Macrophylla Hydrangea Care & Troubleshooting for Beginners

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1. Common Problems

Good soil makes the root system of bigleaf hydrangea healthy and robust. The correct pruning time will make it bloom more in the next year. It's better to prevent pests and diseases than to treat them.

1.1 Soil

Good soil is the basis for the cultivation of bigleaf hydrangea. Plants can only thrive with enough water and nutrients in the soil. The soil's pH can change the color of some hydrangeas, but that's the last thing I think about. Whether I like pink or blue, I first consider what soil is more suitable for hydrangea growth.

Well-drained

I am sure of a thing: hydrangea likes well-drained soil. Therefore, loam and peat moss are ideal soil types. These two kinds of soil have good drainage and can avoid root rot in hydrangea. At the same time, these two kinds of soil can retain moisture, especially in hot summer.

Organic matter

If you want to help your hydrangea grow and bloom, try planting it in soil with lots of organic stuff. This soil can give your plant all the nutrients it needs to thrive. I maintain soil fertility by adding compost or manure.

Loose

When soil is too compact, it can slow down the growth of roots and make it hard for plants to get the nutrients and water they need from the soil. I will keep the soil loose before planting bigleaf hydrangea. After planting, I do not press the soil too much.

Acidic soil will make hydrangea bloom blue flowers, and alkaline soil will make hydrangea bloom pink flowers. However, the hydrangea's most suitable soil pH is 5.3-7.5. If the soil is too acidic or alkaline, it leads to yellow leaves and fewer flowers in hydrangeas. So remember to check the pH of the soil regularly.

1.2 Leaves turning brown

Reason

The bigleaf hydrangea leaves turn brown because of lack of water and nutrition, root rot, and sunburn.

The leaves of bigleaf hydrangea are large, so the evaporation of water in leaves is also fast. Hydrangea leaves may turn yellow and crisp during hot summers because of lack of water.

On the contrary, overwatering can cause waterlogging in the soil, making the leaves turn brown and leading to root rot. Plants can not absorb water and nutrients from soil because of root rot. The leaves that lack water and nutrients will turn brown or even wither.

It is easy to burn the bigleaf hydrangea in the noon sun because of the large size of its leaves. It's important to note that if a hydrangea growing in the shade is suddenly exposed to direct sunlight, its leaves will turn yellow.

Direct sunlight at noon will burn the leaves of the bigleaf hydrangea.

Hydrangea lacks nitrogen, which can also cause leaves to turn yellow. In case of severe nitrogen deficiency, plant growth will halt.

Solution

I must ensure moist soil, especially in hot summer and dry seasons. I use deep watering when the soil is slightly dry to avoid underwatering and overwatering.

I will add organic matter to improve the caked soil. I will mix the organic matter evenly in the soil instead of gathering it in the plant's roots. If there is too much organic matter around the root, it will injure the roots.

To help hydrangeas thrive, providing partial shade during the hottest times is crucial. When you newly plant a hydrangea, it's better to put it in a spot where it gets some shade. That way, it can adapt slowly to more sunshine.

When there is a lack of nutrients in the soil, I use 10-10-10 slow-release fertilizers. Before blooming, I will spray 0.2% potassium dihydrogen phosphate on the hydrangea leaves.

1.3 Lack of blooms

Why do some bigleaf hydrangea have little or no flowering at all? I can assure you that this is caused by the wrong pruning time and method.

Endless summer blooms on new and old wood. Other varieties bloom in the same way as oakleaf hydrangea, only bloom on old wood. Therefore, I will use different pruning methods and times to prune endless summer and other varieties of bigleaf hydrangea.

Endless Summer

Bloom twice:

Endless summer can bloom twice a year. I will prune it in early June if I want endless summer to bloom again in fall. Trim the flowering stems to 8-10 inches (20-25 cm) and remove stems that have not flowered or budded. Meanwhile, keep as many healthy green leaves as possible.

On the 15th day after pruning, endless summer usually grows new buds between 1 and 2cm long. If I plant hydrangea in a pot, I will immediately transplant it into a larger pot.

This pruning method will allow Endless Summer to bloom twice, whether planted in a pot or in the backyard. It is worth noting that the flowers will be relatively small in the fall.

It is not only endless summer that can bloom twice a year, but also Blushing Bride, L.A. Dreamin, and Blue Ocean can bloom twice a year.

