Phenological Calendar

Contrary to the astronomical seasons, the phenological periods are not bound to fixed dates. Yearly periods are determined by observations from nature. When, for example, the black elderberries ripen, it is time to say goodbye to summer. Snowdrops , on the other hand, initiate an early spring.

10 Seasons

The phenological calendar consists of 10 seasons: early spring, mid spring, late spring, early summer, mid summer, late summer, early autumn, mid autumn, late autumn and winter. The flowering, fruit ripening, leaf coloring or leaf fall of certain plant species - so-called indicator plants - mark the beginning of a new phase of the year.

Example of a Phenological Calendar
Example of a Phenological Calendar (Image: Sarah Arnold)
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Example of a Phenological Calendar
Example of a Phenological Calendar (Image: Sarah Arnold)

Early spring
Snowdrops and blooming hazel bring news of early spring. Winter is over.

Mid spring
Around April we have first spring in our regions. It begins when the forsythia flowers and when the gooseberries unfold their leaves.

Late spring
In full spring the plant development is in full activity. This season is initiated by the blossoming of the apple tree and when the stem oak develops its leaves.


Early summer
The early summer usually arrives in June. The black elderberry is in bloom. This is also the time of the hay is harvested and the beekeepers hurl the blossom honey after the rape or robinia blossoms.

Mid summer
During this hot period the large-leaved linden flowers and the currants ripen and the grain harvest gets started.

Late summer
Summer is coming to an end when early apple varieties (such as the clear apple) are ripe to be picked. Mountain ahs has also reached fuit maturityand winter rye and winter wheat are now being harvested.


Early autumn
Around September the big harvests are brought in. Among other things, black elderberries and cornelian cherries ripen, which signals the early autumn.

Mid autumn
We are in full autumn when the first fuits of the horse chestnut and oak are ripe and fall from the tree. The fruit harvest is now still being completed. Towards the end of this phase, the leaves of most deciduous trees turn a red-gold colour.

Late autumn
As soon as the foliage of the pedunculate oak turns an autumnal colour and the mountain ash sheds its leaves, late autumn begins. The winter grain rises and soon the vegetation will come to rest.


Winter
The falling leaves of the stalk oak, the late ripening apple and the needle fall of the European larch mark the beginning of the phenological winter. Nature remains in hibernation until the following spring, even if periods of mild temperatures should occur in winter. That way domestic plants protect themselves from possible frost.


References and further information

Deutscher Wetterdienst DWD (Phenological Seasons)
MeteoSchweiz (Spring index)

Indicator Plants in Spring

Hasel Kätzchen

Hazel bush

Forsythie Blüten

Flowering forsythia

Apfelblüten

Apple blossoms

Indicator Plants in Summer

Holunderblütenstand

Blossom of the black elderberry

Blüten der Sommerlinde

Flowering large-leaved linden

Klaräpfel

Ripe clear apples

Indicator Plants in Fall

Fruchtstand des Schwarzen Holunders

Ripe elderberries

Rosskastanie

Ripe horse chestnuts

Eichenblätter im Herbst

Red-gold leaves of the pedunculate oak

Indicator Plants in Winter

Stieleiche im Winter

Bald English oak