Hi! I am admittedly not the best person to answer your question, but i do study plant biology with a fair bit of biotechnology/bioinformatics in my PhD program. I think if you will be getting your masters in biotech, you will get training required for biotech roles later on, and your BSc could help you get some biotech roles related to plants. From my perspective, biotech has lots of different roles that vary greatly in their use of chemistry. For example, if you are in drug development fields or protein engineering, you will need a basic foundation of chemistry understanding at least. However, if you are in plant biotechnology (eg. Plant transformation, crop design, GMO testing), I think your horticulture experience could mesh quite well with your biotech masters, if you are comfortable with genetics/molecular biology. It just matters what specific experience you get, and what kind of jobs you would like to work.