Solid questions as usual Soser, and I really don't know how I can convince you that you shouldn't feel bad about asking anything! If I don't know the answer, or don't have time to respond right away, I will let you know, but please don't feel like you are inconveniencing me.
Your first questions is about stock plants getting root bound and the pros/cons of refreshing the plant by taking a cutting. My answer to that is dependent on the cleanliness of your stock plant/cloning operation.
Theoretically a cutting is a true clone. . . but in reality there are a range of things that can occur which will result in the lose of your original genetics during a refresh.
Not all plant diseases display visible signs of infection, and the only way to be sure is to conduct indexing tests that cannabis growers just don't have access to like other plant propagators do. If one of your plants has a virus it becomes of vital importance to eliminate any pests that might vector that virus to other plants and you must also sterilize all your blades/scissors between each plant to avoid mechanically spreading the virus. So the first risk of refreshing your stock plants is that you may proliferate a cryptic virus that may be stunting/slowing growth without you even knowing its there! To be safe, I always alcohol and flame sterilize my scissors between plants when doing any pruning or taking cuttings.
The next thing that you risk when refreshing you mother stock is that you may accidentally clone a branch that has mutated to be slightly different. In the industry this type of single branch mutation is called a 'sport' and is very common especially on certain plants like citrus. Many of our popular citrus varieties today (like cara-caras) are propagated from a 'sport' mutation that they found by luck in an orchard and decided to propagate by cutting! Unfortunately, when you propagate a 'sport' and don't realize you are doing it, you often end up with a lower quality plant from the mutation, rather than a higher quality one. For this reason I always propagate a few branches from each stock plant and do my best to select the most vigorously growing/rooting clone that has as close an appearance to the original as possible.
And then of course, there is the ultimate risk that something may go wrong in your propagation area and the clones may die after you have killed the original stock, or you may mix up labels and end up losing track of what clone is what!
Now that I have covered all the cons. . . how bout a couple pros?
Stock plants that are given ample root environment (as big as you can give them ideally) will grow more vigorously, produce tighter noded, better cuttings that root faster! The increased vigor will benefit you in controlling pests and disease also because a healthier growing plant is more resistant to problems! If space for pots is an issue, refreshing your stock can create this same environment in a smaller pot when starting with a smaller new clone.
Commercial industry propagators also have the ability in today's high-tech tissue culture facilities to propagate the microscopic cells that make up the plants apical meristem, which actually outgrows any plant viruses and when the tissue culture plant is mature it is virus free even when taken from an infected plant!
Now, with all that said, I keep my stock plants in extremely small pots (1 cup - 3/4 gallon) and only do a refresh about once a year! Like you, I have plenty of genetics in my stable that I just dont have the space to grow as frequently as I would like to, so to reduce vigor and time spent by me pruning them back, I choose to keep them root bound until a few months before I want to grow that strain. When I plan on growing cuttings from a stock plant I will either transplant into a larger pot, or refresh the clone and put it back into a 3/4 gallon pot.
Ok, that answer probably rambled on longer than it needed to. . . onto question #2
The reason some growers cut larger fan leaves in half when taking cuttings (I don't) is because the plant loses water through the leaves and takes water in through the roots. . . so when you cut off the root system, you ideally want to reduce the water lose from the leaves as much as possible! This is why we keep the cuttings lightly misted and in a high humidity environment. Reducing the surface area of the leaf blade will also help reduce transpiration water lose, but is wounding the plant and exposing it to opportunistic disease that will thrive in warm moist areas (cloning chamber) like rhizopus. Depending on the size of the leaves on the plant you are cloning, cutting leaf blades in half may be a good idea, but if you keep your stock plants under T5 the leaves will rarely be large enough to warrant cutting. It would be a better idea to maintain even light misting at all times during the first week of rooting than worry about cutting leaves. I clone under a humidome, so water lose is never my issue, but high heat and the diseases that come with that are, so I don't cut my leaves.
Next question about skirting plants for increased growth:
Removing parts of the plant that are sinks and increasing the ratio of sources:sinks remaining is always going to increase the growth rate for the remaining tissue. If the lowest leaves on your plant are past their prime maturity and starting to decline in photosynthetic efficiency or are becoming excess salt storage tissues then removing them will be removing sinks (a sink is a tissue that requires more energy to grow than it is currently producing). When I thin my lower canopy in the first couple weeks of flowering, I do not remove lower leaves. I remove just the bud that is growing at the node where the leaf petiole meets the stem. Getting the experience to know how high up you should remove buds before your yield will start going down in the end is tough. I have had grows where I definitely removed buds too high, and some were I left way to many on and got a ton of larf. . . the trade off isn't going to be 1 to 1 with removing lower larf and getting more top quality bud, but if you do it right it should be close. It may be tough to tell, but from the base of my plants to the top of my colas is never even 3 feet, so removing lower leaves is not nearly as much of a concern for me as it would be for someone growing 4 or 5 foot tall trees that get no light penetration that low in their canopy. If disease has never been an issue for you then you may be growing in too low a humidity. . . because the ideal environment for plant growth is sadly the ideal environment for disease growth many times also! Pruning a thick canopy of lower leaves is very helpful in increasing air flow enough to prevent the growth of disease.
I hope I didn't go too off track with this long post, let me know if I missed answering anything for you Soser!
-Meeks
