4: Repeat Step 3 until you have the desired number of colas (keep topping plants until you have 8, 16, or 32 mains)
As Nugbuckets mentioned, each time you top the plant, it doubles the total number of colas. This is because you're essentially splitting a main cola in two with every topping.
So you top a plant once for 2 main colas, top a second time for 4 mains, top a third time for 8 mains, etc.
This chart should help you figure out how many times you want to top your plant in total, and how many colas will be produced. There's more information below the chart about why.
Growing Indoors: Top 3 times for 8 colas
As a general rule, when growing indoors under grow lights it's best to have 8 total nodes. This means you will top the plant a total of 3 times, including the first time.
Growing Outdoors or in Greenhouse: Top 3-4 or more times for 8-16+ colas
When growing outdoors it's best to have 8-16 total nodes or more to take advantage of the light of the sun and allow your plants to grow into huge bushy monsters. This means you will top the plant a total of 3-4+ times.
Growing Scrog Style: Top 5 times for 32 colas
When growing using the
Scrog technique, I prefer to produce 32 total nodes to get the most out of each plant under the Scrog net. This means you will top the plant a total of 5 times.
I only use the Scrog technique when growing a Sativa dominant strain (as these tend to make lots more secondary branching and "fill out" more than Indica-dominant straains). I always allow the plant to have some time to stretch and really fill out under the net before I initiate flowering.
What does main-lining look like with a ScrOG setup?
Picture Example - Marijuana plant topped for 8 final mains
Before - 4 mains
Before - Side view
After
Same plant after being pruned for 8 mains (and secured to the sides of the pot)
Just a few days later, her 8 new mains are already pointed up and facing the sun