Thinning is the action of manipulating plant height and numbers either via cutting the plant at the stem or removing plants from the grow altogether. Naturally plants compete for light and plants that grow taller than the rest can easily prevent light from reaching other plants in the group. This is especially noticeable with unstable strains and new hybrids in which some of the population may grow more vigorously than others. The action of thinning your crop either by cutting or total removal creates a more even canopy and allows light to penetrate every top cola without some plants getting in the way of the other plants' light requirements.
Thinning generally applies to outdoor growers, but some indoor setups such as ScrOG and SOG may also need to be thinned.
As a cannabis grower you should aim to produce plants of relatively uniform growth. When all of your plants are approximately the same height, you can more easily achieve optimal lighting conditions. If one plant grows more vigorously than the others, you risk ending up with light gaps. For instance:
• Distance from Plant A to light is 3 feet
• Distance from Plant B to light is 1.5 feet
• Distance from Plant C to light is 8 inches
Obviously you will be wasting light, not to mention space, on this setup. The reason for uneven growth is simply that some plants tend to be more vigorous than others.* If this happens, the more vigorous plants will cause the smaller ones to receive less light. We use a process called thinning to control these vigorous plants.
Clones, taken from the same mother, should not need to be thinned because they will all possess the same genetic makeup.The only time that clones will not grow in a uniform manner is if light dispersal is uneven. Obviously the clones that receive more light have a better rate of photosynthesis and will grow more vigorously. If all the clones are treated in the same way, they should grow uniformly.
If you discover a vigorous plant, either cut it down to the same level as the others or remove it from the grow altogether. Do not throw away the cuttings from thinning. You can clone these cuttings into new plants!
You may be tempted to thin the other way round, leaving the taller plants and removing the smaller ones. Recall that in cannabis growing, if you have started from seed, the taller plants are generally male and the smaller ones are female. For this reason do not give in to the temptation of removing plants before you actually identify their sex.
Thinning your grow makes it look nicer, tidier and helps to improve your overall yield by preventing potentially good plants from being covered by weaker ones that are growing much taller. Remember that height and size have nothing to do with potency. Some plants with very long internodes tend to grow very tall, covering other plants and diverting most of their energy into vertical growth rather than bud production. This kind of competitive growth will only lead to less than optimal results.
By the time you have finished your thinning you should have a uniform with some clones that you can use to grow more bud.
GROWING - LIGHT BENDING
Light bending occurs when a plant grows at an angle toward the light. You may have noticed plants on the perimeter of your grow area bending toward the light to try and get their share. If your plants bend too much they will eventually grow toward or even into another plant and block other plants from the light. Also, during flowering the buds will become heavy and may cause plants to fall over.
A simple way to avoid light bending in an indoor grow environment, is to simply switch your plants around. If a plant leans too much in one direction, then move it toward the middle of the grow space or turn the plant around. It only takes a day or two for the plant to straighten. If your plants can't be easily moved, as is the case with hydroponic setups and outdoor gardens, then you may have to tie your plants so they don't bend.
If you are growing outdoors and have a major problem with light bending you may have to cut away surrounding foliage to allow more light to reach your plants. If this is not possible, try using thread and small stakes, such as bamboo, to keep your plants upright. Remember: if your plants are bending they are trying to tell you that they need more direct light.
PRUNING FOR YIELD
Pruning is the action of manipulating the number of node regions (potential bud sites) that your plant creates and has nothing to do with the thinning process. Cutting a plant at the stem will automatically result in Hopping'. For this reason, plants that are thinned via cutting will end up growing more than one top cola. Topping is discussed in the next section. This section covers pruning to increase yield.
By using stakes you can also control and separate branch growth after pruning.
This plant has generated more than eight new node regions after pruning.
Prune cuts are made using clippers held at a 45-degree angle to tbe shoot being cut. For every stem or branch that you prune, the cut area will develop two more branches.This process is natural: just look at any tree to see how the stem divides into branches which sub-bivide into more branches which divide into new shoots and leaves. Marijuana plants grow branches out from the stem. Any filling out occurs when new leaves and branches develop at the node regions. Some of these branches may develop new shoots, but these are somewhat smaller and thinner and don't support as much bud growth. If you prune your plant you can make it more like the example of the tree.
Recall that Indica plants tend to be smaller than Sativas. If you learn to prune your plant properly you can produce small bushy Sativa plants that grow in tiny spaces. Without pruning, a Sativa plant can stretch to five feet or more.
Keep in mind that there is a limit to how much you can prune a marijuana plant. If you prune the stem, it will split in two. You can prune both of these new stems and end up with four stems. You can try to prune each of these four stems to create eight stems, but results will depend on the strain and its genetically predetermined branching limit. You might be able to prune some of the lateral branches, but again, if the plant has reached its threshold it will not produce more branches. All strains are different in this respect.
Some marijuana growers will take a pair of clippers to the top of their plant just above the last branch formation during the third or fourth week of vegetative growth. The top is removed by shearing it away at the stem. What happens next is that the main stem splits off in two or more directions, creating a V-shape at the top of your plant. The end result after flowering is two or more top colas instead of one. Now, two top colas instead of one does sound appealing and some growers have even managed to force a plant to grow more than six top colas using this method. Unfortunately this topping method of pruning doesn't always lead to better results.
