For me it depends on the structure of the plant. Something like cfl...'s, you've got to do something with it or else it's going to yield less and mold (if the climate is humid) like crazy. Clones tend to bush out quite a bit more than seedlings and I usually only grow seedlings so I prune less than almost everybody else. My opinion changes from year to year, the last couple times I've had busy plants like that I had to prune a lot. They molded like crazy anyway and all the pruning wounds rotted so I've been more cautious about what I do.
On Instagram I've seen people that remove everything, every leaf and branch, from the bottom half of their plant. I find it aesthetically displeasing and the plant turns out as nothing special or impressive. The tops don't blow up huge. They're indoor growers, growing outdoors. They get a half oz or a oz a plant of nice little nugs and they're happy, I guess. It's different then lollipopping or training or pruning or anything else. So I try to dissuade people from it, but we're all different growers and do things our own way.
I know an old guy, lives off in the mountains in a cabin, he doesn't touch his plants. He has one weird thing he does, he'll tie his plants over on the ground. But that's it. He doesn't even remove the dead leaves. It's bone dry out there so he can do that. (and it bugs me) But he never prunes or leafs, grows huge plants and gets big yields. If that's scratch, the starting point, what can I do from there to improve things? And a lot of the stuff I try doesn't do as well as he does. So I keep going back to scratch and working from there.
One thing I don't do much of anymore is leafing. It's mostly the older leaves lower in the plant earlier in the year. I've found it doesn't make that big of a difference either way. You can strip half the leaves off, or not, and the plant is still going to do what it does. One thing I do different than everybody else. Once the plants get to early mid-flower I leave them alone. I wait until the leaves are almost dead before I pull them off. Almost everyone else pulls the leaves the moment they start to fade.
In Marijuana Botany Robert Connell Clarke says the plants are mining the leaves for nutrients in flowering, stripping the N,P, and K out of them to push the flowering. I don't think the plant wastes nutrients keeping them alive, I think it's the opposite. The leaves supply nutrients for flowering. Only we don't notice it because we're feeding our plants so much. The leaf produces sugar for the plant, and it gives the nutrients it used to create the leaf back. So stripping doesn't make sense, unless you're letting light penetrate into it. But if it's just penetrating into the stalk what's it doing?
I've noticed in wet weather the canopy provides protection from the wind and rain. Keeps the inside of the plant and the ground underneath the plant dry. The plants on the outside of my 'wall of plants' and the flowers at the tips are more mold prone than the stuff that's protected further down the branch. A reason why the biggest flowers at the top always get waterlogged and rot.
We talk a lot about 'air circulation', what we really mean is a plant that's overly bushy with a soaked interior. The light doesn't penetrate so the interior isn't able to dry out. I think the air circulates fine because you're outside. The humidity, the wind, is what it is. It's that the plant takes too long to dry out because the growth is so thick. This is different than the outer canopy I'm talking about that keeps the plant's interior dry. I don't mind a thick outer canopy but I want an open interior.
I believe the leaves dry the plant, the buds, out faster, through transpiration, than if it was fully leafed. As soon as the rain stops and the sun hits it the plant has to pull water from somewhere to keep the leaves from wilting. It's going to come from either the ground or the soggy flowers. If you haven't been watering and the inside of your plant is dry it's going to have to pull water from the outer wet areas to maintain it's moisture balance.
I've always grown in the PNW, basically in a rain forest, so I think and experiment a lot with this stuff over the years. A plant in an open field by itself will always get soaked and rot much faster than plants in a group lined up against a wall of trees and vegetation. If the wind break is to the N/NE/NW. You want the south to be open for full sun.
Also, references from American literature might not apply to European countries. Those white butterflies likethe one in the picture, usually lay their eggs on jasmyn plants, and decimate them.
