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How long do you veg before flipping to flower?

Deciding when to switch your cannabis plants from the vegetative stage to the flowering stage is one of the most important decisions a grower has to make. The length of the vegetative stage determines the size your plants will reach before starting to produce buds. Generally, the longer you veg, the larger your plants will get. However, there are diminishing returns after a certain point, and leaving plants in veg too long can be counterproductive. Most growers aim for a veg time of 4-8 weeks. Here’s a quick overview of how long you should veg for different situations:

Quick Veg Times

– Sea of Green style grows: 2-4 weeks
– Small, compact indoor strains: 4-6 weeks
– Most indoor grows: 5-8 weeks
– Large sativa-dominant strains: 6-10 weeks
– Monster crops for outdoor grows: 8-12+ weeks

The exact length will depend on factors like your growing space, plant count, strain, and training techniques. As a general rule, veg your plants until they’ve filled out their allotted space, but before they become rootbound or unmanageable. Read on for more details on dialing in the perfect veg time for your situation.

Why the Vegetative Stage Matters

The vegetative stage is a critical part of the cannabis plant’s life cycle. This is the period of active growth during which plants focus on developing roots, stems, and leaves rather than producing flowers. During veg, your plants will increase in size exponentially if given enough light, nutrients, and root space.

The size your plants reach during the vegetative stage dictates their potential bud production in flowering. Bigger plants equal bigger yields. However, vegging too long wastes time and energy, causing plants to become overgrown. Finding the optimal veg time allows plants to fully fill the grow space while avoiding diminishing returns.

Vegging for the right duration helps maximize the growth potential of your plants. It allows sufficient time for them to develop robust root zones and branching structures suited for abundant flowering. Getting the veg time dialed in perfectly takes some trial and error based on your setup and strains. With experience, you’ll learn the optimal veg times to maximize your yields.

Factors That Determine Optimal Veg Time

Many variables influence how long you should vegetate cannabis plants before flipping to flowering. The major factors include:

Growing Space

The size and shape of your grow area dictates how long you can veg plants before space becomes limiting. For example, in a small grow tent or cabinet, you’ll want a shorter veg time to avoid plants becoming rootbound. With an open basement or warehouse, you can veg much longer since plants have endless room to expand.

As a general guideline, veg indoor plants until they’ve filled 50-75% of the allotted space. This allows some additional stretch when you switch to flowering. If your grow area has a height limit, don’t veg past the point where plants reach that height.

For outdoor grows, veg duration depends on the final size you want rather than space constraints. You can veg outdoor plants as long as needed to achieve your desired plant size.

Strain Characteristics

Some cannabis strains grow much larger and stretchier than others. Tall, lanky sativas need longer veg times to fully fill out before flipping to flowering. More compact indica varieties can get by with shorter veg durations.

If you’re unsure how tall a strain may get, check with the breeder or look for grow journals online. Use the estimated height along with your space to determine appropriate veg times. Stretchy sativas often benefit from 6-10 weeks or more in veg before the flip.

Plant Count

The number of plants you’re growing in your space also helps determine optimal veg time. For example, a Sea of Green style grow with 20-40 small plants per square meter will only need 2-3 weeks of veg before flipping. With fewer larger plants at 1 plant per square foot, you’d veg for 6-8 weeks.

In general, the more plants you’re growing in a given space, the less you need to veg each one before inducing flowering. Closely spaced plants will rapidly become rootbound if vegged too long.

Training Techniques

How you train your plants during vegetative growth allows them to fill space faster than untrained plants. Strategies like topping, low stress training (LST), and scrogging make plants shorter and bushier. Well-trained plants usually don’t need as long of a veg period to fill the grow space.

Let the training techniques you plan to employ help guide your veg time. For example, aggressively trained SOG plants may only need 2 weeks of veg. Less extreme training can still shorten veg times compared to untrained plants.


