Kupala's first serious literary attempt was Ziarno, a Polish-language sentimental poem which he completed around 1903–1904 under the pseudonym "K-a."
Kupala esimene tõsiseltvõetav kirjanduslik katsetus oli poolakeelne sentimentaalne luuletus "Ziarno", mis valmis umbkaudu 1903–1904 pseudonüümi "K-a" all.