2024 Ultimate Guide to Match Hydrangea and Soil pH

type

status

date

slug

summary

1. All About Hydrangeas

The word "hydrangea" comes from Greek, where "hydro" means water and "angeion" means container. Hydrangea is a shrub. Some of the most common types of hydrangeas include mopheads, lacecaps, Endless Summer, etc. During the blooming period, these hydrangeas will bloom eye-catching flowers.

2. The Importance of Soil pH

My hydrangeas need the right kind of soil to stay healthy. They like soil with lots of organic matter and a pH of 4.5-7.0. Of course, well-drainage is also essential. Poor drainage will make the root rot, so I must ensure the soil does not waterlog.

To make sure the soil quality is good, I add compost and manure to the soil. Some organic matter in the soil is great for keeping it in good structure and holding onto water and nutrients. I think mixing peat moss and perlite is a good choice.

3. The pH of Soil

The pH scale measures whether the soil is more acidic or alkaline, ranging from 0 to 14. A pH of 7 is neutral. If the pH is below 7, the soil is acidic. If the pH is above 7, the soil is alkaline.

Most of the soil in Japan is weakly acidic or acidic, while the soil in Europe is weakly alkaline. The soil pH in the USA is between 6.0 and 7.5.

Most hydrangeas grow in acidic soil and have blue flowers; if they grow in alkaline soil, they have red or pink flowers.

Anthocyanins in hydrangea cells are red, and when anthocyanins combine with aluminum in the soil, red becomes blue. Aluminum ions in acidic soils are readily soluble in water, so plants can easily absorb them. Hydrangea blooms turn blue when aluminum ions in the soil mix with anthocyanins.

Hydrangeas (Endless Summer) turn blue in acidic soils.

On the contrary, aluminum ions in alkaline soils are not readily soluble in water, and plants cannot absorb them. Therefore, hydrangea flowers will show the original color of anthocyanins; that is, hydrangea flower colors are pink or red.

4. Testing Soil pH

I will conduct a soil test before adjusting the soil pH levels. If you want to grow hydrangea in your backyard or pot, I suggest you try the following four steps.

The right time

Preparing the soil

pH test tools

Check the result

4.1 The Right Time

Before I start testing, I will ensure I have the necessary tools and give myself enough time to get accurate results.

Generally, I test the soil’s pH level in spring or fall when the soil is neither too dry nor too wet. At the same time, I will stop using anything that can change the soil pH 15 days before the test. In this way, I can make sure that the results are accurate.

4.2 pH Test Tools

Testing tools can easily measure soil pH in the garden or pots. Two common testing tools are test strips and long probe pH testers.

Using test strips is very easy. First, I put the soil into the water and stirred, then rested the solution and waited for it to stratify. Then, I dip the test strip in the top solution for 3-5 seconds. Finally, I compare the changed color with the color table to get the pH of the soil.

I prefer to use the pH test strips for soil pH testing. The test results shown by the pH test strip are more accurate.

Although pH test strips are a traditional testing tool, their accuracy is very high.

Long probe pH tester relies on good contact between the probe and soil. When growing hydrangeas, I use peat moss, which makes it impossible for the probe to have complete contact with the soil. So, the long probe pH tester is not a better option for precise testing.

5. Changing Soil pH

5.1 Garden

I will adjust the soil pH in my garden based on the soil pH test results.

I will use soil acidifiers or 21-7-7 fertilizer if I want blue hydrangeas. If I wish red or pink hydrangeas, I will scatter lime into the soil when it grows new buds or before blossoms.

I avoid rainy days when doing this work since the heavy rain will wash away the fertilizer. In this way, it will fail to achieve the desired results and pollute the environment.

5.2 Container or Pots

In contrast, there is not much soil in the pots, and I can control the amount of watering. Hence, the soil pH in the pots is easy to adjust. There are two ways to adjust the pH in pots: change the soil or not.

Change the soil: bloom blue flowers.

If I want blue hydrangeas, I will mix four portions of small Akadama, four portions of peat moss, and two portions of vermiculite to make acidic soil.

