How to Grow Small Cannabis Plants in Tiny Spaces

Published May 24, 2020

by Nebula Haze

Do you want to grow tiny cannabis plants? Would you like to build a “microgrowery” for your marijuana garden? This tiny plant tutorial will teach you how to grow cannabis plants that stay small yet still produce an abundance of weed! I’ve grown a lot of cannabis plants of all sizes, and I’ll share the most helpful tips and tricks to make cannabis plants grow in the exact shape and size you want.

Small plants are easy to hide, yet can still produce a surprising amount of weed. Here are some short cannabis plants I’ve grown:

LEDs are probably your best choice in a small space. This tent is only 3 feet (90 cm) tall.

Here is that tent just before harvest. Notice the size of the slinky compared to the plants. This tutorial will show you how to create short plants with rows of buds in a small space like this.

Example of Nebula's Microgrow - this mini grow tent was 2'x2'x3' with 4 autoflowering plants and used a HLG 100 LED grow light

This autoflowering plant grew into a tiny bud ball as a result of blue-spectrum LEDs and being topped after buds started forming (typically a no-no because it stunts autoflowering plants, but can be a good technique if you want to keep plants tiny)

I grew these plants in the same waist-high grow tent, but this time using a T5 fluorescent light. A T5 is another great choice for small spaces since they can be kept just inches away from plants. The downside is they produce more heat than LEDs. If you’re struggling with cold (for example growing a tiny garden in a garage or basement), fluorescent lights can help keep plants warm. If you want to minimize heat, LEDs are the way to go.

Then there’s the incredible world of solo cup plants. Restricted roots keep plants small. This autoflowering plant I’m growing now is just over a foot (30 cm) tall and buds are getting bigger every day.

 

Quick Summary (how to keep plants small without sacrificing yields)

Here’s a quick overview of the tutorial, then I’ll go into the detailed instructions below.

1.) Genetics

  • Choose a strain that naturally stays small – Today you have access to almost any genetics, almost anywhere in the world. Quick-to-harvest autoflowering strains are often the best choice for producing small plants, though short stature photoperiod strains can work, too. This tutorial shares several strains that have performed great for me in short spaces, and then I’ll share instructions on how to grow your plants so they stay as small as possible.

Certain strains like this Black Jack Auto naturally stay small, while still producing great yields!

Sweet Seeds Black Jack Auto - this plant grew thick and chunky colas

2.) Grow Setup

  • Use the right grow light – Fluorescent lights (like CFLs or T5s) and certain LEDs are great choices for small grow spaces. I’ll break down the pros and cons of each and share the specific models that have kept plants short for me.
  • Light spectrum – Grow lights with more blue in the spectrum tend to keep plants short, while grow lights with more red can encourage stretching.
  • Restrict root space – Plants in big pots can become the size of trees! Keeping plants in smaller pots tends to keep them from getting as big (like a bonsai tree with restricted roots), but buds will still get fat as long as the plant is receiving plenty of light and nutrients.
  • Pick a “short” grow style – Short plants are often created through one of these grow styles: “Sea of Green” (many small plants in small pots), “Screen of Green” (using a screen), Manifolding (massively manipulate plant shape at a very young age), or other types of plant training (more on that below).

Restricting root size also restricts overall plant size

3.) Growing Practices

  • Keep grow lights as close as possible – Make sure your grow light is as close as possible without stressing plants. Strong light helps keep plants shorter.
  • “Top” your plants – Cut off the top tip of the plant when it’s just a few weeks old. This technique is known as “topping” and causes plants to grow bushy and spread out as opposed to tall like a Christmas tree. As a bonus, you create extra bud sites for free.
  • Plant training – Learn how to get any plant to stay the exact height and shape you want via “plant training” techniques. Even if your plants are already too big, this can help. Especially techniques such as LST (low stress training) and supercropping (extreme bending) can come in handy if you need to change your overall plant shape or reduce the height.
  • Don’t wait too long to initiate flowering – This doesn’t apply to auto-flowering strains, but if you’re growing a photoperiod (regular) plant, initiate the flowering stage when the plant is half the final desired size. Plants typically double in size after receiving a 12/12 light schedule. Plant height can get out of control if you wait too long. I learned this one from experience!

Bending and tying down stems can be used to keep a cannabis plant almost totally flat

Example of a "manifold" that was made without any topping - just bending and LST

 


 

1.) Genetics

Choose a strain that naturally stays small

Some cannabis strains tend to grow really big and tall no matter what you do. If a strain is labeled as “XL”, stay away! However, some strains stay super small without you having to do much of anything.

Auto-flowering strains start making buds in about 3-4 weeks from germination and are typically ready to harvest in 2-3 months. Due to this quick life cycle, nearly all auto-flowering strains stay on the smaller size. However, look for autoflowering strains listed as being short if you want the smallest possible plants.