If I only need endless summer to bloom once a year, I will prune them from July 20 to 30.

Bloom once

If I only need the flowers of endless summer to bloom the following year, I will prune them from July 20 to 30.

Other varieties

Other varieties of bigleaf hydrangeas, such as mophead hydrangea and lacecap hydrangea, require specific pruning methods. Before pruning, I will divide these hydrangeas into young and Mature plants.

Young plants

I trim the young plants in late May. From July 20 to July 30, I will prune them again. If I plant young plants in a pot, I transplant them into a larger pot every time I finish pruning.

The transplant aims to promote the growth of new stems and buds. And make the old stems strong to increase the number of flowers next year.

Mature plants

Some stems of mature plants are soft and lack toughness, so how do you trim them in this case?

Do not immediately trim these soft stems. The best solution is to provide partial shade to the plants, and we should extend the blooming period as long as possible.

The blooming period of bigleaf hydrangea ends in late July. When the blooming period ends, hard prune these soft stems, leaving only the stout stems. At the same time, retain as many healthy leaves as possible for photosynthesis.

After pruning, do not let the sunshine directly on these plants. Instead, it would be best to use 75%-80% shading cloth to block the light.

To remove thin and weak stems, perform a second pruning in late winter or early spring.

Pruning Macrophylla Hydrangea (bigleaf hydrangea) in early spring is better for supporting plant growth with nutrients in the soil.

Whether planted in a pot or the backyard, I will add some organic matter or replace the soil after pruning. For mature plants planted in flowerpots, I will transplant them into larger pots after pruning.

This practice aims to promote new growth so that pruned plants grow new stems and buds so that these new buds can bloom next year.

1.4 Fungal Disease

Fungal diseases like powdery mildew, rust, leaf spots, and anthracnose sometimes infect the bigleaf hydrangea. While we can't stop these diseases from happening, we can prevent these plant diseases. If your plant is already sick, the first thing to do is to cut off the diseased part. Then, you can use specific fungicides based on the situation.

Powdery mildew

Powdery mildew can cause the leaves of hydrangea to twist or even fall. Hydrangea with powdery mildew has a layer of white mold on its stems, leaves, and buds, like flour sprinkled on it. Poor airflow can lead to powdery mildew. This disease usually spreads during warm days or cool nights.

Increasing plant spacing and pruning intertwined stems can improve air circulation to prevent powdery mildew. Remove and burn up the diseased parts to prevent large-scale infection. It is worth noting that you must burn up the whole plant if the plant leaves have been seriously deformed or yellowed.

Rust disease

There are orange spots on the front and back of hydrangea leaves with rust disease as if they were rusty. The best way to prevent rust disease is to maintain good airflow and water the bottom of the plant to prevent water from splashing on plant leaves.

Leaf spots

Small, round, brown, or purple spots often appear on the hydrangea leaves. Excessive moisture causes these spots on the leaves, which we call leaf spots. The way to prevent leaf spots is the same as to prevent rust disease, which water from the bottom of the plant, not the top.

Anthracnose

Anthracnose leaves will appear with brown spots, and the center of the spots will turn gray and perforated. For hydrangea, this disease is a fatal fungal disease. When this disease occurs in plants, keep the environment ventilated, cut off diseased parts in time, remove dead plants, and destroy them.

1.5 Pests

Aphids

Aphids are pests that reproduce rapidly. They gather together to feed on plant sap. Aphids can spread other diseases to plants.

If ants climb up and down on the plant, it means it has aphids. Generally, I use insecticidal soap or yellow armyworm board to kill aphids.

Japanese beetles

The Japanese beetles especially like to live on the bigleaf hydrangea. They eat on leaves until leaves only have veins. Their larvae hide in the soil and bite the plant's roots until it wilt.

Neem oil can effectively eliminate Japanese beetles.

Spider mites

The spider mite is a kind of insect with a 0.2-0.4mm length. Generally, they gather on the back of the plant leaves. A web appears between the leaves when many spider mites are on the plant.

Spider mites feed on the sap from leaves, causing plant growth deformities.

Spider mites like dry and hot environments, so we can spray water on the back of plant leaves when they first appear. Of course, ladybugs can also destroy them. If there are many spider mites, I will use pesticides to eliminate them.

2.FAQs

Q: How do I select the perfect soil for hydrangeas?

