A Complete Caring Strategy for Hydrangea Blooming Period

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1. Type of Hydrangea and Blooming Month

May to June (Late spring to early summer)

H. scandens or H. petiolaris (Climbing Hydrangea）
H. luteovenosa
H. serrata (Mountain Hydrangea)

June to July (Early summer to mid-summer)

H. macrophylla var. normalis (Lacecap Hydrangea)
Hydrangea macrophylla var. macrophylla (Bigleaf Hydrangea)
H. serrata subsp. yezoensis
Hydrangea arborescens (Smooth Hydrangea)
H. quercifolia (Oakleaf Hydrangea)

June to August (Summer)

H. involucrata

June to September (Early summer to early fall)

H. paniculata (Panicle Hydrangea, Peegee Hydrangea)

2. Sunshine

Knowing hydrangeas need full sun or shade when they're blooming is essential.

I must meet their sunshine needs if I want my hydrangea to bloom longer. Hydrangeas like different amounts of sunlight at different times during their blooming season, which lasts from May to September. Please let me show you how I meet the hydrangea demand for sunshine.

May and June

The sun is not very intense from May to June. So, I will make sure that the hydrangea has enough sunlight. If some hydrangeas do not showcase their original color or are still in the bud stage, they need full sun. The more sunshine there is, the brighter the flowers will be.

While some hydrangeas can bloom in the shade, the flowers of red H. serrata will turn white or not be brightly colored enough if they do not receive enough sunshine, such as "Japonica" and "Kurenai."

Moving them outside first to get full sun is best for indoor hydrangeas. Once the flowers are ripe, I can move them indoors.

July, August, and Mid-September

Before June ends, I will ensure that hydrangea gets full sun. After June, the sun becomes intense and can cause flowers and leaves to sunburn, turn yellow, lack water, and wither.

Watch out, bigleaf hydrangeas! Direct, intense sunlight can harm these plants. Bigleaf hydrangeas have large leaves, which results in water evaporating quickly from the leaves.

The roots of these plants cannot supply enough water to the leaves to keep up with the evaporation rate. As a result, the plant can be listless even if there is enough water in the soil. I call it a "false water shortage.”

So, I can set up a shade cloth that provides partial shade to ensure my plants stay healthy and bloom longer.

If you can't provide good shade for hydrangea, I suggest you plant oakleaf hydrangea and Smooth Hydrangea. These two kinds of hydrangea do not need shade. On the contrary, these two kinds of hydrangea need full sun.

Late September

The sun is no longer intense in late September. I will remove the shade cloth in late September and let Hydrangea restore to get full sun.

3. Pruning

I didn't even know how to judge if my hydrangea flowers had withered when I first growing them. I used to cut off the flowers only when they had completely died.

So when will the flowers of hydrangea wither? This time is tough to grasp.

In fact, As long as the flower hangs down and the back of the flower is up, it means that the flower has withered. At this time, I will prune the flowers as soon as possible. If I don't trim these flowers, it can badly impact the growth of new stems and the formation of new flower buds for next year.

So, it's vital to prune hydrangeas during the blooming season. When is the best time to trim? How do you prune?

Here, I would like to share my experience with you.

The blooming period and after blooming period pruning time of different hydrangea varieties

3.1 When is the best time to prune?

First, I will remember the end of August, the pruning deadline. At the latest, I will trim most varieties at this time. I may extend the latest pruning time to February of the following year for Panicle Hydrangea and Smooth Hydrangea.

After August, most of the hydrangea flower buds begin to sprout and differentiate. After germination and differentiation, I will no longer prune them. Otherwise, the hydrangea will not bloom next year.

Then when is the most appropriate time to trim? At this time, I will use the second principle: after the hydrangea blooms, if I prune it early, it will sprout new stems faster. On the contrary, the new stem will grow slowly.

Why is that?

The weather will get hotter and hotter from May to September, and the hot weather will slow the growth of Hydrangea.

So, after the hydrangea blooms, I will prune the young hydrangea as soon as possible. In this way, young hydrangea will sprout more stems faster. And in the growing season of the second year, it will have a more oversized crown and more flowers.

