Speaking of defoliation, I've had that question on my mind. I've been told that removing leaves and branches that don't get any light:
1. reduces humidity from transpiration
2. increases air flow to prevent mildew
3. saves work trimming larfy lower buds later on
4. puts more energy into building big cola(s)
I'm especially curious about #4: does trimming lowers really build bigger tops? I've been getting bolder about trimming lowers, but I don't have any science to back it up.
Looooonnnng reply..
I think that if you ask some people they will tell you that "in nature" plants don't get defoliated. I mean, they do. But not the way that we might do it, or as thoroughly (OCD?). But I always question the nature statement, because in "nature" they aren't under "perfect" lights, in tents in the best environment possible (in our situations), fed the "best" food. Not to mention hydro. So...why draw the line at defoliation?
On the other hand, when it comes to something like a tomato, my Grandad who taught me a lot about gardening always said, grow tomatoes, not leaves. Prune those suckers off and watch the N.
And my own little analogy would be: If you were to install solar panels in your house, would you install panels in your basement where they get no light? Same applies (IMHO) to plant.
When I see HUGE fan leaves, with REALLY long stems, that tells me that the plant is pushing that leaf out to gather light and that is a waste of energy for the plant. Especially on a leaf way at the bottom of a plant that will lead to basically zero production. I would prefer the plant to push that energy to it's tops.
Anyway, I'm having a little fun because I'm fried. But you get a lot of different answers. Certainly good for air flow. And beneficial for humidity to an extent.
What I do notice is that when I cull the smaller buds and foliage from the bottom of the plant, and the interior of the plant, in a heavy veg, I get bigger tops/ fruits. I think that a given plant will direct it's energy to put out as many fruits as it can to survive (cause it thinks it's gonna breed with a male and produce seeds). But it's a limited resource in what it can actually put out. You can have 1000 tops that are smaller. Or, by removing the little stuff, it puts the resources that would be directed into those tiny buds into the bigger ones. When you remove things, it tells the plant to take that energy and put it into the productive areas to ensure it will reproduce = bigger buds = more chances to catch pollen. That's one of the reasons that I try not to train for so many tops. You will likely get the same yield with more tops/buds/fruits, just spread over a wider area. If that makes sense.
Also, when the plant has stopped stretching, unless you have an endless space to really open everything up, stuff at the bottom isn't getting much light. That's why it gets all stretchy and airy down there.
IMHO, YMMV, Hot debated topic sometimes, and all of that jazzz.