I will use fertilizers rich in potassium but low in phosphonic acid to keep the lasting blue. So, I will avoid using bone meals because of their high phosphoric acid content.

The mixture of Akadama, peat moss, and vermiculite is the acidic soil needed for hydrangea.

Change the soil: bloom pink or red flowers.

If I want hydrangea to bloom pink or red, I will mix four portions of small Akadama, four portions of compost, and two portions of vermiculite to make weakly alkaline soil.

To make pink eternal, I will use fertilizers rich in nitrogen and phosphorus, such as bone meal and fish meal. But I will try not to use potassium-rich fertilizers.

The mixture of Akadama, compost, and vermiculite is the alkaline soil needed for hydrangea.

Do not change soil:

If I do not change the soil, I can also use potions or lime to adjust the pH of the soil. But I will be cautious because overuse will cause damage to the roots of plants.

I will apply 500 to 1000 times the aluminum sulfate solution to the soil one month before the hydrangea blossoms. Use 2-3 times every 20 days so my hydrangea can bloom blue flowers.

If I scatter lime into the soil of the hydrangea a month before it blossoms, my hydrangea will bloom pink or red flowers.

You will like Endless Summer, Incrediball, Korinji Temple, and Peppermint if you like the blue-bloom color as much as I do. Their blue flowers will make your backyard the focus of the community.

6. Special Varieties

Not all hydrangeas can change the color of flowers with a change in soil pH. Hydrangeas with pure white or bright red flowers will not turn blue even if planted in acidic soil. However, near withering, the white or cream hydrangea flowers will appear a light blue in the acid soil. In contrast, they will have a hint of red in the alkaline soil.

Some hydrangeas begin flowering in white-green colors, then gradually turn into their unique color. When they start wilting, they turn green and eventually become red or purple. This color turn has nothing to do with the soil pH.

Hydrangea serrata 'Kurenai' flowers are bright red in the intense sun. Still, its flowers turn white in the shade. When I saw it first in Japan, I thought it was two different varieties. Strangely, the soil's pH does not change these flowers' color.

7. Conclusion

The first time I planted a hydrangea, I got hooked on how the hydrangea flower color changed. From blooming to withering, hydrangea will change flower color, which becomes a great pleasure to watch hydrangea. I couldn't stop myself from admiring it. I hope my insights into soil pH and color changes will help you. Have a nice gardening trip.

Bibliography:
Hydrangea blooms turn colors based on soil pH levels.
The chemical mechanism for Al3+ complexing with delphinidin: A model for the bluing of hydrangea sepals, Henry D. Schreiber, Amy M. Swink, Taylor D. Godsey, Journal of Inorganic Biochemistry, Volume 104, Issue 7, 2010, Pages 732-739, ISSN 0162-0134, https://doi.org/10.1016/j.jinorgbio.2010.03.006.
The Role of Soil pH in Plant Nutrition and Soil Remediation, Dora Neina, Applied and Environmental Soil Science, vol. 2019, Article ID 5794869, 9 pages, 2019. https://doi.org/10.1155/2019/5794869
Blueing of sepal colour of Hydrangea macrophylla, Kǒsaku Takeda, Miyuki Kariuda, Hideaki Itoi, Phytochemistry, Volume 24, Issue 10, 1985, Pages 2251-2254, ISSN 0031-9422, https://doi.org/10.1016/S0031-9422(00)83019-8.

My name is Arthur Mo. I am a gardener who loves gardening so much. I graduated from Ocean University of China. After I returned to Japan, I began to learn how to cultivate hydrangeas and daisies. Mr. Mitsuhiro (my master) taught me to sow, cut, fertilize, and manage diseases and pests. For nine years, I have been sharpening my planting skills. In 2022, my family and I moved to Florida. The warm climate of Florida gives me the impulse to continue cultivating hydrangeas and daisies. I began my gardening trip in my backyard and unswervingly contributed my efforts to these plants. I love these plants deeply, and at the same time, I also thank my family, my master, and friends for their understanding and support.