Mainlining

Mainlining begins by topping the plant above the third node when it has developed five to six nodes. All growth below the third node is removed, leaving only the two branches at node three. When those branches develop a few nodes, they are topped again, creating four branches. The process can be repeated once more to create eight main branches, which is the most common mainline structure. Throughout the process, all growth is kept symmetrical, with each side of the plant mirroring the other.

Mainlined plants produce remarkably uniform harvests because every cola receives equal energy and light. This consistency can be valuable for commercial growers who need predictable bud sizes and quality. The technique also creates an open canopy with excellent airflow, reducing mold risk. The downside is that mainlining extends the vegetative period by two to three weeks compared to untopped plants, due to the recovery time after each topping. It is best suited for photoperiod strains where the extended veg time is manageable and not recommended for autoflowers.