Plant genome sequencing based on long reads has increasingly been applied also to tree species in recent years. A crucial step in these genome projects is the successful extraction of high-molecular-weight DNA in high quality and sufficient quantity, which is imperative for long-read sequencing. The extraction of high-molecular-weight DNA in trees has been limited and difficult to conduct. To achieve successful extraction, modification of the protocol for tree species is necessary. Here, we present a protocol for high-molecular-weight DNA extraction from the broadleaved tree species