With their absolutely spectacular flowers, hydrangeas are fascinating plants that delight gardeners and nature lovers. While their cultivation is not complex, some questions often arise. It’s time to take stock.
Should hydrangeas be pruned? Yes, but… pruning depends on the type of flowering of each species. Some, like the common hydrangea (Hydrangea macrophylla), bloom on last year’s wood: so pruning them means removing the flower buds. For these varieties, it is better to avoid pruning and simply remove one branch out of four each year, cutting at the base the oldest or least vigorous ones.
On the other hand, other hydrangeas bloom on the wood of the year, such as the ‘Annabelle’ cultivar or panicled hydrangeas. These can be pruned short at the end of winter without risk. The flowering will be later and the inflorescences less numerous, but they will be significantly larger in compensation, sometimes requiring staking.
Can hydrangeas be grown in pots? Growing hydrangeas in pots is completely feasible over several years, provided that compact varieties are chosen and regular maintenance is ensured: watering, repotting or pruning.
Among the most suitable varieties for a 40 cm pot, we can mention ‘Tovelit’, very compact with its carmine pink flowers (60 x 60 cm), ‘King George’ in bright pink (80 x 80 cm), ‘Masja’ in bright red, or ‘Merveille sanguine’ with blood red flowers that bloom until the frost. ‘Sunday Fraise’, a smaller version of the famous ‘Vanille Fraise’, and ‘Annabelle’, particularly resistant to drought, complete this selection.
Why do my hydrangeas not stay blue? The blue or purple color of hydrangeas does not depend on the gardener, but mainly on the geology of the soil. To turn blue, these plants need two simultaneous conditions: acidic soil (pH below 6) and the presence of aluminum sulfate.
This is why hydrangeas naturally turn blue in areas like Brittany, Normandy, or the Basque Country, but remain pink in limestone regions like the Paris Basin. In limestone soil, calcium blocks the absorption of aluminum by the roots, and also deprives the plant of iron, causing the leaves to turn yellow.
