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How Long Does It Take? Growing Marijuana Indoors

growing marijuana indoors
September 07, 2020

There are lots of things that can affect the length of an indoor grow. Your lights, your plants, your choice of nutrients, etc… the more you understand these elements both individually and collectively, the more you’ll be able to influence the speed of your grow.

Growing Cannabis Indoors: Factors Affecting Growing Speed

So how long will an indoor grow take? And how can I speed things up? Your average indoor grow will take three to five months, with some grows lasting closer to seven months. To go from an average time to a more detailed estimate, however, we’ll need to assess the individual elements of YOUR grow.


As the ‘nature vs nurture’ debate suggests, both genes and environment determine the development of living things. For cannabis plants, the genes of the individual strain largely determine the growing speed.

Indica strains tend to flower faster than sativa, and ruderalis strains can produce buds within weeks of germination. Don’t forget: good quality seeds are vital. There is no point worrying about growing speed if your cannabis seeds don’t even germinate.


In the absence of natural sunlight, artificial lighting systems provide plants with the energy needed for photosynthesis. The rate of growth depends on this process which, in turn, depends on the type and intensity of the light source.

Optimized lighting can significantly boost growth. A plant that receives too little or too much light will become stressed, focusing energy on survival instead of bud production and growth. Be sure to follow the breeder’s guides and always observe your plant for signs of stress. You can check our Beginner’s Guide, Choosing Your Lights Episode for further information.


Cannabis plants thrive in temperatures between 70 – 85°F (20 – 30°C) during the vegetative phase and 65 – 80°F (18 – 26°C) during flowering. Temperatures outside these ranges will slow growth and can lead to a host of other problems. Ventilation, humidity and air conditioning are major things to consider, as is the distance between the lights and the plants.


Nitrogen, phosphorous and potassium are essential nutrients for plant growth. Additional macronutrients like calcium, magnesium, and sulfur also play a vital role throughout the life cycle of cannabis. Providing these nutrients in adequate amounts significantly boosts growing speed and overall foliage development, as well as terpene and cannabinoid production. If the plants don’t get the nutrients they need in the correct amounts, plant growth WILL be compromised.

Grow Media

Soil is the obvious choice for outdoor growing, but there is a range of options open to the indoor grower.

One of these options is hydroponics, a growing medium that can shorten the growing period by up to three weeks. In a hydroponic setup, the roots of the cannabis plants are submerged in nutrient-rich water where they directly receive the nourishment they need for growth. Rather than constantly searching for nutrients, the plant can focus more energy on bud and foliage growth.

Stress Induction

While stress can aid growth to some extent, excessive amounts can significantly inhibit the growth and development of an organism – be it a plant or animal.

In cannabis cultivation, plants are intentionally subjected to mild stress training such as topping or FIMing, to encourage healthier growth. These techniques must be employed with caution, however, as excess stress can inhibit growth and lengthen the cycle.

How Long Before Seeds Become Smokable Buds?

Growing cannabis from seeds takes an average of three to five months, from planning and preparation, nurturing the growing plant, to harvesting and curing your cannabis.

Task Duration
Preparation 0 to 4 weeks
Growing from Seed to Buds 12 to ~31 weeks
1. Germination 1 to 5 days
2. Seedling Phase 1 to 4 weeks
3. Vegetative Phase 3 weeks plus (a photoperiod plant can remain in the vegging phase almost indefinitely)
3. a. Sativa At least 3 weeks
3. b. Indica At least 3 weeks
3. c. Ruderalis 2 to 3 weeks
4. Pre-flowering Phase 2 to 3 weeks
5. Flowering Phase 7 weeks to 16 weeks (4 months)
5. a. Sativa 10 to 16 weeks
5. b. Indica 7 to 12 weeks
5. c. Ruderalis 3 to 4 weeks
Post-Harvest 3+ weeks
1. Drying 7 to 14 days (2 weeks)
2. Curing 1 to 4+ weeks
Jar method Up to 6 months
Water Curing 5 to 7 days
TOTAL At least 15 weeks.

Cannabis Growth Cycle

Strain Duration
Sativa ~27 weeks (~6 to 7 months)
Indica ~23 weeks (~5 to 6 months)
Ruderalis <12 weeks (<3 months)


Creating optimal indoor growing conditions for cannabis plants requires planning, preparation and probably a few trips to the shops.

Purchasing the Equipment

Depending on the location, supplier, and desired setup, buying your equipment can take up to fourteen days or even four weeks when delivery time is factored in. The bigger the grow, the bigger the kit. A hydroponic set-up, for example, will require bulky aerators, opaque tanks and a piping system etc. There is your lighting rig and air-con to consider, too. Be wary of lengthy online delivery times and don’t pop your seeds until you’re ready. Take a look at our “Buying Your Stuff” chapter with Kyle Kushman to know more about your marijuana growing kit.

Choosing the Seeds/Clones

Try to order your seeds at the same time you order the equipment. Unlike clones, seeds can be stored with minimum hassle: a dark, cool cupboard or drawer will suffice. Ordering from a seed bank within the country can take anywhere from two to ten days. Seeds sourced overseas can take up to four weeks to arrive.

Tip: If you choose clones, make sure you have everything ready before they arrive as you’ll need to keep them alive! It takes a slightly different approach to be able to grow plants from clones, so we do recommend starting out with seeds.

Choosing your seeds can be daunting, so you need to understand the three main types: sativa, indica and ruderalis.

