MrJonesanswered grow question 4 years ago To me depends on your plants, and your growth plan, trellis are used to support and guide growth, for photoperiods, I tend to allow plants to get close to the height I am looking for before I plip them, -lean and prune lower growth, leaving about 2 to 3 nodes, then placing the trellis right at canopy level, flip to flower, and guide colas as they stretch,.