I don't mind when I prune the large hydrangea; timing is flexible. I can trim it earlier or later, but it doesn't matter. Because these large hydrangea have enough stems, I don't need them to grow more new stems.

In short, if I want my hydrangea to grow bigger, grow more stems, and bloom more flowers next year, I will prune it earlier.

The only downside of pruning the plants early is that it may reduce their bloom time. Generally, I will put the cut flowers in a vase. After all, these flowers are so beautiful that I can't bear to throw them away.

3.2 How do you prune?

I will consider two questions before pruning: one is space, and the other is whether my hydrangea is strong enough.

I will opt for heavy pruning to keep the hydrangea crown small indoors. For hydrangeas planted in the backyard, I will choose light pruning.

After the blooming period, pruning hydrangea can be done according to your needs.

I will opt for light pruning for hydrangeas with slender stems to help them retain more leaves for photosynthesis. And when I do some light pruning, plants get the chance to store enough nutrients. This helps them grow stronger stems in the next year.

For robust hydrangea, light or heavy pruning is not an issue. If I choose light pruning, I will prune to the thickest position of the stem. So that the new stems will be thick and the following year's flowers will not bend the stems.

Tips: Most varieties bloom once a year, except for Endless Summer, which can bloom both new and old branches. To prolong the blooming period, I will stop fertilizing when flowering. But after pruning, I will use high nitrogen fertilizer to hydrangea in time.

4. Conclusion

May is a particular month in Japan, and Mother's Day is the second Sunday in May.

When I lived in Japan, I saw that in May, there were many beautiful potted hydrangeas at the florist's shop. People could buy them as gifts for their mothers on Mother's Day.

Time flies, and now I live in the United States, I still grow hydrangeas in my backyard. Day after day, hydrangea goes from flowering to withering, and every change of color is surprising. I hope you can feel the beauty of hydrangea as well as I do. Have a nice gardening trip.

Bibliography:
Remontant Flowering Potential of Ten Hydrangea macrophylla (Thunb.) Ser. Cultivars. Adkins, J. A., & Dirr, M. A. (2003). HortScience HortSci, 38(7), 1337-1340. Retrieved Feb 5, 2024, from https://doi.org/10.21273/HORTSCI.38.7.1337
Hydrangea arborescens ‘Annabelle’ Flower Formation and Flowering in the Current Year, Huang, X.; Lyu, T.; Li, Z.; Lyu, Y. Plants 2023, 12, 4103. https://doi.org/10.3390/plants12244103
Temperature and photoperiod control of morphology and flowering time in two greenhouse grown Hydrangea macrophylla cultivars, Elin Fjellvang Nordli, Marianne Strøm, Sissel Torre, Scientia Horticulturae, Volume 127, Issue 3, 2011, Pages 372-377, ISSN 0304-4238, https://doi.org/10.1016/j.scienta.2010.09.019.
Flowering Performance of 21 Hydrangea macrophylla Cultivars, S.M. Reed; Journal of Environmental Horticulture 1 September 2002; 20 (3): 155–160. doi: https://doi.org/10.24266/0738-2898-20.3.155
Impact of lighting conditions during forcing on flowering time, morphology and postharvest transpiration of Hydrangea macrophylla, Terfa, M.T. and Torre, S. (2019), Acta Hortic. 1263, 405-412, https://doi.org/10.17660/ActaHortic.2019.1263.53
INFLORESCENCE DEVELOPMENT IN HYDRANGEA MACROPHYLLA, Uemachi, T. and Nishio, T. (2000), Acta Hortic. 515, 265-272, https://doi.org/10.17660/ActaHortic.2000.515.33
Architectural Development of Inflorescence in Hydrangea macrophylla cv. Hermann Dienemann. Galopin, G., Codarin, S., Viemont, J., & Morel, P. (2008). HortScience horts, 43(2), 361-365. Retrieved Feb 6, 2024, from https://doi.org/10.21273/HORTSCI.43.2.361
Study on the Flower Induction Mechanism of Hydrangea macrophylla. Liu, Y.; Lyu, T.; Lyu, Y. Int. J. Mol. Sci. 2023, 24, 7691. https://doi.org/10.3390/ijms24097691

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.