What is the Best Lighting Cycle for an Autoflower?

One of the most highly debated topics in all the cannabis industry is, what is the best lighting cycle for my autoflowering cannabis? After almost a decade of exclusively growing autoflowers, we can say a few things on this. In this article, we will discuss the importance of measuring your PPFD (photosynthetic photon flux density) or PAR (photosynthetic active radiation). This may sound like a scary term, but we assure you they are not scary at all. In fact, they are quite fun!

Understanding PPFD and PAR

Below is a basic guide to where your optimal range for PPFD should be based on where they are in the growth cycle. Now, a lot of folks are asking, what is PPFD, or how do I find out my PPFD? There are several apps for most smartphones that will let you get a reading of what your PPFD is. With a quick google search you can find one that you feel is best for your phone. These may not be super accurate, but it will give you an idea of where you are PPFD-wise. That will be enough for most people to succeed and get some familiarity with PPFD.

Natural Light Cycles for Autos

First, I would like to refer to mother nature here. Ruderalis (also known as autos) that grow in the northernmost parts of our planet have adapted to a very long light cycle during its growing season. Generally, this is going to be more than 18 hours per day of direct light, with a decreasing amount of light for the remainder of the day. The theory is that these plants never get a total dark period in nature. Now, they don’t get full sunlight for those 24 hours, but it never goes completely dark.

We don’t always use nature as a direct example of what to do. For example, it hales in nature, but we don’t want to go and pelt our indoor plants with ice periodically, right? When it comes to lighting and autos, though, we can take a very good clue.

Rest Periods for Autos

As an evolutionary response to a very rapidly changing light cycle, these plants can carry out all their biological processes in low light conditions versus a completely dark period. When this topic comes up, most people say (correctly) that all plants need rest. And this is totally true: the difference with autos is that they can rest and do all the things needed during that rest in low light vs. complete darkness.

Optimal Lighting Cycle

Enough with the sciencey stuff! We here at MVB believe that the optimum lighting cycle is 24 hours of light. 18 of those hours should be full intensity, and the remaining hours should be lower intensity.

Here is an example:

  1. 18 hours of 100% intensity
  2. 2 hours of 50% intensity
  3. 2 hours of 20% intensity
  4. 2 hours of 10% intensity

This is just an example; you can give them less or more during the “rest period.” This is where learning specific cultivars becomes beneficial. The main thing to remember when it comes to what lighting cycle is best for your autos is that anything more than 18 hours will be sufficient.

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These plants have evolved to grow very fast in a short period of time. By maximizing inputs like light, nutrients, temperature, humidity etc. you will maximize the genetic potential of these amazing plants. Autoflowers love to grow. If you give them the right things, they will love you back! As always, make sure to check out all the top autoflower breeders at Multiverse.

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