Nico’s Nuggets: Flowering Times and Trimming

Hey Nico!
I was wondering if it is OK to trim leaves during flowering? It has been 10 weeks in flower under 12/12 photo-period and fan leaves keep blocking the light. Thanks! – Bianca A.

Hello Bianca. Thanks for reading and writing in!
For starters, 10 weeks in flower is pretty long, unless you are growing a crazy sativa of some sort. Most hybrid strains go 8-9 weeks, some require 10, so be sure to check you trichome colors; if they are beginning to turn amber it may be time to harvest. Using a basic 40x loupe, it is easy to see the color of these resin glands. At the beginning of flower they will be translucent, almost clear. Then they evolve first into a milky white color, before beginning to amber.

As it relates, towards the end of the flower cycle – even as early as week 5 or 6 – many of the bigger, older fan leaves will begin to change color. First they begin to pale and then move from light green into yellow. This is part of the natural progression of the plant’s life cycle and will especially occur as your nutrient regiment tappers off away from heavier nitrogen doses.
Once flushing begins in the last two weeks, many of the leaves will lose their color. It is absolutely OK to trim these leaves off your plant once they begin to pale and yellow – especially the bigger leaves which are older. These leaves are not producing enough energy for the plant to justify hanging around. In fact, they are likely using more energy than they are producing in photosynthesis.

The only caveat here is to make sure you do not remove too many leaves each day. A daily pruning program is always recommended, especially in the last half of the flowering stage. However, only a handful of leaves should be taken each day so as not to stress or shock the plant too much. At this point in its life cycle, the plant will not try to replace those leaves, but rather redirect that energy towards flower and resin production, which is what we want.

Fan leaves near the top that are blocking light should also be removed. Even if they are healthy, large fan leave near the tops of plants often shade too much of the lower branches to make it worth keeping them. Generally though, growth near the top of the plant will be the younger, more productive growth. Striking the right balance is essential, but common sense will dictate where the problem areas are once you are in front of the plant and under your light source.

Thanks for reading everyone and remember: Grow… And help the world grow, too!

Got questions? Email ‘em over to Nico at and be sure to put “Nico’s Nuggets” in the subject line!

1 comment
  1. That’s some good info right there!! I recently just built a flowering room next to a veg room so can do both at the same time. Tomorrow is the end of week one and was wondering about trimming some of the bigger leaves off to let the light come in.
    Thank you again!!

Leave a Reply

Your email address will not be published. Required fields are marked *

Related Posts
Dry Farming
Read More

Dry Farming in Humboldt

A small region along the Eel River in Humboldt County allows cultivators to grow cannabis without ever watering their plants.
Read More

Growing for Terpenes

Increasing terpene production can result in a more flavorful, enjoyable smoke.