Popular species of bouquet hydrangea are rather resistant to frost and winter weather conditions. Hydrangeas tolerate negative temperatures quite well, which is why they are so eagerly grown in Poland. They bloom profusely in spring and summer and can bloom until late autumn. However, sometimes the hydrangea does not bloom. A Japanese friend showed me why this might be happening. Many varieties of hydrangeas bloom on last year’s shoots. If they freeze in winter, the hydrangea will not bloom in spring.
Hydrangeas – frost resistance
They have different frost resistance:
- Garden hydrangea can be the most sensitive and requires careful protection.
- Bouquet and bush hydrangeas are more resistant and sometimes cope better in colder conditions.
- Vanille Fraise can withstand as much as -28°C if planted in a sheltered, sunny spot.
- Little Lime, Grandiflora and Limelight tolerate cold down to around -30°C.
How to prepare hydrangeas for winter?
First of all, it is worth knowing that you should not use protection too early. It is best to wait with this procedure until the first frost. Lower temperatures will help harden the bush and make the hydrangea more resistant to weather conditions. During this time, watering and fertilization should be limited so as not to artificially extend the growing season. Otherwise, the plant will not be ready for winter and may quickly begin to wither. According to a Japanese friend, the best time to prepare hydrangeas for wintering is the end of November. During this time, you should take special care of two places on the hydrangea. The first of them are the lower shoots and roots. They must be properly protected against freezing. The best solution for this is a mound of bark made around the roots. Another important step in preparing hydrangeas for winter is to protect the shoots. They should be wrapped thoroughly and tightly with agrotextile. The material perfectly protects against frost and wind, and also protects against moisture loss. This way, the hydrangea will survive the winter and will be ready to bloom in spring.
Autumn is a key moment. Here are the steps that are good to carry out in the coming months:
- Gradually limit watering – as it cools down, we stop watering intensively so that the plant can “harden off”.
- Waiting for the first frosts – only when they come do we start proper protection.
- Piling – cover the lower shoots and roots with a layer of pine bark or a mixture of soil and compost (or just soil).
- Wrapping with agrotextile – after securing the plants with a mound, they are wrapped with agrotextile to protect against moisture loss and additional cold.
- Hanging protective covers – it is worth tying up the shoots or “clothing” them with non-woven fabric so that they do not break under the weight of snow or ice.
- Stopping watering in winter – during frosts, it is sometimes better to leave hydrangeas dry to prevent the roots from freezing.
How to protect hydrangeas in pots?
require special care in autumn because their root system is more susceptible to frost than in plants growing in the ground. When the temperature begins to drop, it is worth moving the pots to a sheltered place – for example, to a veranda, an unheated greenhouse or a garage with a window, where the temperature remains above freezing, but not too high. If this is not possible, the container should be well insulated by wrapping it with straw, jute or agrotextile, and put Styrofoam underneath to protect the roots against frost. It is also worth protecting the upper part of the plant by creating a light cover of air-permeable non-woven fabric. In winter, hydrangeas in pots are watered very sparingly – just enough to prevent the soil from drying out completely. Too moist soil may freeze and damage delicate roots. In early spring, when the risk of frost has passed, the pots can be gradually placed outside and the plants can be pruned and fertilized to encourage them to grow again.
Plants in pots are more susceptible to freezing of their roots because the soil in the container cools down faster. This is why:
- Cover the pots with a layer of Styrofoam or straw – insulation from the cold at the bottom is essential.
- Move the plants to a quiet place, such as an unheated greenhouse, sheltered terrace or shed, with access to light.
- Wrap the upper part of the hydrangea with agrotextile, also securing the top of the pot.
- Keep watering to a minimum – avoid watering during frosts, and only in spring gradually “wake it up”: water moderately, start fertilizing and prune dry shoots.
