Article written by
Homegrown Cannabis Co.American Seed Bank and Cultivation Experts
Content reviewed by
Dr. Lewis JasseyMedical Director - Pediatric Medicine
Table of contents
How long does it take to grow weed? The process is complex, and each cannabis plant has a unique life cycle, but on average, the seed-to-yield period for marijuana is three to six months (12-24 weeks).
The precise figure depends on the strain and your growing conditions. For example, sativa plants mature slower than indica ones do. You can generally harvest indoor plants earlier than outdoor crops, and cultivators who train their plants can flip to flowering sooner. If you’re going the home-grown route, here’s a closer look at the cannabis cultivation timeline and tips for influencing it.
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How Long Does It Take to Grow Weed?
While the average cultivation journey is 3-6 months, it can be longer or shorter. Some marijuana gardeners are ready to roll-up eight weeks after buying seeds, while others wait nine months before savoring the fruits of their labor.
Numerous factors affect the sow-to-smoke period, but a major one is whether you plant inside or outside. You sow in spring (around mid-April) with outdoor weed cultivation and harvest before chilly fall nights settle in early October. The whole process takes around six months.
Cannabis cultivation used to be limited to outdoors, but technological advances have enabled growers to garden indoors as well. Tightly-controlled indoor cultivation spaces pay no heed to the weather outside, and growing gadgets allow you to create the perfect climate for your marijuana plants.
This new approach helps cultivators influence how long it takes to grow weed and produce fresh harvests, no matter the month. There’s no hard-and-fast rule on growing indoors or outdoors, but indoor gardeners can enjoy a shorter cycle and flip crops earlier than mother plants would normally permit.
The Life Cycle of Marijuana Plants
Most cannabis plants are photoperiodic, which means they react based on changes in day length. Essentially, plants can “guess” the season by the amount of light they get and adapt growth accordingly.
During the summer, plants stretch and produce flowers as they transition into the reproduction stage. If you’re growing weed indoors, you replicate this pattern with artificial lights to help transition plants through their natural life cycle.
It’s a different story with auto-flowering strains. They have ruderalis genetics and bloom automatically after 5-6 weeks in the vegetative phase. Cannabis ruderalis plants are unique for their ability to survive in harsh climates, meaning you can keep them under the same light cycle for up to 24 hours if you like.
Here’s a look at the four main phases of cannabis growth and the photoperiod requirements for plants grown from seed. If you’re using cloned plants, skip the first two steps. Rooting takes 1-2 weeks, and it’s straight into the vegetative stage from there.
1. Germination (1-10 days)
Germination is step one when growing marijuana. This process employs heat and moisture to trigger hormones beneath seed shells. They respond by producing taproots, which you then sow in a growing medium. The germination stage lasts 1-10 days, depending on your methods. This phase ends when you see the first hints of greenery: the seedling.
2. Seedling (2-3 weeks)
Fragile baby plants are called seedlings and have two rounded cotyledons instead of actual leaves. Seedlings require low-power lights for 18 hours daily and mistings with pH-neutral water; feeding isn’t necessary during the seedling stage.
The seedling stage lasts 2-3 weeks. It concludes when the crop develops leaves with the full number of blades — usually seven. You can now transplant it into a bigger pot for its vegetative development.
3. Vegetative (3-16 weeks)
During this phase, cannabis plants produce leaves and branches that stretch in different directions. This period requires strong light and plenty of nitrogen. It’s also the perfect time to train your plants so they produce more bud sites.
The vegetative stage typically takes 3-16 weeks but can last indefinitely (that’s how mother plants are kept). For outdoor growers, this phase continues until days start shortening after the summer solstice. Indoor cultivators usually stay in this stage for at least a month, as larger plants produce higher yields. Changes in the light schedule are introduced when plants are around three-quarters of the desired final size.
4. Flowering (8-10 weeks)
Whereas the vegetative phase can last as long as you want, flowering is non-negotiable. The plant takes time to display sex, produce buds, and ripen. Harvesting too early will yield crops with weaker flavors and lower potency.