The amount of light your plants receive during veg also influences growth rates and optimal veg time. Bright lighting with an optimal DLI accelerates growth compared to dim lighting. Upgrading your lights can allow for faster veg times.

Conversely, weaker lighting like CFLs or blurples will slow plants down, necessitating longer veg times. Match your veg period with the intensity of your lighting for best results.


Optimizing your nutrient regimen for fast but healthy vegetative growth helps reduce veg times. Use vegetative stage nutrients with higher nitrogen levels to fuel rapid foliage growth. Keep dialing in your regimen to find the sweet spot between vigor and excess.

Plants limited by nutrients will grow slower and need longer veg times. But excessive nutrients can be counterproductive too. Find the ideal balance for your strains.

Ideal Veg Times for Common Grow Setups

Here are general veg time guidelines for some of the most popular grow setups:

Sea of Green Grows

A Sea of Green (SOG) setup involves growing many smaller plants at a high density. The goal is to produce a “sea” of buds rather than large individual colas. SOG grows work best for indica-dominant strains in shorter veg times of:

– 2-3 weeks for aggressive SOGs with tiny plants
– 3-4 weeks for moderate density SOGs

Since plants grow very close together, you want to limit vegetative growth to avoid overcrowding. SOG plants shouldn’t get too tall before flipping to flower.

ScrOG Grows

Screen of Green (Scrog) techniques use netting to fill a grow space evenly with many bud sites. A 3-5 week veg period is common for Scrog setups. This allows plants to establish an even canopy before flowering.

Longer veg times from 6-8 weeks work for advanced Scrogs aiming to fill bigger spaces. But take care not to veg too long or plants become difficult to train through screens once flowering begins.


Mainlining is a training method that builds plants into evenly spaced, multi-top plants. It involves topping repeatedly to create a desirable “manifold” shape. Plants are vegged until the manifold fills out, which usually takes 4-6 weeks.

Strains that respond well to mainlining with even branching may veg for 6-8 weeks before the flip. This ensures the manifold is complete.


Less intensive training like topping and LST shortens veg times compared to untrained plants. Regular topping or LST over 3-5 weeks reduces vertical growth while bushes out plants.

Aim for a 2-4 week veg when using moderate training. The exact duration depends on how aggressively you train and how plants respond.

Untrained Plants

If you don’t train plants at all, you’ll need moderately longer veg times to fill your space. Untrained indicas may need 5-6 weeks of veg before becoming crowded.

Expect to veg hazy sativas or stretchy hybrids for 6-8 weeks or longer before they’re ready for flowering. This allows more vertical growth while retaining some side branching.

Monster Crops

For outdoor grows where space isn’t limited, you can veg plants as long as needed to achieve huge yields. Monster cropping aims for plants from 6-8 feet tall or more at harvest.

This requires prolonged vegetative growth, often for 8-16 weeks. Some extreme monster crops may even veg for 6 months! This depends on your climate and the strains’ size potential.

Autoflowering Strains

With autoflowering strains, the vegetative period is set by genetics rather than light cycles. Most autoflowers only veg for 2-4 weeks before entering flowering automatically.

You generally don’t have control over veg time with autoflowers. Simply give them adequate light and nutrients until flowering starts on its own.

Signs that Plants are Ready to Flower

Rather than sticking to a predetermined veg time, some growers prefer to let the plants tell them when they are ready for flowering. Watch for these signs that cannabis is reaching the end of the optimal veg window:

– Leaves growing out the sides of pots or reaching grow area boundaries
– Lower leaves yellowing from lack of light penetration
– Nodes growing extremely tight together on stems
– Root tips becoming visible at the surface of containers
– Growth noticeably slowing down or stunting
– Canopy getting bushy and difficult to train/work around

Any of the above are good indicators your plants are prepared for the hormonal changes of flowering. Allowing plants to outgrow your space is counterproductive. Another week or two of veg won’t make up for the lost light penetration and root binding.

