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Vegetative stage

A Beginner’s Guide To The Cannabis Vegetative Stage

The cannabis vegetative stage is essential to the yield and quality of your final crop. Many new growers underestimate the importance of this stage, and the internet is full of conflicting information. We understand the heartbreak many growers experience as a result of poor plant performance during this phase.

In the cannabis vegetative stage, your plants build the foundations they need for flowering. They’re stacking up the nutrients and vigor they’ll need to flourish with many healthy colas later. So how you nurture them right now will impact how much cannabis you harvest later. 

This easy guide will explain what the cannabis vegetative stage is, when it starts, how long it lasts, the common pitfalls to avoid, and more. 

Join us as we give you everything you need to grow healthy cannabis plants. 

Weed vegetative stage
Weed vegetative stage

What is the cannabis vegetative stage?

The cannabis vegetative stage is the period between the seedling and flowering phases. This period is where the cannabis plant experiences its “growth spurt”. 

As it increases in biomass, this it the ideal time to start trimming and training the branches for optimal growth. Ensure that light is evenly distributed throughout the plant, encouraging an abundant yield.

Much like a growing child, your cannabis plant needs more nutrients to grow strong and healthy. Pay close attention to signs of deficiencies and take action immediately. You can’t go wrong with nitrogen-rich soil at this stage.

Like a young sapling, the plant requires water closer to the stem as it builds strength. During the vegetative stage, you should focus on supplying water further from the stem—accomodating its expanding roots.

If you want to avoid pollination, this is the time to monitor your plants closely as they’ll develop reproductive organs within the first few weeks. As soon as you spot those pollen sacks, rip the plants out.

When does the vegetative stage start for cannabis?

Under optimal conditions, you could expect your plant to enter its vegetative state between three and six weeks. The exact time frame depends on the strain you choose. 

The first complete set of fan leaves indicate the beginning of this busy period

During the vegetative stage, you’ll see your cannabis plant developing more stems and leaves, rapidly becoming fuller. The plant’s main focus now it to grow big and strong—ensure that you provide the best possible conditions (temperature, humidity, water, nutrients, soil) to help it thrive. 

Your cannabis plant develops distinguishable greenery compared to its initial foliage. Monitor your plant carefully to identity any signs or infections, pests, or deficiencies. Be ready to act immediately as this could put your whole crop at risk.

Early veg stage
Early veg stage

How long does a cannabis plant vegetative stage last?

The cannabis vegetative stage can last anywhere from 3 to 16 weeks depending on the specific strain you’re growing, how big and tall you want your marijuana plants, and whether you’re cultivating your vegetative stage cannabis indoors or outdoors. 

However, how long it takes to grow cannabis overall will have to take into account the seedling and flowering stages also. So check that info when you order your seeds

Vegetative stage indoors

Indoors, you control how long the vegetative cannabis stage lasts by managing the light photoperiod. Anything over 12 hours of light per day is excellent. 

Vegging indoors commonly lasts six to eight weeks for most cannabis growers. However, those who prefer to keep their weed plants small sometimes veg for as little as four weeks. 

Vegging in such short timeframes is only achievable because some veg stage cannabis plants can flower after only four weeks. Farmers reduce the number of daylight hours below 12 hours to trigger this.

Vegetative stage outdoors

Outdoors you have no control over the amount of light your cannabis receives. Thus, the cannabis vegetative stage will last for however long sunshine is available. Veg will only give way to the flowering stage when the amount of natural sunlight per day starts to drop.  

Growing requirements for vegetative stage cannabis

There are six special provisions you should make for vegging cannabis plants to help them grow to their full potential. Checking off these boxes ensures your crops will have a successful veg stage and a high rate of flowering later. 


Ideally, vegetative stage cannabis thrives under an 18/6 lighting cycle, which means 18 hours of light to 6 hours of darkness. This is a popular schedule you’ll see in many cannabis farming projects. 

However, 24/0 is also popular if you’d like to grow your weed plants into massive monsters. It’s going to reflect on your energy bill at the end of the month, though.

After years of experience, growers who know what their specific cannabis cultivars respond to will sometimes opt for 17/7 or 19/5 lighting schedules because they find this produces the biggest yield.

Cannabis in the vegetative stage under LED lights
Cannabis in the vegetative stage under LED lights


Keep vegetative stage temperatures between 68°F and 77°F if you want to have a healthy crop. 

When temps run too cold, cannabis plants are unable to absorb key vegetative stage cannabis nutrients. This can stunt your weed crops’ growth. Conversely, when temperatures run too hot during veg, there could be heat stress on your cannabis


Your room shouldn’t be too damp or too dry during veg. Such extremes may shock your weed plants and create conditions conducive to cannabis crop diseases and yield-lowering heat stress.

At all times, maintain humidity in your grow room between 45% to 60% .

Outdoor humidity control is out of your hands, so you must work with seasonal planting windows in your area. If you plant at the right time, your crops can start to veg within a time window where there’s agreeable humidity outside. 

Pot size

Three-gallon pot sizes are pervasive in cannabis cultivation for a reason. 

These pots allow your vegetative stage cannabis to grow a large root network that maximizes water and nutrient uptake and powers your cannabis plants’ vigorous growth spurt during vegging. 

