average yield for a single northern light plant?

depends on several factors, how big is the plant (how many nodes, branches)
what nutes, training or topping excercises... if you want to increase natural yeild, read this. i recomend lst. simplest, easiest, low stress, low mess.

"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.

TOPPING
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.

FIM Technique
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".

Super Cropping Technique
Another method of topping is called xSuper Cropping'. By taking a branch between your forefinger and thumb you can gently crush the branch, causing it to develop multiple branches above the crushed area. You must crush it on the correct side or risk breaking the branch. Just squeeze lightly until you feel the branch give, then let go. If it gives easily then you have crushed it on the correct side. If it is hard to crush and the branch splits then you have chosen the wrong side. Practice makes perfect with Super Cropping.

Super Cropping should be carried out during the second or third week of vegetative growth and does stunt the plant. You should also note that plants that are Super Cropped can remain in the vegetative growth stage for twice as long as normal but the end result is a very bushy plant with multiple node regions that should all produce bud. Many growers have thrown Super Cropped plants away because they believed that the plants were not flowering in time. If you Super Crop your plants make sure that you have the patience to wait until the process is finished which — usually about four to six more weeks of vegetative growth.

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.

TRAINING
Training was covered in Chapter 8 in our discussion about advanced SOG and ScrOG setups. Training simply means tying down your plant's main stem so that it grows in an S-shaped pattern. You can also train your plants to bend into other shapes but the S-shape is the most common. Training is mainly used to prevent plants from reaching their natural vertical height without pruning, although you can also prune trained plants without a problem.

Training does not stop your plants from growing to their natural height but instead promotes horizontal instead of vertical growth. You can also prune trained plants if you want but most growers just rely on the training to achieving optimal results. Training is accomplished by bending the plant over, attaching a piece of thread to the stem and securing the thread to either another part of the stem or another plant or object. By tightening the thread bit-by-bit, day-by-day, you can successfully bend your plants without causing them undo stress.

Fishing line works very well in cannabis plant training. Some of the threading may be located very close to your lighting and heat can cause some threads to snap or even burn. Fishing line works best because it is one of the most durable and heat-resistant filaments you can buy. Make sure not to tie your line too tightly around the stem or you could end up cutting into it and causing plant stress, topping it or even killing it. People have managed to grow plants of all sorts of shapes using this method — from corkscrews to full circles. Some growers even like to grow their plants horizontally during the vegetative growth stage with just a single 90-degree bend at the base of the plant. When done correctly with the right strain, training can lead to excellent overall bud production.*
If a stem breaks during training, simply hold it in place using a stake/stick and bind it with cheesecloth or a porous cloth bandage wrap.There are many types of plant waxes that you can buy from gardening stores to help close the wound. If you do not have a wax, applying honey to the wound also helps. Honey has healing properties that help rejuvenate plant wounds but must be carefully examined every day for fungi development on the honey-treated area. If you do find fungi development simply refer to Chapter 12 on how to solve this problem. Watch for any new growth at the break area and trim these away, because they will try to break away the upper part of the stem, effectively topping your plant. It is not uncommon to find roots trying to grow out from a damaged area although the high percentage of air outside of the break zone will prevent the roots from growing much more."

forgot where this came from, but don't give me credit. it is not my work.

hope this helps,

love, brooke