Sativa. Sativa weed strains are lanky plants that reach up to five meters tall. They’re characterized by slender leaves, long branches and clustering flowers. The finished height of sativa strains means indoor grows could be a challenge, but a sativa will reward the grower with bigger yields. They spend little time in the vegetative phase (~ three weeks) but longer periods in the flowering stage (ten to sixteen weeks).

Indica. Your typical indica strain grows shorter than sativa. Once fully developed, it won’t reach more than two meters tall. They are known for their bushy stature, narrowly-spaced branches and broad, rounded leaves. Indica is generally preferred by indoor cultivators because of the manageable stature and shorter flowering time of seven to nine weeks.

Ruderalis. Ruderalis is the smallest and fastest growing of the three cannabis species. It also produces the least amount of resinous bud. Autoflowering strains are a popular choice with indoor growers, often finishing their entire cycle within three months of germination, regardless of the season. This equates to three, sometimes four harvests per year.

Growing Stages

The cannabis life cycle is relatively straightforward with only three main stages: germination, vegetative and flowering.

Growing weed indoors allows control over parameters that affect growth such as light, nutrients, and ventilation. The length of time spent in each stage also varies based on the flowering period of the strain and the lighting schedule.

1. Germination

Cannabis seeds will take between twelve hours and five days to germinate, depending on the viability of the seeds and the method of germination used. Some seeds can germinate within a day; others take as long as three to five days. Healthy seeds will be dark in color with stripes or mottling on the shell. Check our step-by-step “Germination Guide” for further information.

2. Seedling

Seedlings will take between one and four weeks to become strong enough for transplant. Good, viable seeds naturally shed husks faster and grow the first set of leaves earlier. The better the quality of seeds, the shorter the seedling phase will be. Using clones instead of seeds allows the grower to skip the germination and seedling stage altogether, but the mature plant will be weaker and, in most cases, the yield will be twenty to thirty percent smaller than a seed-grown plant.

3. Vegetative

The vegetative phase is the period at which the plants bulk out and gain mass.. On average, this takes at least three weeks and could last even up to six months, depending on the genetics of the seedling and the preferred light schedule of the cultivator.

Auto-flowering. Despite their short life span, autos still spend considerable time in the vegetative stage. Auto-flowering varieties require a minimum of two weeks before transitioning to the flowering phase.

Photoperiod. Photoperiod strains have a longer vegetative stage. It takes at least three weeks for the plants to mature. However, some opt to extend this period by up to six months.

Growth rate leading to the pre-flowering stage will also vary based on the strain and growing methods. For instance, sativa plants spend less time in the vegetative stage than indica. Plants grown in a hydroponic system also tend to develop faster than those planted in soil.

4. Pre-Flowering

Weed enters the pre-flowering stage once the cultivator shifts the photoperiod to twelve hours of consecutive light followed by twelve hours of consecutive darkness.. This period lasts for two to three weeks.

Auto-flowering. These plants bloom two to three weeks after germination regardless of the light schedule. The pre-flowering stage for autos is characterized by the appearance of buds with white pistils.

Photoperiod. Photoperiod strains pre-flower roughly eight to ten weeks after germination.

5. Flowering

On average, the flowering stage lasts for five to twelve weeks, depending on the strain. White pistils will gradually turn orange as the plant nears full maturity.

Auto-flowering. The flowering stage for autos occurs within five to seven days. Harvest will occur within weeks of the appearance of the first white pistils. These plants do not hang about.

Photoperiod. Photoperiod strains spend seven to twelve weeks in flower and go through three sub-stages (early bloom, mid-bloom, and late-bloom). Approximately four to six weeks after pre-flowering, the pistils will start to turn pink or orange. It is only in the seventh to twelfth week that the majority of the pistils will turn dark-orange or brown, an indication that the buds are ripe enough for harvest. An indica will mostly spend seven to twelve weeks in this phase whereas your sativa could take as long as ten to sixteen weeks.


Harvested buds should take seven to ten days to dry ahead of the cure. This stage plays a pivotal role in defining the potency and the overall flavor and aroma of the buds. The process must not be rushed or cut short.

Plants should be cut and hung whole in a dark room with a temperature range of 68 to 70°F, humidity at 50 – 60%. One way to test if the buds are ready for curing is the snap test. Try breaking the stem of the buds. If it appears brittle and snaps off crisply, it’s dry enough for the cure.


The period for curing varies substantially depending on the cultivator’s preference and technique used. It could take up to six months, but it’s a step that should neither be skipped nor expedited as curing can be the difference between average and exceptional bud.

Jar Method

To cure cannabis using this method, place the dried buds in a sealed mason jar and open once or twice daily to release moisture. If the buds stick together, open the jar for longer periods – at least twelve hours for further drying. Reduce the frequency of opening as time progresses. The buds can be cured in the mason jar for up to six months. After that, it must be vacuum-sealed to preserve the taste and smell.

Water Curing

Water curing needs less time to complete, taking five to seven days to rid the buds of nutrient residues using this method. The smoke will be smoother, but some terpenes may be lost to the process. You need to decide whether this is a worthwhile trade-off.

Reaping the Buds of Labor

Nobody could take a seed and tell you exactly how long it will take before you can turn it into harvest-ready buds. There are too many factors at play. All we can do is make educated guesses based on the variables we have discussed above. Generally speaking, an autoflowering cycle will complete in three months, with a photoperiod averaging at three to five months. Genetics, environmental conditions and personal preferences in growing techniques will all play their part.

Despite the ambiguities, one thing is certain: cultivating and procuring marijuana requires a lot of time and effort. Come harvest time, once the air is filled with the fragrance of your dense, aromatic buds, all that effort will be worth it.

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