A: When growing hydrangea, we should choose the soil with good drainage. I will mix peat moss, perlite, and manure according to 1:1:0.5. Peat moss provides water retention, perlite provides well-drainage, and manure provides organic matter.

Q: When is the best time to prune my Bigleaf Hydrangeas?

A: Besides endless summer, other hydrangea varieties must distinguish between young and mature plants before pruning. I prune young plants in late May and late July. I cut off the soft stems of mature plants in late July and prune the thin and weak stems in late winter or early spring.

Q: How can I change the flower color of my hydrangeas?

Soil pH	Flowers color
pH＜5.5	Blue flowers
5.5≤pH＜7	The color of the flowers is between pink and blue.
pH≥7	Pink flowers

In acidic soil, flowers are often blue. In alkaline soil, the flowers are pink. We want to change the color of the flowers, and we need to adjust the pH value of the soil.

We add aluminum sulfate to the soil to have blue flowers. Add lime to the soil to have pink flowers.

Q: What kind of sunshine environment does the bigleaf hydrangea like?

A: We should find the balance of sunlight so that we will neither sunburn the leaves nor lack sunlight. Bigleaf hydrangea likes the full sun of the morning. At noon, We need to provide shade for hydrangea.

Q: How often should I water my hydrangeas?

A: The easiest way to determine whether or not to water is to insert your index finger into the soil. When we feel the soil is dry, we use deep watering to let the water soak the soil thoroughly. We also use mulch for keeping the soil moist and controlling its temperature.

Q: How can I revive wilting hydrangeas?

A: If the lack of water causes the hydrangea to wither, then we should water the hydrangea immediately. We must let the water soak the soil thoroughly. At the same time, we should use transparent plastic bags to cover the whole plant to increase the humidity around.

3. Conclusion

Planting hydrangea is a long process. I will constantly learn how to care for bigleaf hydrangea in this process. Only when we devote ourselves to this learning will we cultivate a thriving hydrangea. I hope we can harvest the beauty that hydrangea brings to us.

At the same time, if you have any questions or thoughts, you are welcome to leave a message here. I want to communicate with you.

Bibliography:
Effect of aluminum on root morphology of Hydrangea macrophylla, Naumann, A., Kunz, U., Lehmann, H., Stelzer, R., Horst, W.J. (2001). Effect of aluminum on root morphology of Hydrangea macrophylla. In: Horst, W.J., et al. Plant Nutrition. Developments in Plant and Soil Sciences, vol 92. Springer, Dordrecht. https://doi.org/10.1007/0-306-47624-X_250
First report of natural infection of Hydrangea macrophylla by pepper mild mottle virus in Korea, Sung-Woong Kim, Ga-Eun Lee, Hyo-Jeong Lee, Hae-Jun Kim, Kwang-Yeol Yang & Rae-Dong Jeong, Received 01 February 2023, Accepted 20 April 2023, Published 02 May 2023, Issue Date August 2023, https://doi.org/10.1007/s42161-023-01394-1
Targeted generation of polyploids in Hydrangea macrophylla through cross-based breeding, Tränkner, C., Günther, K., Sahr, P. et al. Targeted generation of polyploids in Hydrangea macrophylla through cross-based breeding. BMC Genet 21, 147 (2020), Received 12 August 2020, Accepted 17 November 2020, Published 07 December 2020, https://doi.org/10.1186/s12863-020-00954-z
Stem and root rot in hydrangea caused by Pythium myriotylum and Globisporangium spp. and susceptibility of hydrangea cultivars, Nagashima, S., You, X., Uzuhashi, S. et al. Stem and root rot in hydrangea caused by Pythium myriotylum and Globisporangium spp. and susceptibility of hydrangea cultivars. J Gen Plant Pathol 87, 148–153 (2021), Received 19 June 2020, Accepted 06 March 2021, Published 12 March 2021, Issue Date May 2021 https://doi.org/10.1007/s10327-021-00989-9
Population Dynamics of Tetranychus Kanzawai (Acari: Tetranychidae) on Hydrangea, Gotoh, T., Gomi, K. Population Dynamics of Tetranychus Kanzawai (Acari: Tetranychidae) on Hydrangea. Exp Appl Acarol 24, 337–350 (2000), Issue Date May 2000 https://doi.org/10.1023/A:1006428503702

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.