Mainlining help, when to top a second time?

If you want to mainline you need to top them aorund the 3 or 4th note and let them grow out. then top both of them again equally on each side while keeping the new growth pinned down to the ground via LST. Other things to note is stripping out the extra growth between your first node you topped to the medium and the next 4-6 node after that first node so they have some distance between the two apex growth sites. Think of it like a highway to two different cities, they need room to expand and turn into the metropolitan bud sites they can be. If they are two close they clash and space becomes to tight. The whole purpose is to create two main paints off of one root system. If one side of the plant is large or has more apex growth sites it will be larger in the end and may take away from the other side. they need to maintain the same height for the first bit as growth hormones in plant go to the tallest bits. In my blue cindy diary I did something like mainlining with a SCROG and it turned out really well. lots of topping and made a kick ass canopy. Not 100% mainlining but close. Good Luck!