When it comes to the garden, we don't talk about four but ten seasons. This is the principle of the phenological calendar. Find out here what it's all about.
The year consists of four calendar seasons. However, the gardener knows another classification: namely the phenological seasons. These are not fixed in the calendar, but are based much more on the course of nature. The so-called indicator plants are decisive for the onset of the seasons. Nevertheless, the phenological calendar follows a different rhythm from year to year and depending on the region.
Historical and Basic
The word phenology comes from the Greek and literally means "study of phenomena". This is a separate science that was founded by Carl von Linné in the 18th century. The Swedish naturalist established a flowering calendar and established a network of people in Sweden who made phenological observations.
In Germany, phenology began to gain ground in the 19th century. Today, around 1,200 voluntary observers across the country provide the German Weather Service with useful information. The data is then archived and processed at the company headquarters in Offenbach. A direct evaluation is carried out, for example, for the pollen information service. Longer-term analyzes are relevant to science.
What are the benefits of the phenological calendar?
The Phenological Calendar is the result of decades of research. Dividing the year into ten seasons instead of the usual four allows for a more precise division of the garden year, taking into account climatic and regional differences. At the same time, conclusions can be drawn about the development of nature in the individual regions. This horticultural calendar is not fixed to the exact day, but adapts to the development of nature in the respective observation area.
The phenological data are compared to the established astronomical and meteorological values. are in agriculturethe phenological information, for example, is an important indicator for planning and coordinating the upcoming work.
The determined data also allow conclusions to be drawn about the general climatic development. In the 20th century, for example, an earlier start of spring could be registered. Science brings this together with the influences of global climate change.
Basically, the phenological calendar is based on the development of the indicator plants. After a mild winter, early spring breaks out in some regions as early as January. The statistics of the data then allows conclusions to be drawn about the development of climate change and helps farmers and hobby gardeners to plan upcoming work on the fields and in the gardens.
What kind of indicator plants are there?
A number of plants are used to determine the phenological seasons. These include:
| Pointer Plant Group | individual representatives |
|---|---|
| Wild Plants | • Birch • Hazelnut • Blueberry • Dandelion • European Beech • Snowdrop • Black Elderberry • English oak • Rowanberry |
| Crops | • Apple • Apricot • Corn • Corn • Plum • Canola • Redcurrant • Sunflower • Grapevine • Sugar Beet |
| Ornamental plants | • Lilac • Forsythia • Mockingbird • Witch Hazel |
How is the phenological calendar classified?
The division is made into ten seasons. These are defined by the flowering and maturity of corresponding indicator plants. The duration of the seasons varies and can therefore only be given as an estimate in the following.
| Season | approximate period |
|---|---|
| Early Spring | 22. February to March 29 |
| First Spring | 30. March to April 30 |
| Full Spring | 1. May to May 29 |
| Early Summer | 30. May to June 21 |
| Midsummer | 22. June to August 4 |
| Late Summer | 5. August to August 27 |
| Early Fall | 28. August to September 21 |
| Full Autumn | 22. September to October 15 |
| Late Autumn | 16. October to November 30 |
| Winter | 1. December to February 27 |
Which indicator plants are availablefor each season?
The following indicator plants are used to determine the phenological seasons:
| Season | Pointer Plants |
|---|---|
| Early Spring | • Snowdrop • Hazelnut • Snowflake • Willow • Black Alder • Winter Jasmine • Sycamore |
| First Spring | • Forsythia • Fruit trees • Berries • Birch • Linden • Maple |
| Full Spring | • Apple • Lilac • Horse Chestnut • Oak • Hornbeam |
| Early Summer | • Black elder • Black locust • Rye • Grasses • Hawthorn |
| Midsummer | • Linden • Redcurrant • Chicory • Rye |
| Late Summer | • Rowanberry • Heather • Early Apple • Pear • Autumn Anemone |
| Early Fall | • Black elder • Autumn crocus • Horse chestnut • Hazelnut • Pears |
| Full Autumn | • Potatoes • Walnut • Horse chestnut • Quince • European beech • Apples • Turnips |
| Late Autumn | • Horse Chestnut • English Oak • Winter Cereal |
| Winter | • Winter Wheat |
What are the special features of the individual seasons?
