Isn't cannabis a weed? Why is it so hard to grow?

The term 'weed' isn't scientific; it's just a designation for plants that people find a nuisance. The cannabis plant we all love is definitely not a nuisance! There is truth in that cannabis grows just fine without human intervention in many geographies. In almost all cases though, marijuana needs specific care to optimize yield and potency.

The cannabis strains we grow did not evolve naturally, without human intervention. Calling some of the modern strains natural would be like to calling a chihuahua a natural wolf strain. Just like dogs, we have evolved these plants to our needs. In the case of cannabis, we have selectively bred for improved potency, reduced flowering time, bigger yields as well as pest and drought resistance. The result is a plant that optimized to produce large, potent flowers but requires relatively specific environments. The guides on this site are designed to help you understand the cannabis plant and how to grow beautiful, kind and productive marijuana plants.

To grow top-shelf cannabis, there are ten essential topics you'll need to learn about.

  1. Grow Space - Where are you going to grow?
  2. Lights - If your growing indoors, what kind of light will you use?
  3. Containers and soil - What are you going to grow in?
  4. Seeds and clones - What strain will you grow?
  5. Water and nutrients - How will you feed them?
  6. Germination - How do you germinate cannabis?
  7. Seedling care - How do you care for seedlings?
  8. Vegetative care - How do you care for vegging cannabis?
  9. Flower care - How do you care for cannabis in flower?
  10. Harvest & curing - When and how do you harvest?

Before diving in on these topics, let's address the two most pressing questions on every new growers mind: how long will this take and what will I get for it?

How long does it take from seed to harvest?

In almost all cases, it takes at least three months from the time you start to germinate the seed until the plant is ready to harvest.

Germination: Germination begins when you first put the seed into a damp medium and ends when the seed first emerges. Germination takes between 3 and seven days.

Seedling: Begins as the seedling emerges and lasts until the plant starts growing 5 and seven-point leaves, usually in 2 to 3 weeks.

Vegetative: During the vegetative phase, the plant puts all of its energy into increasing mass. Vegetative stages last until the plant is switched to over 12 hours of uninterrupted darkness each night. Outside, this happens naturally in the fall, but indoor growers choose how long the days last.

Flowering: Flowering starts after the plant is kept in total darkness for over 12 hours per night. This is where the cannabis will grow buds. The amount of time spent flowering depends on the strain, but it generally takes between 7 and nine weeks until they're ready to harvest.

You will also need to dry and cure your cannabis, which takes at least 3 to 4 weeks.

Learn more about marijuana plant's stages and get a broad overview of caring for cannabis at each phase in our cannabis lifecycle guide.

Vegging your plant for 1 to 2 months will drastically improve yields.

How much will one plant grow?

Yield depends on a lot of factors. Cannabis under bigger lights grow bigger buds. Some strains have higher yields than other strains. Synthetic nutrients often produce larger yields than organic nutrients. Topping and training both improve yield. Many complex factors impact yield; so much so that this entire site is dedicated to helping you understand the intricacies so that you can maximize yield and quality.

This most significant impact you can have on your yield is also the simplest: grow bigger plants. Since indoor farmers can choose when to put plants into flower, the veg cycle can be as short or as long as they want. Putting seedlings into flower is the fastest way to get bud, but generally produces only 20-30 grams per plant. Leaving the plant in the vegetative state for a month will more than double that. Add another month, and you can double that.

Where should I grow?

This is one of the first decision you'll need to make since the of the rest of the choices hinge on where you're growing.

There are many options for where to grow and your choice will mostly depend on your needs and what's practical. You can get creative with where you grow, as long as it has good airflow and enough room for stretching cannabis plants. You will want to consider stealth, available space, how much you want to grow and other factors to make your decision. Since photoperiod flowering plants are so sensitive that even single flashlight sweeping by can be enough to stop flowering, light control is essential. For auto-flowering strains, it's less critical.

Outside - Cannabis is often grown outside and is an excellent option if available to you.

Space Bucket - These are self-contained environment-in-a-bucket are perfect for single plant stealth grows.

Grow Box - They are an excellent option for small and stealthy grows for a single plant production. You can pick these up premade or make your own or repurpose an old piece of furniture.

Closet - A spare closet can make an ideal grow space because they offer proper height and are good at keeping light contained. You will need a fan for ventilation in most closets.

Grow Tent - Grow tents range in size, from 2' x 2' (.6m x .6m) on up and are great options for all phases on cannabis life. Tents have great ventilation, reflective walls to make efficient use of lighting and they keep light contained to keep your grow stealthy.

Farmers often use multiple methods through the plants lifecycle. For instance, you might veg in a space bucket, but move to a grow tent for flower, or veg in the sunlight and finish off in a closet.

To learn more about grow spaces, head over to our grow space guide.

Girl Scout Crack flowering under LED lights

What kind of lights should I use?

Once again, there's no shortage of options and the best decision for you depends on many factors. You'll want to consider heat control and balance cost to purchase and cost to operate when you make your selection.

