Bioinformaticians execute frequent, complex, manual and semi-scripted workflows to process data. There are many tools to manage and conduct these workflows, but there is no domain-specific way to textually and diagrammatically document them. Consequently, we create methods for modeling bioinformatics workflows. Specifically, we extend the Unified Modeling Language (UML) Activity Diagram to the bioinformatics domain by including domain-specific concepts and notations. Additionally, a template was created to document the same concepts in a text format. A design science methodology was followed, where four iterations with seven domain experts tailored the artefacts, extending concepts and improving usability, terminology, and notations. The UML extension received a positive evaluation from bioinformaticians. However, the written template was rejected due to the amount of text and complexity.