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What are the Largest Cannabis Plants?

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Growing large cannabis plants is one of the recurring goals for every grower: greater height usually means more buds and more abundant harvests, both outdoors and indoors. But "large" is not the same as "productive": the varieties that stretch the most in height are almost always sativas or sativa-dominant hybrids, whilst many indicas yield heavily in a compact form.

In this guide we review the largest cannabis varieties – those that reach the greatest size and those that produce the most – and, most importantly, how to grow a giant plant step by step. If you're looking for high-yielding varieties, start with our feminised sativa seeds.

Table of contents

What is the largest cannabis plant in the world?

In outdoor grows with appropriate genetics, soil with direct access to roots and a long season, plants over 5 metres tall have been documented. Final size depends on three combined factors: the genetics, the root space and the duration of the vegetative growth phase. In other words, no variety reaches its maximum if the pot is small or if it flowers too quickly.

The largest cannabis varieties

We have selected six reference varieties. The first four stand out for their height and stretch; the last two (Big Bud and Northern Lights) are more compact in form, but make the list for their enormous yield. If your priority is performance over size, check out our guide on the most productive cannabis variety.

Variety Genetics Form (indoor / outdoor) Flowering THC Yield
Kali Mist Sativa 90% 1-2 m / 2-3 m 11-12 weeks High 300-500 g/m² · 500-600 g/plant
Moby Dick Sativa 70% 1.5-2 m / up to 3 m 10-11 weeks ~21% 500-600 g/m² · 750-1,500 g/plant
Amnesia Haze Sativa dominant 1.5-2 m / 2-3 m 10-11 weeks ~20-22% 550-650 g/m² · 700-1,000 g/plant
Power Plant Sativa ~85% 1-1.5 m / 2-3 m 8-9 weeks ~15-20% 450-500 g/m² · 500-800 g/plant
Big Bud Indica ~85% Compact 1-1.3 m / ~2 m 8-9 weeks Medium 550 g/m² · 600 g/plant
Northern Lights Indica ~90% Compact 1-1.5 m 7-8 weeks ~18% 500 g/m² · 600 g/plant

Kali Mist

One of the tallest and most classic sativas. Feminised, with sativa dominance close to 90% and high THC levels. Its flowering is long (11-12 weeks) and reaches 1-2 m indoors and 2-3 m outdoors. Energetic and lucid effect, more associated with daytime use. Its form and stretch make it ideal for those seeking plant volume.

Moby Dick

Sativa dominant (~70%) with THC around 21%, one of the major reference points for size and yield. Outdoors it easily reaches 3 metres and develops very voluminous structures; indoors it grows quickly, so it's best to move it to flowering early to control height. You can see the variety in our Moby Dick by Silent Seeds sheet.

Amnesia Haze

A very vigorous sativa-dominant variety with pronounced stretch, featuring 20-22% THC and a 10-11 week flowering period. Outdoors it easily exceeds 2 metres and responds very well to long seasons. It's one of the most sought-after Hazes for its combination of form, citrus aroma and potency: check out the Amnesia Haze available in the shop.

Power Plant

A South African sativa known for its fast growth and tall form. With a relatively short flowering time for a sativa (8-9 weeks), outdoors it stretches above 2 metres whilst maintaining a robust structure. A good option for those wanting height without an endless flowering period.

Big Bud (compact, very productive)

Not one of the tallest – its form is compact – but makes the list for its yield: dense and voluminous buds, up to 550 g/m² indoors and around 600 g/plant outdoors, with a flowering of only 8-9 weeks. Indica dominant (~85%), with a relaxing effect and fruity aroma. If you're interested in yield, compare it in our guide to most productive cannabis.

Northern Lights (compact, very productive)

One of the great indica classics (~90%), compact and of low form, precisely the opposite of "giant" in height. Its value lies in yield per size: around 500 g/m² indoors with a very short flowering period (7-8 weeks) and THC around 18%. Soft, earthy aroma, with hints of pine, and a relaxing effect.

How to grow giant cannabis plants

Choosing a high-yielding variety is only the starting point. These are the keys to taking it to its maximum size:

1. Genetics and root space

Start with a sativa or sativa-dominant hybrid and give it a large substrate volume: in pots, the larger the volume, the larger the plant; in soil, with direct access to earth, the potential skyrockets. As a reference, for monster plants outdoors, containers of several hundred litres are used or direct planting in prepared soil. If you're planning to grow big, consider our bulk seeds.

2. Long vegetative phase

Size is built during vegetative growth: the more weeks of vegetative (with 18 hours of light indoors), the more structure the plant will have before flowering. Outdoors, an early spring planting takes advantage of the entire season and is the most direct route to a huge plant.

3. Pruning and staking

So that a large plant doesn't collapse under weight or get out of hand, work on pruning and staking: techniques such as SCROG (crop net) distribute light and support branches, and apical pruning multiplies flowering points. Add stakes or canes for the main trunk as the buds fatten.

4. Substrate and nutrition

Use an aerated, nutrient-rich substrate with good drainage, and appropriate nutrition for each stage: more nitrogen in vegetative to drive development and transition to phosphorus and potassium in flowering. Keeping pH and EC in range prevents blockages that would slow growth.

5. Indoors versus outdoors

Outdoors is where these varieties express their full size potential, with no ceiling limit or wattage limit. Indoors size is determined by room height and light power, so control is prioritised (pruning, SCROG, early transition to flowering). For outdoor growing, check our feminised outdoor seeds.

Frequently asked questions

Does a sativa or an indica grow more?

As a general rule, sativas stretch more and develop taller, more open structures; indicas tend to be shorter and more compact. That's why the largest plants are usually sativas or sativa-dominant hybrids.

Can you get a giant plant in a pot?

Yes, as long as the pot is sufficiently large (the greater the volume, the larger the plant) and the vegetative phase is long. Even so, direct soil allows for larger sizes than any pot.

How much can a large plant produce?

It varies greatly depending on variety, technique and conditions, but outdoors giant varieties can exceed a kilogram per plant. If your goal is to maximise yield, see the guide on most productive cannabis.

When to plant outdoors to achieve maximum size?

The earlier in spring (respecting the end of frosts), the more vegetative time the plant will have before the photoperiod makes it flower, and the larger its final size will be.

Ready to grow your own giant plant? Choose your genetics from our feminised sativa seeds and get the most out of your grow.