Hydrangeas

Hydrangeas are generous, strong and extremely adaptable plants. They love shade, but also grow well in the sun, they thrive in almost any type of soil, and the only two essential conditions for their cultivation are a regular water supply and good drainage.

A rich, fertile soil is preferable to a sandy one that is poor in humus, which can still work with the addition of a compost made of leaves, shredded bark and manure. The materials that allow hydrangeas to grow and thrive are therefore extremely easy to find: acidic peat, shredded bark or even prunings from bushes and thin tree branches cut into small pieces.

They are not afraid of harsh winters and generally withstand temperatures down to six or seven degrees below zero, making cultivation easy even where the winter climate is quite harsh.

Pruning hydrangeas

The topic of pruning is fairly straightforward. As for H. macrophylla, which blooms on the previous year's wood, pruning should be limited to cleaning up dead material, removing old flowers and cutting the weakest stems by removing the last pair of buds.

The common opinion is that the old flower should not be removed until spring, because it is believed to protect the new shoot; however, lacecaps lose almost all their flowers with the winter frost. It is also good practice, for plants that are five to six years old, to remove about a third of the shoots at ground level so as to let light into the interior and allow good lignification and vigor (usually the oldest shoots are removed).

As for H. paniculata and H. arborescens, which bloom on the current year's wood, two buds should be left at the base of each stem (February-March), setting the stage for flowering with very large panicles. Climbing varieties, on the other hand, require limited pruning, which serves mainly to contain their growth.

For H. aspera, H. serrata, H. involucrata and H. quercifolia, only tidying-up pruning is needed. Pruning is not essential for hydrangeas: if left to grow naturally (limiting yourself in spring to removing dry branches and spent flowers) you will have large, exuberant bushes with irregular shapes, abundant flowering and smaller-sized blooms.

Hydrangea propagation

As for propagation, except for some more problematic species (H. aspera, H. seemani), hydrangeas reproduce excellently by cuttings, to be taken from April to October. The root division method should not be overlooked either, as it is easy and reliable, and lastly, the seed sowing method (November-December) which, while giving satisfactory results, does not guarantee the purity of the cultivar.

Hydrangea soil

Somewhat more complex is the topic of pH, which determines the acidity level of the soil and consequently determines the color of the inflorescences, although this variation only applies to H. macrophylla and H. serrata.

Hydrangea inflorescence

Hydrangeas are very different from one another, both in growth habit and in their inflorescences. These do not have petals, but rather sepals that have modified themselves by becoming colored. What we call the "flower" of the hydrangea is actually a cluster of tiny flowers, made more prominent by the colored sepals.

Within the inflorescence, we can distinguish between sterile flowers and fertile flowers. The former are those with large, very showy sepals. The others are barely noticeable. Sometimes the inflorescences contain only sterile flowers (in macrophylla mophead, large rounded inflorescences), other times both (in those with a lacecap form, flat inflorescence).

There are also the 'paniculate' types in which the flower cluster takes the shape of a panicle: they contain both sterile and fertile flowers. Increasingly varied inflorescences can be found: with only the petal margin colored, with small and curved petals, or ones that appear almost curly.