The biggest variability in how long a marijuana plant takes to grow will happen in the vegetative stage—after the seedling phase and before flowering.
When your marijuana plant becomes a seedling, you’ll notice it developing more of the traditional cannabis fan leaves. As a sprout, the seed will initially produce leaves with only one ridged blade. Once new growth develops, the leaves will develop more blades (3, 5, 7, etc.). A mature cannabis plant will have between 5 or 7 blades per leaf, but some plants may have more.
How long does it take to grow a marijuana plant?
Seed germination length: 3-10 days
Be sure to keep a grow journal to track the progress of your plants. Looking back on your notes will help you learn from mistakes and maximize the quality and quantity of your buds.
There are a number of changes to consider once plants go from the vegetative stage to the flowering stage:
Now that harvesting and trimming are complete, it’s time to cure your flowers. Curing is an essential process that removes the last of the residual water from the buds, minimising the chance of mould and greatly prolonging shelf life. Curing also enhances the taste and quality of the smoke, making for a smooth and potent experience.
For more info on drying and curing your herb, check our blogs Top Tips To Successfully Dry And Cure Your Fresh Cannabis Buds and How to Cure Your Cannabis Buds.
Aside from the buds themselves, another way you can tell your plant is approaching harvest is by examining the colour of the leaves. Provided you haven’t overfed your plants during the final stage of flowering, a yellowing of the leaves will signal that your plant is reaching peak maturity, and that its nutrients are being fully utilised by the buds. By flushing out nutrient salt buildup with pH-balanced water for a couple weeks before harvest, a smoother, more pleasant smoke is guaranteed from each plant.
Photoperiod strains are induced to bloom by the hours of light they receive; indoors the grower changes to a 12-12 light-dark cycle to artificially promote flower growth.
Ultimately, the most important use for your magnifying glass is to detect the progress of your trichomes, and therefore, the proper time to harvest your buds. Trichomes are small mushroom-shaped glands that produce resin which contains the vast majority of cannabinoids and terpenes.
Photoperiod strains can be kept in vegetative growth indefinitely so long as 18+ hours of light and suitable conditions prevail. This is what allows indoor growers to keep mother plants for years and why outdoor grower’s plant in springtime. Indoors or outdoors 18+ hours of light facilitates taking cuttings too.
Outdoors Mother Nature dictates the grower’s schedule and flowering will only commence in Summer/Autumn as the hours of daylight naturally diminish, making for a longer more gradual flowering period. Weed growers in the Northern hemisphere don’t refer to October as “Croptober” for nothing.
With the stretching of cannabis in early flowering, you may possibly want to think about training techniques such as low stress training (LST). This is where you bend the stems down and away from the centre of the plant so you can get an even canopy for a more efficient use of your grow lights. This can help you obtain much better yields later on.
To find out when it’s time to harvest your plant, you can use a jeweller’s loupe or a small microscope to regularly check your plants’ trichomes. You can observe whether the trichomes turn from clear to a milky white colour. If many of the trichomes you see are still clear and transparent, it means it’s still too early for harvest. But when most of the trichomes have an amber colour and an opaque clarity, this means that the THC content of the buds is at its maximum and the plant is ready for harvest.
Bud rot is a serious issue that can ruin an entire harvest. To protect your plants and optimise their growth, keep the relative humidity of your grow room at 45%.
Flowering cannabis plants like daytime temperatures of 20–23°C and nighttime temperatures of around 15–18°C. Make sure to watch out for sudden drops or spikes in temperature when you turn your lights on/off. Sudden drops can shock your plants, while sudden rises can cause condensation to form on the surfaces of your buds, leading to bud rot.