Benefits of an Optimal Veg Time

Getting your veg time dialed in perfectly provides the following advantages:

– Maximize yields from your space and lighting
– Produce evenly developed, healthy plants ready for abundant flowering
– Avoid overgrown, rootbound plants that underperform
– Minimize unnecessary veg time for faster turnaround times
– Simplify training and plant maintenance
– Even, well-filled canopies for optimal light exposure
– Bigger, more developed root systems to support bigger fruits

Proper vegging sets your plants up for maximum productivity when you switch to flowering. Take the time to monitor plant development and learn ideal veg durations.

Disadvantages of Vegging Too Long

While some extra veg time can increase yields, going overboard has many downsides:

– Stunted, rootbound plants with growth issues
– Out of control plants that no longer fit the space
– Excessive stretch and difficulty training plants
– Lower buds not developing properly due to lack of light
– Increased watering demands straining your system
– Inviting pests, mold, and other problems
– Light not penetrating properly to lower canopy
– Time and energy wasted on excess vegetation
– Too much foliage trimming and maintenance required

it’s better to harvest a few weeks earlier than to let your plants veg out of control. Keep veg times within reason for your setup to avoid headaches when flowering begins.

Tips for Determining Optimal Veg Time

Here are some tips to help dial in perfect veg times:

– Start conservatively with less veg time your first grow, then increase if plants seem undersized
– Take detailed notes each grow on veg times and resulting plant sizes
– Account for the stretch factor of different strains after flipping
– Train plants during veg to control size and shape
– Avoid excessive pruning and defoliation in late veg
– Pay close attention to internodal spacing and foliage density
– Let root system size help guide readiness for flowering
– Watch for preflowers to form, signalling prime time to flip
– Flip a portion of plants at different times to compare results
– Consider light intensity and DLI in veg time decisions
– Adding CO2 enrichment may allow slightly shorter veg periods

Getting your veg dialed in takes some learning and experience. With good observations and records, you can zero in on the optimal flip timing for your setup and strains.

Frequently Asked Questions

What is the best veg time before flowering?

The ideal veg time for most indoor grows is 4-6 weeks. Very small SOG grows can get by with 2-3 week veg times. Larger plants may need 6-8+ weeks depending on strain and training. Outdoor plants can veg even longer based on the desired final size.

Can plants veg too long?

Yes, allowing plants to outgrow your space leads to problems. Extended veg times beyond 8-10 weeks indoors often causes overcrowding and stress. Vegging too long wastes time and energy that could go into flowering more harvests.

Do autos need less veg time?

Autoflowering strains have a genetically fixed vegetative period of 2-4 weeks. You don’t control their veg time since they start flowering automatically. Some autoflowers may benefit from 1-2 extra weeks in veg for yield boosts.

Can you reveg after harvesting?

Yes, you can put plants back into veg after harvesting by providing 18+ hours of light. This triggers new vegetative growth for a second harvest outdoor or perpetual harvests indoor. Revegged plants need 4-6 weeks to regrow before re-flowering.

What light cycle for veg stage?

The vegetative stage requires at least 18 hours of daily light, but many growers use 20-24 hours of light for optimal growth. Only switch to a flowering light cycle of 12/12 once plants are ready to begin blooming.


Determining the ideal length of cannabis’ vegetative stage before inducing flowering is crucial for maximizing yields indoors and out. While strain, space, lighting, and other factors influence veg times, a range of 4-8 weeks is optimal for most small to medium indoor grows.

Take detailed notes on your veg times and plant development each grow. Monitor for signs like slowing growth, crowded nodes, and rootbound plants to know when cannabis is entering the ripening phase and ready for the hormonal flowering trigger. Avoid excessive veg times that cause plants to outgrow your space.

Dialing in the perfect veg duration for your setup and strains takes experience, but pays off with healthier, more productive plants and bigger yields. Use this guide to determine suitable vegetative periods, then refine as you learn your plants’ needs. Once you find your optimal veg time, you can replicate it grow after grow for consistent results.