What to do on our trees in December?

The cold has settled in France, a large part of the regions have suffered more or less significant frosts. In the northern regions, a large proportion of the trees have returned to overwintering after stockpiling. Others continue to impress us with their splendid colours in regions with milder climates.

Apart from a few species that are more sensitive to frost (azalea, loropetalum, etc.), most bonsai can cope with the cold of winter.

The major problem with freezing is dehydration.

A substrate that is frozen over a long period of time prevents the roots from absorbing water. As much as this is not a problem when temperatures become positive during the day, if they remain negative and over several days the roots can dry out and cause their loss or even the death of the tree.

Repotting

Repotting is not recommended for the vast majority of varieties from now on. It is best to wait until February/March/April to do these.

However, you can remove mosses and lichens from the surface of the pots. These are an ideal nest for pests.

Watering

As in the previous month, watering should be done sparingly. It is forbidden to water in freezing weather, or otherwise preferably in the morning (in positive temperature), or in the middle of the day, depending on the night's forecast. Also be careful that the entire root ball receives water. Indeed, with the dew effect and humid nights, the surface of the substrate can seem permanently damp and reassures us in the fact that we do not water, but it is very common for a large part of the root ball to be dry at the bottom of the pot.

Fertilizer

Fertilization is no longer necessary for outdoor varieties. Usually, plants no longer assimilate fertilizers below 20°, but for warmer and sunnier regions, this temperature can easily be reached in the pot.

Waist

For conifers, this is a good time to carry out large prunings, the installation of ligatures or even woodwork, such as shari or jin.

Deciduous trees have lost their leaves, it is also possible to prune the structure or install wire, ligature or guying. You can also wait for the buds to swell and prune around February/March.