can help to acidify the soil and promote the growth of red pigment. Remember to monitor the pH level of the soil regularly to ensure it remains suitable for red hydrangeas.
4. Can I change the color of my hydrangeas from blue to red?
Yes, you can change the color of your hydrangeas from blue to red. Blue hydrangeas thrive in acidic soil with a pH level between 5.0 and 5.5, while red hydrangeas prefer even more acidic soil with a pH level between 4.5 and 5.0. To transition your blue hydrangeas to red, you need to lower the pH level of the soil by applying aluminum sulfate or sulfur. However, it’s important to note that the transition may take time and multiple applications to achieve the desired color change.
5. Can I make my hydrangeas red if I have alkaline soil?
It can be challenging to make hydrangeas red if you have alkaline soil. Hydrangeas tend to produce blue flowers in alkaline soil and pink or red flowers in acidic soil. However, you can still try to make your hydrangeas red by amending the soil with aluminum sulfate or sulfur to lower the pH level and make it more acidic. It’s important to note that the success of color change may vary depending on the original pH level of the soil and the specific cultivar of hydrangea you have.
6. What other factors can affect the color of hydrangea flowers?
Apart from soil pH, other factors can also affect the color of hydrangea flowers. The availability of aluminum in the soil plays a crucial role in coloration. If the soil lacks aluminum, the flowers may appear pink or white regardless of the pH level. Additionally, the genetics of the hydrangea cultivar can influence the color. Some cultivars are naturally predisposed to produce red flowers, while others are more likely to produce blue or pink flowers. Understanding these factors can help you choose the right hydrangea cultivar and create the desired flower color.
7. Can I revert my hydrangeas back to their original color after making them red?
Yes, you can revert your hydrangeas back to their original color after making them red. If you want to return your hydrangeas to their original blue or pink color, you can adjust the pH level of the soil accordingly. For blue flowers, you need to raise the pH level by applying garden lime. For pink flowers, you need to slightly raise the pH level by adding dolomitic lime. Remember to monitor the pH level of the soil regularly and make gradual adjustments to avoid shocking the plants. It may take some time for the colors to transition back to their original shades.