The best felling time is midwinter, from December to the end of March, when the trees are frozen in dormant state. Low air humidity improves the quality of felled wood, too. It helps to avoid tensions and variations in colour. Alder and larch can be logged during the growing season as well. Their wood has a red tone that will become more intense.
In summer, deciduous trees are felled and left to dry in a pile, in which case they are not delimbed. This way the foliage will evaporate the moisture from the wood. The wood is dry when the leaves drop off.
In Finland, summer felling began at the beginning of 1970s. However, it is harmful for both nature and forest owners. Therefore, summer felling should be avoided in areas where there is vulnerable vegetation, for example in grassy woodlands, fresh and dry peaty forests with heavy moss and lichen cover, and deciduous forests.
Wood that is felled in the summer causes problems for the sawmill industry, because the wood needs to be protected with chemicals. Wood that is felled in the winter, on the other hand, is drier and lighter in colour. Therefore, it is higher in quality for both the sawmill industry and in the production of ground pulp.