The flowering stage commences when the plant is immersed in uninterrupted darkness for 12 hours each day. Plants will also need heavier phosphorus and potassium feedings. Crops go through a growth spurt before focusing all their available energy on bud production, so avoiding stress is crucial for yield quantity and quality.
For most plants, flowering lasts around 8-10 weeks. Some can take longer to flower (about 12-14 weeks), but exact figures vary depending on the strain.
- Indica cultivars originally developed in harsher climates with short summers and produce buds relatively quickly. For example, some Grape Ape phenotypes can flower in as little as six weeks.
- Sativa strains originated in tropical regions with long, warm summers, so the flowering period tends to be longer. For example, Neville’s Haze may spend up to four months in bloom. Most sativa strains spend 10-12 weeks in the flowering phase.
After flowering, you can start harvesting when buds are ripe enough for consumption. How do you determine the ideal time to collect flowers?
First, look into the specifics of your strain. You should be able to find its expected flowering time online. Figures come in a wide range, but you can help determine the time by what you see in your garden. Use a magnifying glass or a jeweler loupe to examine:
- Pistils: Wispy hairs on buds become rusty and curl inward at perfect ripeness.
- Trichomes: Crystals adorning the flower that should appear opaque or milky-white.
Let the crop sit for a week longer if the pistils are white and the trichomes are still clear. If growing buds for personal use, don’t skip drying and curing. These processes delay smoking for a month, but it’s worth the wait.
Drying takes around a week and makes your marijuana fit for combustion. You’ll then cure buds in a sealed mason jar for two to eight weeks. This process dramatically improves the flavor and smoothness of your final product.
Tips for Growing Indoors
Growing cannabis indoors is highly efficient because all the conditions are under your control. Optimizing the environment allows for greater (and faster) plant development. Here are some tips for how to grow indoors:
- Know your strain’s preferred conditions. Mimic its ideal climate as accurately as possible for healthier crops and stickier flowers.
- Automate climate control. Use timers to turn lights on and off. This eliminates the risk of human error and crop stress.
- Employ correct training techniques. Low-stress training can shorten the vegetative stage and significantly improve harvests. Use the sea of green method for short indicas and the screen of green for lanky sativas.
- Boost growth with gardening hacks. Take advantage of powerful lamps and CO2 supplements while growing cannabis indoors. These tools enable you to get higher output in less time.
Tips for Growing Outdoors
The downside of growing outdoors is fewer elements are under your control, including cultivation duration. But with the right gardening choices, you can make growing marijuana outside straightforward and successful:
- Consider the local climate. Choose shorter-flowering or fast version strains if poor fall weather comes early. Don’t sow moisture-sensitive cultivars in areas that are high in humidity.
- Amend your substrate. Add coco coir or perlite to your garden and supplement it with organic fertilizer. Doing so sets the stage for prolific root development and growth.
- Consider sun and shade. Sow in a spot with at least six hours of uninterrupted sunlight exposure each day.
- Maintain security. Large plants can be attractive to unwanted eyes. Invest in a fence and a locked gate.
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Frequently Asked Questions
Where can I buy cannabis seeds?
Marijuana seeds are available at legal dispensaries and headshops. They can also be purchased online through seed banks. Homegrown Cannabis Co., for example, is a bank where people can purchase cannabis seeds online. The California-based company offers a diverse selection of high-quality seeds and guarantees delivery and germination with every order.
Can I speed up the growing process?
Indoor cultivators with photoperiod seeds can shorten the vegetative stage to speed up the seed-to-harvest period. You can introduce a 12/12 light schedule several weeks after sowing, which results in compact, fast-yielding crops.
If growing outdoors, cover pots with an opaque object or take them into a dark room to get the same effect. Beware of light leaks and stick to a consistent schedule to avoid plant stress.
What supplies do I need?
The tools you need for growing will depend on your setup. Outdoor cultivators require pots, soil, nutrients, and watering and trimming tools. Indoor setups are more extensive and need lamps, fans, humidifiers, and climate meters. Hydroponic growers need even more equipment.
Again, depending on your space and personal preferences, you can add other cannabis growing supplies like pH meters, supplements, carbon filters, and training nets.