The individual phenological seasons are determined by the development of the assigned indicator plants. Here is a small overview:
❍ Early Spring:
The blooming of hazelnuts, snowflakes and snowdrops heralds the beginning of spring. The winter jasmine is in full bloom. In the Alpine region, the sycamore maple begins to sprout. Early spring ends when the willow blossoms.
❍ First Spring:
The first spring begins with the forsythia blossom. Gooseberries and currants are also blooming. After the birch and horse chestnut have sprouted, lime, maple and beech follow. The first spring comes to an end with the blossoming of cherries, pears and plums.
❍ Full Spring:
Lilac and apple trees bloom in full spring. Oak and hornbeam begin to sprout. Later the first raspberries bloom. Potatoes and sugar beets sprout in the fields.
❍ Early summer:
The flowering of the meadows and fields reaches its peak. Black elder, goat's beard and hawthorn are in bloom. The grain develops the first spikes and panicles. The winter rye is blooming. The hay willretracted and for allergy sufferers the hay fever season begins.
❍ Midsummer:
The currants are getting ripe. Potatoes, small-leaved lime and chicory are in bloom. Winter barley cutting in the fields begins. Winter wheat, oats and winter rye are also brought in.
❍ Late Summer:
Rowberries, Early Apples and Rock Pears can be harvested. The flowering season for heather and autumn anemone begins. While the grain harvest is largely over, the second hay harvest begins.
❍ Early Autumn:
The black elder is ripening and the horse chestnuts are bursting and falling from the trees. Harvest time is also beginning for hazelnuts. Plums and pears are also ripe. The autumn crocus is in bloom.
❍ Full Autumn:
The leaves of beech, ash, alder or horse chestnut begin to discolour. Leaf fall has already started on the fruit trees. Potatoes, quinces, apples and walnuts are harvested.
❍ Late Autumn:
If the horse chestnut or English oak also begins to drop their leaves, the phenological late autumn sets in. The winter grain is growing. The growing season is over. With the end of the fall of the leaves, the late autumn is also over.
❍ Winter:
Winter begins with the emergence of winter wheat. The dormancy lasts until hazel flowering heralds early spring and the phenological cycle starts all over again.
Gardening according to the phenological calendar
If the gardener only follows the calendar seasons, he often experiences a nasty surprise. The ground is still frozen and does not allow the seed to be planted. Freshly planted plants freeze to death because the danger of night frosts has not yet been averted. This cannot happen if you measure vegetation development. For example, you can use the forsythia blossom as a guide. Then you can reach for the rose scissors because there is no longer any risk of frost.
Gardening in the phenological course of the year
| Season | upcoming work |
|---|---|
| Early Spring | • Pruning hedges> • Pruning fruit trees • Sowing summer flowers |
| First Spring | • Pruning berry bushes • Pruning fruit trees • Sowing summer flowers • Pruning roses |
| Full Spring | • Laying the lawn • Cutting spring bloomers • Sowing summer flowers • Bulb and tuber plantsset |
| Early Summer | • Laying the lawn • Cutting hedges • Cutting spring flowering bulbs • Sowing summer flowers • Sowing biennial plants • Harvesting hay • spin honey |
| Midsummer | • Pruning fruit trees • Pruning berry bushes • Pruning roses • Sowing biennial plants |
| Late Summer | • Pruning hedges • Pruning fruit trees • Planting bulb and tuber plants • Harvesting grain |
| Early Fall | • Pruning hedges • Pruning fruit trees • Laying the lawn • Planting bulb and tuber plants • Harvesting fruit |
| Full Autumn | • Laying the lawn • Planting bulb and tuber plants • Harvesting fruit |
| Late Autumn | • complete final work • apply antifreeze |
| Winter | • Prune fruit trees |
Plant observer at work
Around 1,200 plant observers work on a voluntary basis and help the German Weather Service to collect the phenological data. Plant development data is collected and transmitted throughout the growing season. The observations are made within a maximum radius of two kilometers from the house.
The German Weather Service provides information on how to proceed with the observation on its homepage. Interested nature lovers can register there as observers and start observing the plants in the coming growing season. Also here is an interesting video from the German Weather Service. It explains the importance of monitoring plant growth for weather advice and climate monitoring:
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If you would like to delve more deeply into phenology and the ten phenological seasons associated with it, we have three book recommendations for you here: