How to Clone Weed in a Cup of Water

Last updated May 27, 2026

by Nebula Haze

Did you know you can clone cannabis plants in a cup of water? (Where to get seeds safely online)

Cut off a longer stem.
Immediately put in water.
Roots form in a few weeks.

Who doesn’t want a bunch of free cannabis plants when it’s this easy?

Leave your cup in a warm sunny spot with filtered light, and wait several weeks for roots to form. Some clones take as little as 2 weeks, most have roots by 4 weeks. I once had a clone that took 6+ weeks. Aeroponic cloning is faster, but this is easier.

Roots form in 2-4 weeks (stubborn strains may take longer)

I personally have had great luck with clear cups, but opaque cups can help keep light away from the roots, so they’re recommended if available.

Put a rooted clone in soil, coco, or hydro, and you’ve got a new free cannabis plant!

Each of these cuttings is an exact copy of the “mother” plant. As a result, you know that all these clones will grow pretty much the same as each other (and their mum). Cloning is also a great way to produce a lot of plants at once for basically free.

I always use clones for my side-by-side grow experiments.

If buying seeds is too expensive (and creating your own seeds isn’t feasible), then cloning can make growing cannabis a lot more affordable. Cloning via the “cup method” is easy and doesn’t take much space, effort, or equipment.

This tutorial will teach you how to make rooted clones like this, in a cup of water.

Note: Other cloning methods (particularly aeroponics) make clones grow roots faster. But they’re not as easy.

Learn about buying cannabis clones online if you’re in a real hurry.

Genetic Variation: Some plants are easier and harder to clone than others. It’s not just your skills as a cloner but also genetics and individual variation. Even in professional setups, some strains are slow or hard to clone. So don’t take it personally if a particular strain doesn’t make roots quickly.

How to Clone Marijuana with the Cup Method

This section will take you through the process of cloning step by step. First, you will need a few supplies…

Supplies list

A cannabis plant with 7″ (18 cm) long branches (these stems become your clones)
Sharp scissors
Fresh clean water (spring water is great, but any human-drinkable water will work)
A cup or container to put your clones in immediately after cutting

Supplies needed for this cloning tutorial (cannabis plant, scissors, water, and a cup)

Optional but not necessary

Cloning powder and/or cloning gel

The little plants in this picture used to be branches on the plants behind them. Each is a genetic copy of their “mother” cannabis plant.

Will using clear cups hurt the roots? I’ve tried cloning in clear and not-clear cups. As far as I can tell, it didn’t seem to make a difference in rooting rates. I wouldn’t let direct light shine on the roots and make the water hot, but a little ambient light doesn’t seem to bother them.

That being said, if you’re worried the water might get a lot of extra light, then use opaque cups.

I’ve cloned in clear cups and opaque cups like this. Both seem to work the same.

You can clone cannabis in basically any cup or container. This clone made roots in a glass beaker after being left on the kitchen counter. However, small clones take MUCH longer to make roots than bigger ones.

And any clone that takes a long time to root usually isn’t the most vibrant plant. This plant took 30 days to make roots, and then took another 3 weeks to really “get going” as a seedling.

If you want cannabis plants as fast as possible, it’s usually faster to plant a seed than make a clone.

Step-By-Step Cloning Instructions

If this is your first time taking cannabis clones, I recommend only taking cuttings from a vegetative plant that hasn’t started flowering yet.

A vegetative plant is only growing stems and leaves, but no pistils or buds yet. Plants in the vegetative phase tend to root more quickly and easily.

On the other hand, clones taken during the flowering stage may take longer to make roots, and sometimes display odd growth patterns for the first few weeks after rooting. Some people take flowering clones on purpose to take advantage of those growth patterns. This is known as monstercropping but is considered an advanced growing technique.

The goal is to have a rooted clone by the end of the tutorial. Then I’ll show you how to plant your clone in soil, coco, or hydro.

Can you clone autoflower cannabis plants? Not recommended. It’s advised not to take clones from autoflower plants because they often start flowering before they make roots.

Set Up – Prepare for cloning

Get all your cloning supplies ready before you get started. Get your cannabis plant, your glass of water, your scissors, and put them all in the same place so you can smoothly cut clones and stick them immediately in water.

Prepare your space with your plant, scissors, water, and cups. Don’t forget to label your cup with the strain name!

