Roses, magnolias and azaleas bloom in November. What is responsible for this?

The first decade of November is behind us, and in some gardens in Warsaw and near Warsaw, single, opening buds have appeared on magnolias and azaleas. Roses are also blooming. Such a view may be puzzling, especially since the flowering period of these plants is associated with warm seasons. We asked experts whether such a phenomenon in the penultimate month of the year is something that normally happens at this time.

– Magnolias and azaleas went through a lot of stress, it was hot and dry, and now we have such a prolonged period of cold and wet period. This caused some of the buds of these plants to open because they receive mixed signals, as if it were spring, i.e. they were awakened from dormancy – said Dr. Wojciech Podstolski, curator of the plant systematics department and the arboretum at the Botanical Garden, in an interview with tvnmeteo.pl University of Warsaw.

He is echoed by Professor Arkadiusz Nowak, director of the Botanical Garden of the Polish Academy of Sciences in Powsin.

– In the case of magnolias, these are mountain species from southwestern China. When the cold came, the buds and their physiology seemed to hibernate, they felt it was colder, and then when it suddenly got a little warmer for two weeks, about 10-12 degrees Celsius, they thought it was spring – he explained .

Wojciech Podstolski added that in the case of magnolias and azaleas, full flowering will not occur. – They are rather single flowers. And only some buds open – he noted.

Flowering occurs at this time of year. – All flowers and plants take risks, just like us. We are also an organism that takes risks, so this is a fairly standard phenomenon, but the real question is about frequency, repeatability and the number of species that do it. Because it is puzzling – added Arkadiusz Nowak.

As he emphasized, it is most often the case that naturally in Poland about 5-10 percent of taxa, i.e. groups of organisms, can do this, but the lengthening growing season, periods of warmth or lack of frost make the plants think that it is “okay” and ” You can try to bear fruit again.”

– This usually doesn't work. These risk takers die or do not die, but invest resources and lose. But this is a phenomenon typical of nature in general, because it cannot tolerate a vacuum, so if there is a chance to bloom and produce offspring, it obviously tries to do so. However, the frequency, the number of species that do it, the abundance, what part of the population blooms for the second time, all this is related to climate change and these observations are carried out by physiologists, botanists, geobotanists and it is evident that these are really serious percentages. It's not like it's half a percent, it's about a 15-20 percent increase compared to 10-20 years ago, the expert explained.

These types of organisms respond to heat, frost and day length. – If these are plants that can bloom when the day is short, but warm and without frost, then these are the species that do it. Sometimes it works because they manage to bear fruit and seeds. In most cases, unfortunately not. However, this is not an extremely rare phenomenon. This has been happening for years, but it is actually increasing – said Nowak. According to the expert, earlier flowering was observed in the garden in Powsin, which – as he admitted – is related to earlier spring and climate warming. – It is believed that plants around the world start flowering an average of 2.9 days earlier every decade. In Powsin, mountain species started flowering 19 days earlier, i.e. almost three weeks, 20 years earlier. This is a very serious change. If serious changes occur in spring, these changes are, of course, more and more serious in autumn and are certainly related to climate warming – emphasized the expert.

Not only did magnolias and azaleas appear in the gardens, but also roses bloomed. In the case of the latter, we are not dealing with anything unusual – this is due to the characteristics of the variety of these plants.

– In the case of roses, flowering at this time is normal, because modern garden varieties bloom until there is frost. They can bloom two or three times during the season, they have such waves. The first flowering takes place in early summer and then in summer, and then in late autumn, if the season is long enough – assured Wojciech Podstolski. He added that the roses, if there were no frost, could probably bloom in December. – A few years ago it was like that, winter didn't come for a long time. I remember that after the New Year we collected several flowers in our garden – said an employee of the Botanical Garden of the University of Warsaw.