Check this out: How to Research and Find the Perfect Strain

Recommended short auto-flowering strains

  • Amnesia Auto by MSNL – I’ve harvested 3 of these plants and highly recommend the strain. They stayed small, grew sparkly buds with cerebral strong effects, and produced good-to-great yields
  • Berry Auto by G13 Labs – Fruity strain that stays short, grows easily, and is ready to harvest quickly
  • Black Jack Auto by Sweet Seeds – These plants naturally stay small while still producing great yields. If any branches get tall, they respond well to training. I really enjoyed the bud effects of this strain. They’re strong yet kind of unique. It reminds me of a sativa/haze with more of a body stone.
  • Blue Critical Auto by Dinafem – The Blue Critical I grew stayed small, bushed out on its own, responded extremely well to training, and buds came out fat and super potent! A joy to grow.
  • Cinderella Jack Auto by Dutch Passion – When I grew this strain, the plant stayed small and produced solid, dense buds. The buds ended up being popular because the effects were curiously strong and long-lasting.
  • Cream Cookies Auto by FastBuds Seeds – The bud quality is out of this world. And look beautiful in pictures! Each plant stays short, is easy to grow, and yields well.
  • Cream Mandarin Auto by Sweet Seeds – This strain tends to stay very small, sometimes almost runty. Although the citrus-smelling buds aren’t the biggest, they’re ready to harvest quickly and produce captivating effects.
  • Pineapple Express Auto by G13 Labs – An extremely popular autoflowering strain; plants stay short, are quick-to-harvest even for an auto, and the sparkle-encrusted buds smell like heaven.
  • Pink Kush CBD 30:1 by Seedsman – Medicinal strain with under 0.5% THC, beautiful buds, quick-to-harvest
  • Red Poison Auto by Sweet Seeds – This breeder has created several epic autoflowering strains, but the Red Poison Auto may be my favorite. I love the crazy red/purple color (which shows up on most plants, especially if the plant gets cool nights close to harvest), good yields, and dreamy bud effects.
  • Tangerine Dream Auto by Barney’s Farm – The intoxicating smell of citrus on a tiny, high yielding plant. What more could you want?
  • THC Bomb Auto by Bomb Seeds – I’ve grown 5 different plants of this strain over multiple grows in different setups, and every one came out excellent. Easy to grow, great yields, beautiful sparkly buds, and potent. Highly recommended!
  • Wedding Cheesecake Auto by FastBuds Seeds – Stays pretty small, quick to harvest, and buds produce powerful effects.

This Amnesia Auto by MSNL stayed small but produced a surprising amount of bud!

Decent sized buds for the compact size

THC Bomb Auto grows thick buds without needing a lot of height, and buds are POTENT

You can also choose photoperiod plants listed as “short” strains. Strains listed as “FAST” or “Express” may be candidates for a short grow space because they have a quick flowering period, but it’s good to read the description to learn more about what height to expect. Photoperiod plants typically get bigger than autoflowering plants, but they can be a great choice for a small space as long as you get a suitable strain and make sure to initiate the flowering stage when plants are 3-4 weeks old. Don’t let them get too big before you initiate 12/12 or they’ll overgrow your garden!

Recommended short photoperiod strains

  • Aurora Indica by Nirvana – Plants are fast-growing with dense, potent buds, yet they stay short and are ready to harvest quickly.
  • Candy Kush Express FAST by Royal Queen Seeds – Easy to grow and quick to harvest. Buds smell divine and effects are extremely relaxing.
  • Cream Caramel FAST by Sweet Seeds – Great yields on such a fast-flowering plant, tantalizing bud smell, and lovely effects.
  • Original Amnesia by Dinafem – This strain isn’t particularly quick to harvest but doesn’t get very tall. Plants respond positively to plant training including manifolding. Buds are big and beautiful, with effects that live up to the name “amnesia”
  • Peyote Critical by Barney’s Farm – Trippy effects on this strain. Plants stay short with training. Try to initiate the flowering stage before 4 weeks from germination and it shouldn’t get too big.
  • Romulan – This strain is extra popular where I live right now. Romulan plants stay short and buds are high in THC. Although it doesn’t have the best yields, the bud quality is worth it.
  • Royal Cookies by Royal Queen Seeds – Created from the extremely popular Girl Scout Cookies Forum Cut, this strain delivers beautiful American genetics with a punch, and plants stay small enough for a stealthy garden.
  • Speedy Chile FAST by Royal Queen Seeds – Grow ultra sparkly buds on a tiny plant. The effects are relaxing and may help with anxiety.
  • Sweet Russian by Garden of Green – Nice looking buds, stays small, yields well, good effects.
  • Sweet Tooth by Barney’s Farm – I’ve grown this strain a few times over the years, and it always stays short with good effects. However, BF seems to be improving and refining this classic strain for potency because when I grew this strain again last year, the buds felt more powerful than ever. Highly recommended!
  • THC Bomb by Bomb Seeds – Stays small, yields big, with excellent potency and sparkly buds. Can’t go wrong with this one.

