Old documents of the Garden show that the first part of the Garden was established near the present site of mud cypress trees and occupied 4 hectares of land and a small old building. This building and its successor have always been referred to as Pokerek. Older employees of the Garden told the story that this was because it was won in a poker game. Rumor has it that in 2011, Magdalena Swiąder and Lidia Gnatowska, who were working at the time, met with Wojciech Fangor, formerly living at the Janówek estate, who told them this story:
- Gronówek (the building on Prawwka Street) was ours, and Pokerowo, behind the ponds, belonged to other people we didn't actually know, and Kowarski (Prof. F. Sz. Kowarski, painter, sculptor, educator), who before the uprising went to Skierniewice, and I to Rabka, rented this house after the liberation, and he called it Pokerowo. In the winter, during the war, when we lived with Kowarski in Janówek, it was boring and we played poker for a little money. And when he was a loser, he would play until morning to play, but when he won, he was tired and went to bed.
The beginning of the Botanical Garden's organizational structure was the Laboratory of Crop Genetic Resources at the Department of Plant Genetics of the Polish Academy of Sciences, which was based in Skierniewice. Before the laboratory became permanently established in Powsin, the scientific staff used to come on Saturdays for seminars, which were just held in the "Old Pokerek." At that time the building was not sewered, so a duty officer was appointed, whose job was to bring water from the well and make tea for the colleagues. The well was located in the courtyard next to the building.