Based on recent inbox onslaughts, it seems like there are quite a few questions out there about how exactly to flower your cannabis plant at home, so let’s see if we can clear some things up…
To start, it is important to understand there are two stages to growing a cannabis plant; first, you have the vegetative stage, then you have the flowering stage. The vegetative stage begins once your seedling or clone has put down roots and has more than two or three leaf sets. At this point, your plant should be about a week to 10 days old and should be in a medium to large plant container.
The vegetative stage should last anywhere from two to four weeks, depending on how much space you have and how big you want the final size of your plant to be. As a general rule, your plant will grow two-thirds of its size during veg and another third (to its final size) during flower.
For the vegetative stage, you need to keep your plant under light for a majority of the day, anywhere from 16 to 20 hours of light will do. It is important to give it some dark time during the veg cycle, as this is when the roots do most of their growing. Most growers recommend 18 hours light and six hours of dark per 24-hour day.
Once you have “vegged” your plant for a few weeks and are happy with its progress, it is time to move into flowering. The flower stage will take anywhere from seven to 12 weeks, depending on your strain and environment. Most cannabis strains finish flowering in eight or nine weeks.
To move your plant into the flowering stage, all you need to do is change the time of the light cycle. Whereas you were previously giving the plant 16 to 20 hours of light per day, now you dial that back to 12 hours of light and 12 hours of dark per day. This change in the photoperiod is what unlocks the plant’s internal signals to trigger its flowering stage.
Many people have questions at this point about lighting and watering for plants in the flowering stage. It is most helpful to have a high-intensity discharge (HID) lamp for growing cannabis. Specifically, a high-pressure sodium (HPS) bulb is most often recommended for the flowering stage. But beside the length of light (12 hours) and the type of bulb (HPS), the most important quality of light is its intensity. Weaker lights, such as fluorescent bulbs, which work well for young seedlings and clones in your nursery, are not going to provide enough light energy to bring a cannabis plant all the way through flowering with a decent harvest.
This is the part that scares a lot of people off, but it is really not complicated, just a tad expensive. The cost for a decent HPS lamp is usually around $175 (this includes the HPS bulb, reflector hood and ballast—all of which are necessary). Still, if you use the proper HPS light, you will get that money back (and more) when it comes time for harvest.
Depending on the space of your garden, an HPS lamp that runs between 400- and 1,000-watts is what is needed for a yield that you will be happy with. Many people ask about LED lamps, but these units do not provide enough light energy for good yields and are usually reserved fro supplemental lighting in larger gardens. The guy in the hydro shop will try to tell you otherwise, but that person will be wrong. To be fair, there are some decent LED lamps on the market for flowering, but the price tag on these will be well over $1,000—and those units are not energy (or heat) efficient like the cheaper models.
Plants being driven hard under HID lamps require daily watering and weekly feeding with mild nutrients. Some growers water a couple of times a day and some also feed with a nutrient solution several times a week. It comes down to your preferences, strains and wallet.
As a rule of thumb during the flowering stage, water plants once per day to saturation. When water begins to trickle out the bottom of your container, stop watering. Dissolve nutrients (or use liquid fertilizers with pure water) to create a mild nutrient solution that you feed to plants every third day. Be sure to allow your medium to completely dry out several times a week as this helps aerate the medium and bring oxygen to the roots. In weeks 7 and 8 of the flowering stage, stop using nutrients altogether and use only pure water to flush your plants. The leaves will begin to turn yellow, but this is perfectly normal (due to lack of nitrogen) and will help produce a clean smoke after harvest.
While this all may sound a bit overwhelming, it is not. In fact, it is easy, fun and actually very relaxing. And remember, even if it is trying at times, or a bit pricey here and there, in the end there is nothing like having your own homegrown herb. It is the ultimate reward for a little time and love.
Thanks for reading everyone and remember: Grow… And help the world grow, too!
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Don’t miss the previous Nico’s Nuggets: Temperature & Plants