Aurora Indica stays short and produces tons of buds

Aurora Indica cannabis plant is covered in buds!

Original Amnesia responds well to plant training such as being manifolded

Original Amnesia in regular light

 

2.) Grow Setup

Use the right grow light – CFLs, T5s, and certain LEDs are great choices for small grow spaces. I’ll break down the pros and cons of each and share the specific models that have kept plants short for me.

CFLs give a lot of flexibility in tiny spaces because they’re small and can be kept just inches from plants. How to grow with CFLs.

Unstacked top with 138W of CFLs placed inside

This is my very first short plant, grown under a few big CFLs.

The plant was less than 1′ tall at harvest yet produced 1.5 ounces of bud. CFLs can produce good yields with small plants, but CFL bulbs that are big (or a lot of small CFLs) get hot and expensive. If you have space, I recommend upgrading to more efficient grow lights than CFLs.

This cannabis plant was trained in the vegetative stage to grow short and bushy, now it's buds are fat from being so close to the grow lights

T5 fluorescent lights are low profile, can be kept close to plants, and produce surprisingly good yields if you train plants to grow wide and flat like the plants here. The downside is they get much hotter than LEDs for the same electricity, and the yields aren’t as good per watt. How to grow with a T5 grow light.

LEDs come in a variety of shapes and sizes, so they can fit almost any setup. LEDs tend to be low on heat and electricity usage, which makes them great for small stealthy gardens. LED yields are excellent, too. On average, LEDs produce about twice the amount of dried flower as fluorescent lights like CFLs and T5s for the same electricity. The newer models of LEDs can yield even more. How to grow with LEDs in a mini tent.

These plants were grown in a 2’x2’x3′ tent under a 100W Quantum Board LED like this MarsHydro TS 600 (which is “600W equivalent” but actually only uses 100W)

The inside of Nebula's microgrowery - look at all those colas growing under the 100W HLG Quantum Board LED grow light

Here is an example of the buds produced! (This was Auto Amnesia by MSNL)

 

Light spectrum – Grow lights with more blue in the spectrum tend to keep plants short, while grow lights with more red can encourage stretching. LEDs or bulbs labeled with a spectrum of 4000k, 5000k, and 6500k are great choices with plenty of blue to keep plants short.

This graphic represents the colors in visible light. Blue light encourages plants to stay short and bushy. Red light tends to cause marijuana plants to stretch and grow tall.

Where ultraviolet B light is located on the light spectrum

Restrict root space – Plants in big pots can become the size of trees! Keeping plants in smaller pots tends to keep them from getting as big (like a bonsai tree with restricted roots), though buds will still get huge as long as the plant is receiving plenty of light and nutrients.

Keeping plants in a small container causes them to stay smaller on average by restricting root size. This autoflowering plant grown in a solo cup barely grew to a foot tall.

These autoflowering plants were all germinated at the same time and even share 4 of the same strains. The little tent had 1-gallon pots, while the bigger tent used 3-gallon pots. The smaller pot size is a big part of why the plants in the mini tent stayed so much shorter and smaller.

Here’s another example showing how pot size makes a difference to plant size. These plants were all germinated at the same time in Rapid Rooters. Right before this picture I planted some of the seedlings in 3-gallon pots, and the others in solo cups. They were all about the same size at this point.

Within a week, the plants in bigger pots overtook the plants in solo cups. Most actually had an extra set of leaves compared to their solo cup siblings. The size difference would only have kept getting more vast if these plants were allowed to continue growing together. Small pots make small plants! Here’s a timelapse of that week if you want to check it out.

Pick a “short” grow style – Short plants are often created through one of these grow styles…

  • Sea of Green (SoG) keeps many small plants in small pots
  • Screen of Green (ScrOG) trains plants to grow along a screen or net, which forces them to stay about the same height
  • Manifolding is a process that massively manipulates plant shape at a very young age for a bushy, symmetrical plant
  • Other types of plant training such as Low Stress Training (LST) and Supercropping (extreme bending) can also be helpful to keep plants short

Sea of Green (SoG) – Many small plants

Example of a Sea of Green (SoG) marijuana setup - by growing many small plants, you can create an even canopy of buds without any plant training

Amazing example of well-trained cannabis plants - training your plants this way can increase your yields by up to 40%

Screen of Green (ScrOG) uses a screen or net

ScrOG in a Deep Water Culture (DWC) marijuana grow

Here’s another example of a net being used to help keep plants short and flat

LED grow lights can make plants look purple and black in pictures

Manifolding creates a solid main trunk with several symmetrical branches. This allows you to achieve monstrous yields on a relatively small plant.

