Oilseed rape (Brassica napus) is one of the crops that transform numerous landscapes into vast seas of flowers. The duration of the flowering period can be influenced by various factors.


Rapeseed is sown for the previous year’s harvest. After the winter, the Brassica napus usually flowers from April. If the weather is cool until early spring, the start of flowering can be delayed until May. Therefore, in most cases, this also depends on the location region. In regions with milder temperatures, the flowering season usually starts earlier than in cooler areas with “harder” winters and slower temperature increases in spring.

duration of the flowering period

Generally, oilseed rape flowers for a period of four to six weeks. The months of May to July are officially considered to be the main flowering period.

A distinction must be made between:

  • Summer rape

The summer variant is sown in the previous late summer and usually flowers first in April, at the latest in early May. The “conversion” to the pod often begins at the end of May.

  • Winterraps

Depending on the weather conditions, winter rape often starts flowering later than summer rape. The middle/end of May is not uncommon, especially not at cooler altitudes. On the other hand, oilseed rape often flowers well into July if the conditions are ideal. These include, above all, soil quality and moisture.

Note: Winter rape is mainly cultivated in Germany.

signs of flowering end

The flowering period is officially over when the plant sheds its leaves. Then the pods form from the flowers. This is where the rapeseed grains develop, which are harvested because of their high oil content.

Tip: If you can get hold of a few dark rapeseed pods, you can easily use them to make the popular rapeseed oil in your own kitchen.

Influence on flowering times

  • humidity

If it rains frequently and well dosed during flowering, this can extend the flowering period. So it happens that the flowering lasts up to two weeks longer and the second flowering lasts until August.

  • dryness

Prolonged drought can severely shorten the flowering period. Wilting occurs, flowers dry up and, in the worst case, the plants die. If the flowering period begins with a high level of drought, a significantly lower number of flowers and the duration of flowering can be expected.

  • pest infestation

As in almost every area of ​​cultivation, pests can have a major impact on growth and associated flowering.

Risk of confusion with mustard plants

Yellow blooming fields are often irritating, filling the landscape with color from late summer to autumn. Many are wondering if these are rapeseed blossoms. The answer is no! These are mustard plants whose flowers are very similar to rapeseed flowers. In addition to a different flowering time, the oilseed rape plant and its flowering can be easily distinguished from mustard plants by additional features:

  • Rapeseed leaves have fewer jags
  • Rapeseed stalks mostly bare with a maximum of light down
  • Rapeseed blossoms smell very intense
  • Formation of rapeseed flowers from bottom to top

frequently asked Questions

At the beginning of the flowering period in April, pollen counts less often. The situation is different during the main flowering period between May and July. Allergy sufferers should better avoid rural regions with rapeseed cultivation during this period.

In the case of rape, flowering first begins on the main shoots. Only later do flowers form on the side shoots. This can lead to an irregular formation of the pods, because the flowering period is correspondingly longer on the side shoots than on the main shoots.

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