Hydrangea 'Blue' (Hydrangea macrophylla) - garden hydrangea - 17 cm pot - Height 30 cm

The blue color of theHydrangea macrophylla depends directly on the soil acidity and the availability of aluminum in the substrate. In acidic soil (pH below 6), the flowers develop shades ranging from lavender blue to intense blue. In neutral or alkaline soil, they lean towards mauve or pink, because the aluminum becomes unavailable to the plant. To maintain a deep blue, incorporate an acidifying amendment (aluminum sulfate, fertilizer for blue hydrangeas) every spring and water with rainwater preferably rather than tap water which is often hard.

The best time to plant a Blue Hydrangea (Hydrangea macrophylla) in the ground is autumn, from October to November, which gives the roots time to establish themselves before the summer heat. Spring, from April to May, is also possible provided that regular watering is ensured throughout the following summer. Avoid planting during frost periods or in the middle of a heatwave. Prepare a planting hole at least twice as wide as the root ball, amend with compost and ericaceous soil if your soil is alkaline, then mulch the base immediately to retain moisture.

Hydrangea macrophylla is a species fundamentally adapted to partial shade or light shade. Direct sunlight for more than four to five hours a day, especially in the middle of the afternoon, causes the flowers to wilt quickly, the foliage to yellow, and severe water stress. The ideal exposure is bright but filtered light: under a large deciduous tree, against an east- or north-facing wall, or in the shadow cast by a hedge. In the South of France, almost complete afternoon shade becomes essential to maintain beautiful blooms throughout the summer.

In a pot or container on a balcony, 'Blue Hydrangea requires frequent and generous watering, as the limited volume of soil dries out much faster than 'in the ground. In hot weather, daily watering at the end of the day is often necessary: check by sticking a finger into the soil; 'if it is dry at a depth of 2 cm, you need to water. Preferably use 'rainwater or 'water that has been left to settle to avoid the 'addition of lime which changes the pH. Make sure the pot has effective drainage holes to prevent water from stagnating, 'which rots the roots.

The annual pruning of theHydrangea macrophylla is recommended but must remain light to preserve the flowering. At the end of summer or in autumn, remove the faded flower heads just above the first pair of well-swollen buds: this also protects the buds from winter frosts by serving as a screen. In spring, wait for the vegetative growth to identify the truly dead branches (no green buds), and cut them only at their base.

Hydrangea macrophylla is a hardy species that can tolerate winter temperatures down to around -15°C when planted in well-established ground. In France, it overwinters without any special protection in the vast majority of regions. However, the flower buds formed in autumn are more delicate than the plant itself and can be damaged by late spring frosts. In regions with harsh winters, it is recommended to apply a generous layer of mulch around the base (dead leaves, straw, bark).

B'lue Hydrangea pairs beautifully with o'ther mid- and sh'ade-loving plants that share its preference for cool, slightly acidic soil. Hostas with broad blue-green or variegated leaves form a magnificent carpet of foliage at its feet. Ferns (dryopteris, osmonde) add lightness and contrasting texture. Pink or white astilbes, which bloom at different times, extend the display from late June to August. For a shrubby effect, pair it with o'ther hydrangeas (H. paniculata, H.