Optimizing Marijuana Flowering

Updated: Dec 30, 2018

Flowering cannabis is the most exciting phase for most gardeners. There is nothing more exciting than watching months of work come together in such a beautiful way - not to mention we are that much closer to harvest!


The first step of transitioning a plant from vegetative growth to flowering is to determine the length of flowering cycle for each strain - now is the time to date our labeled plants. Uncle Pete prefers to put the date of harvest on each plant immediately when it goes into the flowering room.


Optimize Vegetative Growth First

The most common mistakes which compromise flowering are made before our plants ever get here. It is quite common for new gardeners to spend all of their time, energy, and money on flowering while neglecting the vegetative cycle. Once our flowering rooms are set up and the environment is properly controlled, the yield of the harvest is determined by the plants we put in. Don't make the mistake of skimping on vegetative growth and then expect a miracle in the flowering room. Every day of the plants' life leading up to flowering will play a role in the outcome. The more experience the gardener has with a specific variety, the easier it is to manipulate plants into the size and structure we want in the flowering plant. Generally speaking, the gardener wants to grow bushes with multiple tops. The more bud sites and tighter the node spacing the better. Additional detail may be found in the basic topic Optimizing Vegetative Growth.


Setting Up The Flowering Room

Light and Space

Assuming the gardener has invested time wisely during the vegetative growth cycle, there are some nice bushes heading into the flowering room. We grow our plants in either 10 or 20 gallon containers as discussed in the basic topic Optimizing Vegetative Growth. In a 10 gallon container, we expect to yield 14-16 ounces of dry flower depending on variety. In a 20 gallon container, we expect to yield 20-30 ounces of dry flower. These yields are reached under 1200 watt double-ended HID lights with 10 foot ceilings. Uncle Pete’s flowering room is 12x24 and holds an average of 20 plants, covered with 10 lights. The entire grow including vegetative growth room and work area is housed inside a 24x24 garage.


During the initial period of flowering - before the plant begins to bud - cannabis plants will "stretch" for 2-3 weeks. This means that not only do they continue to grow new branches, but also lengthen their stems between branches. Some varieties can double or triple their height during this period. Make sure you have enough vertical space under the lights for the varieties you are growing. Experience is the best teacher for making the most of the space you have in your garden without exceeding it.