When Do Hydrangeas Bloom? A Detailed Guide to Their Blooming Period

Hydrangea is a famous ornamental plant of the Yangtze River basin, also known as Eight Immortals flower, powder-ball flower, grass hydrangea, etc. Its flowers are large and beautiful in color, with full, big and lovely flower forms, and the flower color can be red or blue, delighting the eye and refreshing the mind. Hydrangeas were planted in the Jiangnan gardens built during the Ming and Qing dynasties, and the parks built in the early 20th century could not do without hydrangeas in their plantings either. Now let us take a look together at when hydrangeas bloom!

When do hydrangeas bloom?

Hydrangeas generally bloom from June to August, and the time from flowering to fading is about 25 days. The flower color of hydrangea is pink, light blue or white, but the color of hydrangea changes with the pH of the soil or medium. To deepen the blue, aluminum sulfate can be applied during the bud formation stage; to maintain pink, lime can be applied to the soil.

Why do hydrangeas fail to bloom?

1. Too much nitrogen fertilizer: In the early stage of flower bud differentiation, hydrangeas mainly need nitrogen fertilizer, and during the differentiation stage mainly phosphorus fertilizer. However, if nitrogen and phosphorus fertilizers are applied excessively in autumn and winter, it will cause nutrient excess in the plant, inhibit growth, make flower bud differentiation difficult, and affect flowering the following year.

2. Too little light: Household cultivation of hydrangeas is limited by conditions and receives less light, which causes leggy leaves and poor growth. The leaves consume too many nutrients, so there is insufficient nutrition during flower bud differentiation, affecting flowering.

3. Too much light: Hydrangea is a short-day plant, and during the flower bud differentiation stage the light period must not exceed 10 hours. For Eight Immortals flowers kept indoors, long periods of indoor lighting at night increase light exposure and affect flower bud differentiation.

4. Improper pruning: The flowering period of hydrangea is from June to August. After the flowering period, the flower branches should be pruned to reduce nutrient loss. If the plant grows too vigorously and is heavily pruned again in early spring, it is difficult to form flowering branches from June to August, resulting in reduced or no flowering.

How should hydrangeas be grown properly?

1. Soil: Hydrangea prefers loose, fertile, well-drained sandy loam, but changes in soil pH greatly change the flower color of hydrangea. To deepen the blue, aluminum sulfate can be applied during the bud formation stage; to maintain pink, lime can be applied to the soil.

2. Watering: The potting soil of hydrangea should remain moist, but watering should not be excessive. Especially in the rainy season, pay attention to drainage to prevent root rot caused by waterlogging. In winter, indoor potted plants are better kept slightly dry. If too wet, the leaves are prone to rot.

3. Light: Hydrangea is a short-day plant. In ordinary cultivation, avoid direct scorching sunlight, and 60-70% shade is ideal. Proper shading when sunlight is too strong in midsummer can extend the flower-viewing period.

4. Temperature: The suitable growth temperature for hydrangea is 18-28°C, and the winter temperature should not be lower than 5°C. Flower bud differentiation requires 6-8 weeks at 5-7°C. A temperature of 20°C can promote flowering, and maintaining 16°C after flowers appear can extend the flower-viewing period. Note that high temperatures make the flowers fade quickly.

5. Fertilizing: Hydrangea should generally be given 1 application of dilute cake fertilizer water about every 15 days. To keep the potting soil regularly acidic, 0.2% ferrous sulfate can be added when applying liquid fertilizer to turn it into alum fertilizer water for irrigation, and during the bud stage, 1-2 applications of 0.5% superphosphate soaking solution should be added.

6. Pruning: After hydrangea blooms, pay attention to removing the flower stems to promote new branches. Proper pruning can maintain a graceful plant shape. In early spring in March, diseased and withered branches and weak slender branches should be cut off from the base, retaining 3-5 healthy main branches and cutting them back, leaving 2-3 buds on each branch.

7. Pests and diseases: Hydrangea mainly suffers from wilt disease, powdery mildew and leaf spot disease, which can be prevented and controlled by spraying 600 times dilution of 65% zineb wettable powder. Pests include aphids and mirid bugs, which can be killed by spraying 1500 times dilution of 40% omethoate emulsifiable concentrate.

8. Repotting: Hydrangea generally needs to be repotted and have its soil changed once a year. When repotting, cut off rotten roots, decayed roots and overly long fibrous roots. After moving the plant into a new pot, firm the soil, water thoroughly, place it in a shaded place for about 10 days, and then move it outdoors for normal management.