Natural sunlight is a great option if available - it's free and renewable. Sunlight through a window results in low yields, so you will need to live in an area where its safe to have the plant outside during the day. You can augment sunlight with artificial light sources.
Fluorescent - Compact Fluorescent Lights (CFL) and fluorescent tube lights can be great options for your plants. The upside is that they're cheap, burn relatively cool and are readily available - you most likely have some in your home right now. The downside is that since they don't transfer as much power to the plants as LEDs, they can burn hotter.
LEDs - In recent years, LEDs have overtaken almost all other lighting types for home grows. They are relatively inexpensive to purchase and operate and burn very cool compared to traditional grow lights. In virtually all cases, we recommend LED lighting to other sources.
High-Pressure Sodium lights are incredibly effective lights and have been successfully used to grow amazing buds for decades. They do burn hotter than LEDs, which can cause temperature problems in tents and other confined spaces.

This Raspberry Cough (bred by Nirvana Seeds) is flowering under LED lights.

Often, farmers use multiple sources. You might keep seedlings on a windowsill during the day and move under fluorescents in the evening. Learn all about lighting options and schedules in our lighting guide.

How long should I leave the lights on?

There are a couple of things to consider on lighting schedules. To keep photoperiod strains from entering flowering, vegging plants need more than 12 hours a day. Light cycles are generally denoted as light/dark hours. Standard options are 18/6 (18 hours of light followed by 6 hours of dark), 20/4 (20 hours of light followed by 4 hours of dark) and even 24 hours of light without any darkness. The best way to keep your plants on a reasonable schedule is to pick up a timer. These are inexpensive and readily available online or at local hardware or department store.

Learn all about lighting options, automatic controllers and schedules in our lighting guide.

What kind of container should I use?

Just like with everything, there are lots of options available for containers and the best type for you will depend on some factors. The primary requirement is that it must drain excess water well since cannabis plants don't like to sit in water.

Trade Pots - Trade pots are the kinds of containers that plants are in when purchased from commercial nurseries. Typically black or dark green hard plastic, these basic round or square pots come in a variety of sizes from 2.5 ounces (0.07 Liters) to 20 gallons (~76 Liters).

Solo Cups - Solo cups are a brand of plastic cup that happens to work very well during the seedling phase. They are a hard plastic cup that comes in a variety of sizes from 3 ounces (0.08 liters) to 16 ounces (~ .5 liters). Drainage holes aren't typical features on drinking cups, so you'll need to add those yourself.

Plastic Grow Bags - Plastic grow bags are exactly what they sound like: plastic bags made for growing. They come in a variety of sizes, from 1 quart (~1 liter) up to 5 gallons. They are made from soft plastic in black or white (to help with reflection. They have excellent drainage, but the best part is that you can quickly cut them off the plant to simplify transplanting.

Fabric Grow Pots - Cloth or fabric grow bags, also known as Smart Pots, are precisely what they sound like cloth, bags made for growing. They come in a variety of sizes, from 1 quart (~1 liter) up to 50+ gallons. They are made from soft fabric that is easily air and water permeable. They have excellent drainage, but the best part is that even overgrown plants won’t become rootbound due to 'air-shearing'. Air shearing is the process where roots shear off when they reach the air spaces at the edges of the bag, preventing them from becoming bound as they search for new soil.

Shopping Bags - Working on the same principles as cloth grow bags, many cloth shopping bags can be repurposed as grow bags! These bags drain water very well, are easy to transplant out of and are durable enough to be reused multiple times.

Regardless of what type of container you choose, most farmers report better results when they start seedlings in small pots and then transplant to larger containers as the plant grows. Keeping plants in appropriate sized containers helps prevent overwatering and any resulting root issues. Learn about different container options and how to transplant in this guide..

What kind of soil or medium should I use?

Cannabis can survive in many types of soil, but it has some requirements to thrive and develop healthy root systems capable of delivering water and nutrients all the way up to the growing buds. To grow kinder bud, you have to start with a growing medium that will let your plant mainline water and nutrients. The right medium meets these requirements:

  1. Drains excess water well, but doesn’t dry out too quickly.
  2. Light and airy enough - compacted soil will stunt root growth.
  3. Maintains pH balance, and efficiently delivers nutrients.

Most commercial potting soils don't meet these requirements out of the bag and will need to be amended with coco coir and additional perlite to lighten the soil and improve drainage even more. Here are standard options for meeting these requirements:

Commercial Blends
There are commercial blends available that contain mixtures of soil, coco coir and perlite that are specially formulated for marijuana. This is an excellent option if possible.
Make Your Own
Start with a high-quality pH balanced potting soil and add coco coir and perlite. It's a little more work, but a less expensive option and can be tuned to suit your grow.
Hydroponics merely is growing without soil, by exposing the roots to nutrient solutions in water. The roots can be free floating in the water or supported by an inert medium, like coco coir, perlite or rice husks. Most farmers use air-bubblers to oxygenate the water to allow for rapid uptake. Hydroponics is an advanced farming technique but can result in faster growth and larger buds than growing in soil.

