I get asked this question a lot - "How much will I yield from one cannabis plant?" This is a really common question and there are two groups asking it - beginner growers and people who don't grow but are considering growing. Unfortunately, predicting the yield from one plant is impossible. Nobody can predict a yield based on the per plant basis. In an indoor grow, there are ways to calculate a good yield such as using the, "gram per watt formula." But with that method, you are calculating yield based on the potential of your lighting - not by the number of plants. So if you are growing four plants in a 4'x4' grow tent for example, the gram per watt calculation would include all four plants - not just one. The gram per watt method is however a more accurate method for indoor growing than the other methods out there.
For outdoor plants, yield cannot be calculated accurately there either. The yield on an outdoor plant can be anything from an ounce to a couple of pounds. The big contributors to the final harvest weight are weather conditions, how long your plants spend in the vegetation stage, and whether they are Indica or Sativa dominant. A strongly Sativa dominant plant grown in an ideal outdoor environment can be described as a tree - and it yields like a tree too! Nutrients are also a factor and can have a big impact on your final yield. It's true that experienced growers can combine all of the variables in their head and create a ballpark figure for the yield they expect. Although, it's not an exact science and there's certainly no average yield per plant. Some may say it can be estimated by strain but there are still too many variables to accurately predict.
Most people who ask the yield per plant question are really asking a similar question which is easier to answer - "How much do I need to grow to supply myself personally?" I'll give an indoor and an outdoors answer to that one. When growing indoors, regardless of your growing medium or your type of grow system, a single 600-watt high intensity discharge (HID) grow light can grow everything that the individual needs - even if that individual is a heavy smoker. I am assuming of course that the person is growing competently. For outdoor grow operations where lights aren’t an issue and plants can be tall and large, you will not need to grow more than a couple of plants at a time for personal use. Again, this is assuming a certain level of competence. To sum things up, it's not possible to accurately estimate how much one cannabis plant will yield. There are just way too many variables.
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