Depending on the size of the crops you intend to grow, 1.5-gallon to 3-gallon pot sizes should be a good range for covering all your plants’ root coverage needs. 

pH levels 

Maintain pH levels between 5.5 to 6.5 throughout the vegetative stage. Consider investing in tools that help you monitor your daily soil pH - or water pH if you’re growing hydroponically. 


If your cannabis leaves are drooping or beginning to show symptoms of heat stress, you might not be adding enough moisture. During veg, water at least once daily in the mornings or evenings. 

The best indicator that you need to water your cannabis is when potting soil is dry to the touch. If you poke a finger into your potting solid and it remains dry up to your first knuckle, your weed plants are probably thirsty. 

Watering weed
Watering veg weed

How to identify male, female, and hermie marijuana plants

Sexing is important because potent marijuana comes from unpollinated female cannabis

It takes three weeks of growing weed - and four to five nodes on the stem - before you can determine the sex of your marijuana plants during the cannabis vegetative stage. 

Not separating your males and females will allow a single male plant to gleefully pollinate all females in your grow area, spelling disaster for your harvest and potentially lots of seeds in your weed. 

You can identify male and female cannabis plants by closely looking at the nodes as described below. Ideally, do this using a magnifying glass, high-powered phone camera, or a jewelry scope. 

Sexing male cannabis plants

You’ll spot little seed-like sacs sitting at the nodes of branches for male plants, and there’ll be no pistils shooting out. 

If you don’t take these crops out of your grow room before male pollen sacs pop open, all your females will be pollinated soon and your cannabis vegetative stage will be ruined if your goal was to have seedless marijuana.

Sexing female cannabis plants

With female cannabis plants, you’ll spot the same sacs at nodes, but this time, with white pistil hairs shooting out of each sac.

Identifying hermies

Under certain conditions, female cannabis plants may evolve into hermaphrodites - i.e., producing male and female organs on a single crop. 

In vegetative stage cannabis,

A hermie can be spotted when you find both sacs with no pistils and sacs with two pistil hairs shooting from the same plant node. 

A hermie won’t only self-pollinate. All females are at risk of pollination from the single hermie if you don’t take it out of your growing area immediately.

Hermie cannabis
Hermie cannabis

5 pitfalls growers should avoid during the cannabis vegetative stage

The vegetative stage of cannabis can be the longest. 

Taking measures to ensure everything goes right is the smartest thing you can do. Here are a few common mistakes to avoid to prevent yield losses and crop failure. 

Not sexing your plants 

As mentioned, to grow the most potent cannabis, you should only keep unpollinated female cannabis plants in your growing area. Not knowing how to sex your crops puts you at a high risk of a single male pollinating the entire room

With fans circulating air in your grow area 24/7, a single popped pollen sac can send spores across your entire grow room and pollinate all females in just hours. 

This results in weak-potency cannabis colas that are full of seeds. So always sex your vegetative stage cannabis plants early and take out all males so you can avoid such outcomes. 

Inadequate or inconsistent watering

Dehydration can destroy vegging plants’ vigor and put them at risk of heat stress. If you dip a finger into your potting soil and it feels dry up to your first knuckle, your crops are thirsty. 

Water vegetative stage cannabis plants at least once daily and stick to chlorine-free water to avoid chlorine toxicity

Inadequate nutrients and lighting

Your weed plants’ exponential growth must be powered by the right mix of cannabis vegetative stage nutrients during veg. Use your NPK in a 3-1-2 ratio during veg, and results won’t be half-bad. 

Lighting is crucial as well since the point of nutrient uptake is to synergize with photosynthesis. 

If there’s inadequate lighting in your room, it doesn’t matter how much nutrient mix you put into your growing medium since plants won’t have the opportunity to use those veg stage cannabis nutrients for photosynthesis and growth. 

Make sure plenty of light is reaching all leaves on your marijuana plant, not just the top. Consider techniques like trellising so light can efficiently reach all leaves inside your grow area.

Humidity control and circulation

The ideal relative humidity for vegetative stage cannabis is between 45% to 60%.

High levels unchecked in your grow room can create conducive grounds for diseases. While low humidity, on the flip side, may result in heat stress. 

Low levels can be addressed by placing a bucket filled with water inside your grow room. When humidity drops, the water duly evaporates to rebalance the room.

For high levels, however, you simply need to improve circulation. 

Without proper circulation and ventilation, humidity levels build up fast since cannabis plants constantly release water vapor from leaf pores/stomata during photosynthesis

Indica Dominant Marijuana Plant in Veg State
Indica dominant marijuana plant in veg stage

Vegging can be fun!

The rapid growth of the vegetative stage cannabis can be so exciting! You feel accomplished for growing phenomenal-quality weed by yourself as you watch your cannabis plants flourish. 

With these tips vegging your cannabis plant won’t seem as intimidating anymore, will it? Keep these guidelines on hand at all times and your veg stage will always run smoothly.

About the author: Derek LaRose

Also known as Kronic from The Cannabis Kronicles, Derek LaRose is a young ambitious cultivator and a staple educator for indoor cultivation.

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