What about cloning gel or cloning powder? You can dip the ends of stems into cloning gel and/or cloning powder, which may help them root more quickly. Many growers find they help plants root faster, but when it comes to this method, I’ve never really noticed much difference between clones that get dipped vs not dipped. However, it definitely can’t hurt and may help you in your individual environment.

What’s the best water to use? Spring water is my favorite water for cloning (or growing) weed. It doesn’t have all the minerals removed like filtered water or distilled water, and often has a lot less extra random “stuff” than tap water.

Cannabis clones typically respond well to spring water. That being said, I don’t have the option to use spring water all the time so I use tap water. Our local tap water is not great, with high PH and PPM. Yet it works great for growing and cloning weed. Based on my experience talking to other growers, it seems like nearly all human-drinkable water sources work for weed clones to take root.

If your tap water is good enough to drink, it’s good enough for cup cloning (as long as you correct the pH!)

Should I use nutrients in the water clones drink?

I have cloned cannabis in straight spring water as well as with seedling strength nutrients. I have heard the conventional grower wisdom is to use no nutrients and just plain water, because that encourages faster rooting. I have never run dedicated side-by-side experiments, but I didn’t know the convention before I started using this method, and in my experience both seemed to work equally well.

That being said, I don’t include nutrients when cloning cannabis, because nutrients can encourage other stuff to grow in the water (algae, bacteria, etc.).

Any way to prepare the mother plant to make faster clones?

One difference I have noticed is clones seem to root a little faster if the mother plant is a bit pale/low on nutrients, and also if the mother plant is growing fast. I think the clone desperately grows roots to find nutrients and keep up with the growth.

Whereas if the leaves are dark green and full of nutrients, or the mom plant is slow-growing, the clone seems more like to just “live off” the nutrients in the leaf without necessarily being in a hurry to grow roots or get bigger.

So it’s good to pick a fast-growing mother and then not give nutrients for a week before cloning if possible. Get those branches growing fast and craving nutrients so they grow roots as fast as possible.

Step 1 – Identify which branches are at least 7″ (18cm) long on your vegetative plant

For first-time cloners, I recommend cutting clones that are around 7″ (18 cm) tall. That means you need to identify which branches on your plant are at least that long or longer. This size will fit in a typical drinking glass with the leaves able to reach over the top of the glass and “spread their wings” to the light.

Your clones should be big enough to reach over the top of your cup

You can cut a clone that’s shorter than 7″ (18 cm). I’ve successfully cloned a stem as little as 3″ tall). However, shorter clones typically take longer to root and aren’t as vibrant plants on average.

I had one 4″ cutting that didn’t make roots after several weeks. Out of curiosity, I just let it keep going and refilling the cup as the water level got low. I was amazed when it finally sprouted roots 2 months later. If your stems aren’t long enough yet, follow the tips below to get them to quickly grow longer.

How do I make my plant produce longer stems for clones?

If the stems on your plant are too short (or there aren’t many suitable clone sites or offshoots), you need to encourage the plant to branch out and give the stems time to lengthen
If you haven’t yet topped the plant, do it now (cut off the top tip of the main stem). This will cause the plant to naturally bush out and develop more side branches.
A stem on the plant won’t develop without light. Try to gently open up the plant via bending and tie the tallest branches down so all the small shoots get light and start growing.
Give strong light to your plant so all the newly-exposed shoots grow quickly
But not too much light. Make sure to follow the manufacturer’s instructions on how far to keep your grow light from plants. Keeping a grow light too close to the plant can slow down plant growth to a crawl. It also tends to keep branches shorter. Learn how too much light can cause light stress.
Make sure to deal with problems quickly so your plant grows as fast as possible

If you follow these instructions, it should only be a week or two before you have several suitable clone sites.

This stem is 7″ (18 cm) long. Perfect!

What about bigger/taller clones than 7″ (18 cm)? You can definitely take big clones. I’ve seen some growers take 12″ (30 cm) clones or even bigger, especially when using an aerocloner.

Big clones can root in the right environment and one advantage is the plants are already well developed. If you’ve got long branches and want a bunch of tall plants right away, you can often turn those branches into big clones. However, bigger clones can be more likely to wilt immediately because they have a difficult time getting water to their tallest leaves and branches. The other issue with big clones is they already have a set stem structure. With smaller clones, you have the ability to shape the size and shape of the clone via plant training, which can dramatically increase your overall yields indoors under a grow light.

Step 2 – Trim the branches until there are only the top two pairs of leaves

You’re cleaning up the stems so you don’t have leaves sitting underwater in the glass. It’s easier to clean the sides of the stem now than after the clones have already been cut.

Trim the branches in preparation so they’re mostly smooth

I typically leave the top 2-4 fully formed leaves, but each clone is a little different. Make sure there are at least 2 leaves left!

Step 3 – Cut off your clone and immediately put in water

It’s go time! You are about to cut your clones!

Don’t forget to label your cups with the name of the strain because it’s easy to forget which is which.

Try to cut at a 45-degree angle, and make your cut near a node/set of leaves if possible (this may help clones root faster)

Immediately place your new cuttings in water. Don’t wait or the clone may die!

The longer you wait after cutting before putting the stem in the water, the more likely air will get in the stem. Air in the stem causes the clone to immediately droop and start dying. That’s why the new cutting must be put in water immediately (just like when cutting flowers or roses for a vase).

Note: If using cloning gel or powdery, quickly dip the end of the stem first then place in water. Some growers dip in gel first, then powder, then into the water.

Some growers trim the edges of their leaves, especially big leaves. This is because the cutting has trouble getting enough water to the leaves without any roots. That’s why it’s also a good idea to trim leaves if it’s very dry where you live (the leaves evaporate water quickly in dry air, and the plant can’t keep up). It can also help to raise the humidity or use a dome to keep more moisture in the air around clones.

Trim the ends of leaves if they’re big, or if the air is dry (under 30% RH) where you live. Otherwise, feel free to leave them alone.

Step 3 – Place new cuttings in a warm bright spot to make roots

WARNING: Make sure cuttings get at least 16+ hours of light per day or they will start flowering (making buds). Even a small lightbulb is good, but it should be kept very close to the clones.

I have a sunny window that gets really warm, and that’s where I like to put the new cuttings. For the first two days, I leave the blinds mostly closed so they’re getting filtered light. After two days I’ll open the blinds and the window so they’re getting direct sunlight for part of the day.

Keep clones warm and humid. Roots form much slower if the air is cool or dry.
Give filtered light for 2 days at first so they have time to adjust
Then move cuttings to a bright spot with direct-but-not-intense light (for example in a sunny window or under a fluorescent grow light)
Maintain water levels. If you notice the water level getting low, gently top off with plain water by pouring water down the sides of the inside of the cup.
Give plants artificial light (like a light bulb kept very close) after the sun goes down too, for a total of 16+ hours of light a day (to prevent plants from flowering)

Should I change the water or just leave it alone? Some growers change the water every day when cloning in a cup to help oxygenate the water, but I personally don’t do that and I’ve never had a problem getting roots to form.

This sunny window is my favorite spot for cup cloning. I angled the blinds so these newly-cut clones get filtered light for a few days before getting full sun. Make sure plants get 16+ hours of light a day to prevent plants from flowering (a light bulb kept close is usually enough after the sun goes out).

Step 4 – Roots typically form within 2-4 weeks

If you’ve followed all the directions here, your cuttings should stay upright and healthy-looking the whole time. After about 2 weeks you may start seeing roots on some plants.

Plant roots look like little nubs at first

They soon develop into more recognizable roots

It’s normal if you notice the bottom of your stems turn brown. That’s just part of the process.

Different cannabis strains/plants root faster than others.

I had an Ocean Fruit plant where every single cutting rooted within 10-12 days. That plant apparently loves being cloned via this method. However, certain plants/strains are just harder to clone than others. I had a Durban Poison plant that took 4 weeks before its cuttings started making roots. All the other plants had rooted all their clones before the first Durban Poison clone made roots. So if your clones are taking a long time to root, it may have nothing to do with you.

Usually some clones have roots within 2-3 weeks. However, it’s normal for some cuttings to take longer than others even from the same plant. You may have some cuttings show roots at week 2, while others from the same plant show their first roots in week 4. It’s a matter of patience. I personally like taking many more clones than needed so I can keep the ones that root first. Those tend to be the fastest-growing plants anyway.

Pay attention to your clones! I completely forgot about these and when I checked on them the roots were grown together and almost all the water was gone!

If your roots grow together, they often can be untangled. Treat them as if you’re gently untangling a knot in someone’s hair. Tug softly and slowly on first one strand, then the others, giving the strands time to unravel and separate from each other. Don’t pull hard or they’ll break!

Now that you have rooted clones, it’s time to install them into their next home.

Not sure whether to put your newly rooted clones in soil, coco, or hydro?

