Horst Baeseler was born in Dresden in the southern part of what was then central Germany. His father was a pharmacist. He attended school at the city's prestigious , but his school days were prematurely terminated in February 1945 when the school was destroyed. The war ended in May 1945 and Dresden found itself in the Soviet occupation zone of what remained of Germany, controlled by the Soviet military. Four years later the entire "zone" was subsequently relaunched as a stand-alone East German state under Soviet sponsorship, the German Democratic Republic formally founded in October 1949. Baeseler trained between 1945 and 1948 as a gardener at the Tree School in . He then started work as a gardener, focusing on herbaceous shrubs and trees. He also continued to train, now with Johann Greiner at the Horticultural Academy in Pillnitz. In 1951 he took a part in a machinery training course for gardeners in Quedlinburg.