When to start counting the days of the cannabis flowering period

When to start counting the days of the cannabis flowering period
Luke Sholl

Harvesting your plants at the right time is crucial. Unfortunately, many growers incorrectly calculate the flowering time of their plants and end up harvesting premature bud.

This is a mistake we see growers make all the time. They start counting their flowering days too early and eventually end up with a premature harvest. The reason? Many growers—even those with plenty of experience—forget that their plants go through a “pre-flowering phase.”


The pre-flowering phase is an important part of your plant’s life cycle. It starts when the light conditions around your plants change and the days become shorter. In a grow room, this is usually when you switch your light cycle down from 18/6 to 12/12. In nature, this happens naturally at the end of summer.

Cannabis plants undergo a variety of changes when they enter this phase. Pre-flowering plants stop focusing on vegetative growth and instead get ready to reproduce. This is also the time you’ll start noticing the gender of your plants; female plants will start developing calyxes and hair-like pistils, while males will grow round pollen sacs.

The pre-flowering phase can last anywhere between 1–3 weeks—depending on genetics and the environment you’re growing in.


Many growers start counting the days of the flowering cycle when they bring their lights down to 12/12. However, the plants haven’t actually started flowering at this time. Instead, they are just entering the pre-flowering phase.

You should start counting your flowering days from the day you see the first pistils emerge on your plants. Again, this can vary from plant to plant, so you should check on them daily once you initiate the change in light cycle. The minute you see a pistil, you can start counting down the days to harvest.


Remember: any flowering information you get from a breeder should be taken with a grain of salt. Flowering times always vary, and you should never harvest your plants after 58 days just because the breeder said so. Always make sure to closely look at your plant's buds and check their trichomes with a magnifying glass to ensure you harvest at the right time.

Luke Sholl
Luke Sholl

Fascinated by the wellness potential of nature, Luke has spent over a decade writing about cannabis and its vast selection of cannabinoids. Creating, researching and writing content for Cannaconnection, alongside several other industry-related publications, he uses strong technical SEO skills and diligent research to bring evidence-based material to thousands of unique visitors.