To meet all of these requirements, we make our mix that starts with commercial potting soil; then we add coco-coir and perlite to improve drainage, nutrient delivery, and water retention. Learn to make your own or learn more about pre-mix options with our soil mix guide.

This Sweet Love (bred by Philosopher Seeds) has a high CBD content and is excellent for medical use.

What strain should I grow? Where do I get seeds?

Now that you have everything you need to grow cannabis, you need to get something to grow. You can start with seeds and germinate them, or you can get a clone - which is just a cutting from a female plant that has sprouted roots.

There are lots of strain available, and the right one will depend on some factors. If you are space constricted, you will want to select a compact strain. If you grow area doesn't have good light control, you will want to choose an auto-flower strain.

In many areas (like the UK and Spain in Europe or Oregon and California in the US) seeds and clones can be purchased from shops, dispensaries or directly from the breeder. In other areas, you will need to order them from an online seedbank - check your local laws.

For a deep dive into selecting the right strain for you, check out our seeds clones and strains guide.

How do I germinate cannabis seeds?

Cannabis seeds are easy to germinate as long as they are kept moist and warm. Pot seeds don't require light to germinate, but the young seedlings need light as soon as they emerge. You can germinate them in a damp paper towel, directly in soil or in a peat plug. The time required to germinate varies by method and strain, but we consistently get results in 1 to 4 days using the peat plug technique described in our germination guide.

How do I care for seedlings?

The seedling phase begins when the young plant first emerges from the seed and extends for the first few weeks of life. Seedlings are born with a pair of small round leaves, called embryonic cotyledons, that were formed in the seed. The young seedling uses these leaves to bootstrap photosynthesis and growth processes. In the next days, it will begin developing its first true leaves. See our Cannabis Lifecycle Guide for an overview of all phases of marijuana's life.

The primary objective of the seedling phase it to allow the plant to develop hearty leaves for photosynthesis, healthy roots to slurp water and nutrients, and a sturdy stem to support the plant. It's best to let the seedling do its job with minimal interference from the grower.

For details on caring for seedlings, visit our seedling care guide.

How do I care for vegging plants?

The vegetative phase begins when the young cannabis plant starts producing five and seven point leaves. At this point, the young plant will need to start consuming large quantities of water, light, and other nutrients, as they enter this stage of rapid growth. See our Cannabis Lifecycle Guide for an overview of all phases of marijuana's life.

The primary objective during the vegetative phase is to create as many bud sites and as much plant mass as possible while training the plant into the final growth shape before flowering begins. We do this through training, topping and selective pruning. To learn more about topping cannabis plants, see our topping guide. Most farmer's combine topping with training and pruning to multiply yields by optimizing the plant's shape to their grow condition. Check out our step by step guide on low-stress training to learn how to do this in your garden.

Cannabis plants in the vegetative stage are incredibly robust and quickly regenerate from injuries, pests, and nutrient deficiencies. To learn more about caring for vegetating cannabis plants, see our vegetating care guide.

How do I care for flowering plants?

The flowering phase is where the plant produces sex organs. Females will produce the flowers we know as buds. Males will produce pollen sacs, in bunches that look like grapes. See our Cannabis Lifecycle Guide for an overview of all phases of marijuana's life.

During the flowering phase, the stems will become woody and rigid. Flowering plants do not recover from pests, deficiencies, and other accidents quickly, so you treat your plants with care while they are flowering. To learn more about caring for flowering plants, see our flowering care guide.

When should I harvest?

The amount of time spent in flowering varies by strain, but generally, your buds will be ready to harvest 8-10 weeks after flowering starts. There are two simple methods for determining when your cannabis plants are ready for harvest that will optimize potency, and give the best-finished product overall.

Most Precise: After a percentage of trichomes have turned milky or cloudy
Simplest: After a portion of pistils have darkened in color.

Visit our harvesting guide for more details on when to harvest.

How do I dry and cure?

To dry the plant, hang it up. You can hang the entire plant or cut off individual branches. You will remove and manicure the individual buds from the branches after they are dried.

Keep the relative humidity between 30% & 60% and the temperature between 65F & 80F (18C & 26C). Avoid too much airflow to keep the plant from drying too fast. In general, you want to take between 3 and seven days to dry your buds.

The curing phase is when your cannabis will improve its flavor profile and increase potency over a series of natural processes. During this time, you want to keep a stable humidity between 50% and 60% with reduced airflow. We do this by putting the manicured buds into quart-sized Mason jars along with a bi-directional moisture control at 62%

Visit our harvesting guide for more details on drying and curing.

Why should I top or FIM cannabis plants?

If left to grow naturally, marijuana plants produce only one main cola - topping improves yield since branching causes the plant to produce multiple large colas. Each cola won't be as large as the single cola would have been, but then the overall yield will be more significant.

Where do I cut the top?

Count up five nodes and cut the growth tip just above the 5th node, like in the illustration below.

Cut about 1/4 inch (0.6 cm) above the 5th node

To learn more about Topping and FIM'ing with step by step instructions and diagrams, visit our topping guide.