Depending on the strain and the growing environment, the 'topped' plant may produce two small top colas instead of two big ones. Also, each strain has a threshold for bud production that cannot be improved upon because it is a genetically predetermined factor. On the other hand, some plants when fully grown without topping do not reach their threshold. The strain Blueberry is a good example of this. If you grow Blueberry without topping you won't achieve maximum bud production from that plant, but if you top the Blueberry, you will. Other strains aren't so flexible and the two top colas will simply share the same volume of bud that a single cola would have produced on the same strain.
It's advised that you keep in mind that pruning for yield using the topping method is strain-dependent and experiment carefully with this pruning method. Do this with 2 out of 10 plants in every grow. You'll find in time that during this vegetative prune you will be able to shape your plant. Plants are generally pruned three to four weeks into their vegetative cycle, but can be pruned sooner or later or more than once.
Pruning during flowering is not advised as the plant will be forced to divert its energy from bud production into branch and leaf production. This results in a slower rate of bud growth. For optimal growth finish your pruning well before flowering.
There is a topping method known as the FIM technique. If you push the leaves apart at the very top of the plant you should see a small bud (not flowering bud but an actually leaf bud). Use a pair of nail clippers to pinch off about 3/4 of the bud. This should result in more than two top colas being developed. In a single FIM clipping you can produce up to eight new top colas.
The origins of this technique are humorous. As the story goes, FIM was discovered accidentally when a grower messed up a topping exercise. FIM stands for: "Fuck I Missed".
HOW TO MAKE CANNABIS BUSHES
Some people prefer their plants small and wide. Fortunately for them, making cannabis bushes is a simple process. During the third week of vegetative growth prune half the plant's branches. Cannabis plants need at least 50 percent of their leaves in order to continue growing without experiencing fatal stunting problems. If you prune off more than 50 percent of their leaves, you may end up killing your plants.* Do not prune only one side of the plant; prune both sides to achieve the 50 percent. You may also prune the main top cola if you want to split it into two or more parts.
If the prune cuts you previously made grow new branches and leaves, you may wait until the fourth or fifth week of vegetative growth and prune again, leaving 50 percent growth.
During the seventh week of vegetative growth you'll notice that your plant has started to grow outward more than upward. Let's say you have a plant with eight shoots. That means it is four nodes high. You prune the plant and end up with 16 shoots, but the plant is still only four nodes high. Now this does not mean that you can keep doubling shoots forever. Pruning merely pushes the plant to grow all of its shoots early. If you keep pruning a plant that is four nodes high until the eighth week of vegetative growth, the greatest number of shoots you will get will be about 32. Most marijuana plants will not grow much beyond this factor, but again this is strain-dependent.
Now each new shoot has a junction point or a node that it grew from and each node should produce bud during the flowering stages. It is possible to create a marijuana plant that droops over the sides, completely concealing its own pot. With the right strain, it is also possible to have a single plant spread over an entire 6x6 foot space using this method. Creating cannabis bushes usually requires a few additional weeks of vegetative growth.
REVERTING TO VEGETATIVE GROWTH
This is also called Re-veging, regeneration or rejuvenation and can be done anywhere between the start of flowering and the end of the plant's peak bloom when it is ready for harvest. This does not work with strains that have autoflowering properties like Ruderalis.
The first thing you need to do in order to revert a plant back to vegetative growth is to quit the flowering photoperiod of 12/12 and change this to a vegetative pho-toperiod of 24/0 or 18/6. The 24/0 photoperiod is certainly better because it reverts your plant to vegetative growth quicker.
The next thing you should do is to remove all of the plant's flowers and calyx development by clipping them away from the plant at their base. When your plant is bare of its flowers and calyx development you can then choose to reduce the height of your plant to a stage where it resembled its vegetative growth. After a few weeks your plant will revert to vegetative growth and will no longer flower until the 12/12 photoperiod is initiated again.
When you are satisfied that your plant has reached a satisfactory level of node production change the photoperiod to 12/12 and your plant will flower again.
Reverting to vegetative growth is a way to harvest more flowers from the same plant again, however it does have the following disadvantages:
• Reverting to vegetative growth can take up to four weeks to occur properly. This time could have been spent by simply cloning the original plant and growing these clones out instead. Cloning is usually much quicker than rejuvenation.
• Plants that are rejuvenated tend to not produce the same quantities of bud that they did during their peak bloom although it is not impossible for them to do so.
• The growing medium will contain higher levels of P than l\l and K.This needs to be changed to higher or equal amounts of l\l to P and K. This can be hard to do without flushing your soil or performing a transplant. Both of these can cause stress which may lead to sexual dysfunctions appearing in the flowering stage a rejuvenated plant.
• Rejuvenated plants go through a certain amount of stress because of the photoperiod change and this can induce sexual dysfunction.
• Stress from cutting the plant during regeneration may also induce sexual dysfunction.
Some other grow books have suggested that rejuvenation compromises the genetic integrity of the plant. This is false.
A good example is if you take an IBL strain which is stable for all of its traits and pollinate the females with a male from the same strain you will produce a batch of offspring. Keep some of the male pollen used in this exercise and rejuvenate one of the females. After you rejuvenate her use the male pollen again on her to create another batch of offspring.*
If rejuvenation compromises the genetic integrity of the plant then these two sets of offspring will show variations. Do the normal offspring exhibit variations when evaluated against the rejuvenated female's offspring? No, they do not. Thus rejuvenation does not compromise the genetic integrity of the plant.**
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Posted March 11 2006 - 08:57 PM
Great spirits have always encountered violent opposition from mediocre minds-Albert Einstein
The greatest service rendered any country is to add a useful plant to its culture-Thomas Jefferson
The greatest service rendered any country is to add a useful plant to its culture-Thomas Jefferson