Example of a single plant that was manifolded and trained so it would produce as much as many smaller plants

Other types of pruning and manipulation such as Low Stress Training (LST) and Supercropping (extreme bending) can be used to create almost any size or shape plant

Example of an auto-flowering marijuana plant that was trained with LST but not topped - just before harvest

 

3.) Growing Practices

Keep grow lights as close as possible – Make sure your grow light is as close as possible without stressing plants. Strong light helps keep plants shorter. How far should I keep my grow lights?

“Top” your plants – Cut off the top of the plant when it’s just a few weeks old. This technique is known as “topping” and causes plants to grow more spread out as opposed to tall. You want a short bush, not a tall Christmas tree. Learn all about topping.

“Top” your plants when they’re 3-4 weeks old

A good time to top a plant is when it has about 6 sets of leaves

Example of an auto-flowering plant that is at the upper limit of when to be topped

To top a plant, you cut off the top by clipping through the main stem

Definition of "topping" cannabis - Topping means to cut off the top of a stem. It can refer to the main stem, but also other stems can also be topped. Example of topping a plant - topping instantly splits one stem into two new main stemsTopping makes plants grow more wide and bushy instead of tall. As a bonus, it increases the total number of main bud sites and improves yields!

See the natural "Christmas tree" growth pattern vs a plant that has been FIMed or topped

Autoflowering Tip: Top an autoflowering plant after it’s already started making buds to keep it shorter. Topping in the flowering stage is normally considered a bad idea because it stunts most autoflowering plants, but can be a good tactic if you want to stunt the plant on purpose.

Topping after buds had already started forming caused this plant to stay extra small.

Here’s another example of a plant that was topped after it had already started making buds

 

Plant training – “Plant training” techniques give you ultimate power to create plants of nearly any size or shape.

Training techniques such as LST (low stress training) and supercropping (extreme bending) are especially handy if you need to change your overall plant form or reduce the height.

The grower wants to keep plants as short as possible

Example of training on auto-flowering cannabis plant - before LST

As the plants grew, she regularly bent all the top branches over and tied them down

Example of training on auto-flowering cannabis plant - aftter being bent and secured via LST

That’s how these tiny plants were made!

These cannabis plants were grown in coco in smart pots (fabric containers) and thrived even though they were regularly exposed to too-hot temps

Use bending to reduce the height of tall branches. Don’t forget to tie the branches down or they’ll turn back up! (I like plant twist tie for hooking around stems)

After bending/LST use something like plant twisty ties to secure stems in place (or they'll soon grow right back up to where they were!)

The arrow points to the twist tie that was used to hold down the branches as this plant grew

Example of untopped plant that has been trained purely with LST - the arrow points at the main stem, which has been bents completely over

Use supercropping to bend at right angles without breaking your stems. This can be especially helpful if you’re plants are already too tall for your space.

To bend a really stiff stem, pinch tightly, wiggle gently until you feel/hear crunching, then slowly bend and secure.

Some growers take plant training to extreme levels

Example of an auto-flowering cannabis plant grown in coco coir - it has been trained to grow lots of buds

Check out the “skeleton” of the above plant after harvest. The grower basically trained the main stem to grow in a flat spiral around the base. So much bud in such a small area!

Highly LST'ed plant at harvest - view from above

You can produce impressive buds on a small plant with a powerful grow light and high-yielding genetics

Crazy example of LST (low stress training)

It’s amazing what can be accomplished with a little bending and tying down as your plant grows!

A different PPP using the 4-way LST method by LBH

Don’t wait too long to initiate flowering – This doesn’t apply to auto-flowering strains, but if you’re growing a photoperiod (regular) plant, initiate the flowering stage when the plant is half the final desired size. Plants typically double in size after receiving a 12/12 light schedule, so plant height can get out of control if you wait too long.

In order to get a cannabis plant to enter the flowering stage and start making buds, a grower needs to use a timer to put the grow lights on a 12/12 light schedule (12 hours light, 12 hours darkness)

Initiate 12/12 when your plant is about half the final desired size

Plant about double in height before harvest, though some strains “stretch” more or less (notice how the back left plant from the above tent got taller than the rest). Genetics make a huge difference! Learn more about the flowering stretch.

Cannabis plants growing under a 315 CMH grow light (not long before harvest)

You should now have a solid understanding of what it takes to grow marijuana plants in any size or shape you want!

 

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