Hydrangea is a plant with discreet and timeless beauty, which never goes out of fashion and which has the extraordinary ability to transform a garden into an enchanted corner, where large colored inflorescences reign supreme. With the arrival of winter, even these majestic plants require attention, however, since the ability to survive the frost varies significantly depending on the variety: not all hydrangeas, in fact, face the cold with the same resilience, and understanding the specific needs of any type is essential to ensure that the plant can bloom vigorously the following year.
Rusticity and resistance: the starting point
Most of the hydrangeas grown in our gardens can be considered rustic, a characteristic that makes them able to resist low temperatures without suffering significant damage, although this resistance is not uniform. Some varieties, such as panicle hydrangea (Hydrangea paniculata) and the viburnum hydrangea (Hydrangea arborescens), show a remarkable tolerance to frost, an aspect that allows them to adapt even to the coldest regions. In contrast, flat hydrangeas or newer hybrid varieties are often more vulnerable and require additional protection.
One aspect that many overlook is the role of the substrate. Plants placed in the ground are generally more protected than those grown in pots, as the soil acts as a natural insulator, preserving the roots from freezing.
Potted plants: a challenge in its own right
Potted hydrangeas are more vulnerable than those grown in flowerbeds or borders. The limited amount of soil surrounding the roots offers little protection against frost, making these plants particularly vulnerable during the winter. A common mistake is to move the pots inside homes, where the hot and dry climate favors the attack of parasites, such as scale insects, and interrupts the plant’s natural winter rest cycle.
To protect potted hydrangeas outdoors, it is advisable to wrap the containers with insulating materials, such as jute, or coconut mats. An often overlooked detail is the importance of placing the pot on an insulating base, such as a polystyrene board, to prevent frost from penetrating from below.
Young plants: fragility and special attention
Newly planted hydrangeas, regardless of the variety, require special care during the first winters. This is because the roots, still in the developing phase, are less able to resist extreme temperature changes, which makes an additional layer of protection necessary: mulches of leaves, compost or bark can be placed around the collar of the plant to ensure insulation effective.
A curious anecdote: some gardeners suggest using Christmas baubles to mark young plants, so that they are easily identifiable under the snow, a practical solution that can also add a touch of magic to the garden during the cold season.
Intense frost and additional protections
In regions characterized by particularly harsh winters, not even the most resistant varieties can be left completely exposed. Therefore, covering the foliage with a fabric, or with a winter fleece, represent excellent solutions for protecting the shoots and preserving the structure of the plant. Also remember to avoid autumn pruning: uncut branches offer a natural barrier against the cold, while new cuts can expose the internal tissues to damage caused by frost.
A lesser-known but very useful aspect is not to water hydrangeas during the evening hours during periods of intense cold, given that stagnant water can quickly freeze and cause irreparable damage to the roots.
Less resistant varieties: alternative strategies
As previously noted, not all hydrangeas can be left outdoors, especially those from milder climates. The large-leaved hydrangea (Hydrangea macrophylla), for example, is particularly famous for its sensitivity to frost. In these cases, a protected space such as an unheated greenhouse, or a basement with a stable temperature around 5°C, can make the difference.
Do you want practical advice? Make sure that the environment chosen for wintering is well ventilated, because excessive humidity could encourage the development of mold and actually compromise the health of the plant.
An eye to the future: March and the vegetative growth
With the arrival of spring, hydrangeas begin to awaken from hibernation: this will be the ideal time to remove any protections and evaluate the general state of the plant. To check the vitality of a branch there is a simple method, which consists in lightly scraping the bark with a nail: the presence of green tissue indicates that the shoot is still viable.
For varieties that flower on the branches of the previous year, such as hydrangea macrophylla, you must absolutely avoid drastic pruning at the beginning of the season, while on the contrary, panicle hydrangeas can benefit from vigorous pruning, which stimulates the production of new flower shoots .
