I've tried both over the years, and what I've noticed is when you strip all the fan leaves away, you remove a lot of the plant's stored energy (in the form of starches, as well as mobile nutrients), as well as all the chloroplasts in those leaves that conduct photosynthesis.
You think of all the energy the plant has used to build those structures, as well as all the energy that is stored in them, and you have just taken that away.
After all, what is the first thing you notice about a stripped plant after you remove all it's fan leaves? The plant straight away starts to rebuild, replacing fan leaves, enlarging those that were not removed, and diverting energy into this process that could be used to build root structures, main stems, branches and new growth. You have basically stunted the plant.
Now let's have a think about the reasons for lollipopping (stripping fan leaves). It is to let light into the undergrowth, correct? Good. But after you remove all those leaves to allow light into the undergrowth, what part of the plant is it that actually uses that light? If you said "all the leaves you have just removed", you would be mostly correct.
Cannabis flowers do contain chloroplasts, so they do photosynthesise. But they are not as efficient at converting electro-magnetic energy (light) into stored energy (starches) and transportable energy (sugars) as leaves.
So that's what I mean by a "false economy" - you have allowed more light in, but you have removed the very structures that most efficiently use that light.
Similar to roots, leaves capture, store and supply energy to other parts of the plant. The less distance travelled, the more efficiently energy and nutrient can be transported. The more light, the more energy can be converted. The larger the leaf volume, the more energy can be stored.
Plants are not stupid. If there is no light, they have two choices. Just like with growing roots, they can "search" (expend energy stretching for light, like a root stretches for nutrient and moisture), or they can let that part of the plant expend its remaining energy and die, while the plant concentrates on transporting nutrient to and from other parts of the plant that have adequate light.
The plant does whatever is more efficient.
Where there is light, there is growth. Where there is no light, growth will stretch and/or eventually die off.
So what does this long post mean? It means there are more efficient ways to provide light to plants than removing all their stored energy and chloroplasts.
If you "lollipop" a plant and then put it straight into flower, you will temporarily stunt it and the plant will use valuable energy to grow new fan leaves and restore lost starches and mobile nutrients instead of expanding its structure to increase flowering sites.
If you "lollipop" a plant and then allow it to grow back in veg before putting it into flower, what have you achieved? Nothing. You've just temporarily stunted the plant and you still end up with lots of leaves anyway!
OK, so I know "lollipping" can also mean removing underdeveloped branches and growth at the bottom of the plant to turn it into a "lollipop" where most of the branches are an even height to maximise the canopy. This would be preferable, and you can also remove fan leaves at branch junctions to "stunt" (or rather slow) individual branches to allow other branches to catch up. This usually means removing some of the top fan leaves on newer branches that are higher to allow lower branches to stretch and catch up.
In terms of light and plant efficiency, an even-height canopy makes the best use of a concentration of light at that point. Filling in that canopy is the most important thing. Having enough leaf and root mass to support growth is also important. You can remove leaves and allow light to penetrate, but that light will be weaker than the light above at canopy height.
So is it better to allow weaker light to penetrate further into a canopy that has lots of holes it it (multiple layers of bud sites at different heights), or to fill in the canopy to maximise the best concentration of light at a certain height by having an even layer or "carpet" of buds?
In my opinion, it is the latter.
Many years ago, when I started growing with vertical HPS lights, there was always a debate about turning the plants on a regular basis so that the "dark" side of the plant could get more light. I tried both ways and came to the conclusion that there was no need to turn plants - because the plant would simply grow on the light side and divert all its energy into areas where there was most light. Vertical growing is like turning your canopy sideways.
This is the result. You will see that the canopies of these plants are not very thick at all! The most important thing is that all the buds are near the light and that there are no gaps (there was a gap created in the photo below to show the position of the light - otherwise it was completely surrounded by plants).
Think of your horizontal canopy like this vertical canop. And I did not strip fan leaves from any of these plants!
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