These clones can be used with any grow medium including hydroponics. Once the cuttings have made roots, you install them in your grow medium or hydro reservoir and start treating them like small plants. If you’re looking for a suggestion on the best grow medium for beginners, I’ve had consistently great results with both Coco Loco (soil-based) and Mother Earth Coco + Perlite mix (soilless).

How to Plant Your Rooted Clones in Soil or Coco

1.) Fill your cup half full (or make a 4-5″ deep hole wherever you plan to plant your clone)

2.) Add a little water to the grow medium until it is wet but not soaking, then press down slightly to make a small divet or hole for your roots to fit inside.

When planting your newly rooted clone into a grow medium, you basically want to wet the potting mix first and press down to make a slide indent for your roots.

3.) Gently place your root into the indent you created. If the root is long, you may need to wrap it around in a circle. Avoid using any force, but the roots are pretty flexible.

Having an indent will help keep your roots from touching the sides by giving you an outside “edge” to wrap your roots inside.

If the root is very long, you may need to wrap the root a lot or get creative. Just try to do your best! Once they already have a lot of roots, clones are surprisingly resilient.

If you’re worried about breaking the root, add extra water to the grow medium to make it softer.

4.) Fill the rest of the cup with soil and give a thorough watering.

Try to keep the clone in the middle and upright, but if it’s a little crooked it’s okay. Once the plant is a bit bigger you likely won’t be able to notice.

Try to hold the stem steady in the middle as you fill the cup with soil or coco

Fill to almost the top of the cup with potting mix and then add more water until moist all the way through

5.) Make sure extra water can drain out (plants love good drainage!)

Don’t forget to cut holes out of the bottom so any extra water can drain out. Roots like it wet but not soaking.

I used scissors to cut slits around the edges of the bottom of this cup in order to let any excess water drain out

6.) Give gentle light at first. I leave them in the filtered light of a west-facing window. If you put them under direct light immediately, they can droop or wilt. Once they’ve acclimated to their new home for a day or two and still look happy and healthy, you should be able to start giving them direct light. Within a week it should be growing fast and happy.

7.) Enjoy your new plants!

How to Plant Your Rooted Clones in Hydroponics

Placing these rooted clones in hydroponics is simple and quick. You could plant your clone directly in the clay pebbles, but the following system makes it a bit easier. You probably already have seedling plugs in your grow room if you’re growing with hydroponics.

1.) Get a seedling plug such as Rapid Rooters (or whatever plugs you typically use with your system).

This will be used to hold your clone and keep it anchored where you want.

Any seedling plugs will work to install your clone, but I personally like Rapid Rooters for hydroponic setups

2.) Cut the plug open lengthwise

Take your seedling plug and cut it open lengthwise.

3.) Wrap the plug around the stem of your rooted clone.

Wrap the plug around the stem. This supports the stem so it’s stable and easier to install into a hydroponic system

4.) Install the plug into your hydroponic system just like you normally would. Thread the roots through the bottom holes of your net pot (or cut a hole in your net pot for the roots if they’re too big) and fill in the rest of the way with hydroton to hold seedling in place.

Make sure there is at least an inch of air underneath the very bottom of the stem. You don’t want the water level coming up to the actual stem or it tends to get mushy and hurt the plant (same with seed-grown plants).

Whenever growing cannabis in hydro, always give roots some air to breathe before they touch the water. Oxygen makes the plants grow faster and helps prevent root problems.

As long as you have lots of bubbles in your reservoir, you should have enough water splashing up on the roots that they stay moist even though they’re above the water line. The roots will grow longer until they’re actually dangling in the water, and that’s when clones really take off!

Learn more about growing in hydroponics

Once the roots hit the reservoir your plants will take off!

Hydro tip: Don’t disturb the roots because you enjoy checking on them.

Young cannabis roots find their “spot” in the water and are susceptible to root rot if you move them too much (like the above picture).

If possible, try to always check the roots through a port so you don’t disturb them. If you do disturb the roots, pay close attention to make sure the roots don’t get twisted or tangles by the bubbles. Baby roots want to be left alone so they can roam free and find their personal spot.

One plant roots are a bit thicker, they can’t get twisted anymore. At that point, your thickened cannabis plant roots are remarkably tough.

Established cannabis roots in hydro are tough.

From then on, hydro may be the easiest cannabis grow style.

Learn how to grow cannabis in hydro.

Easy-to-Clone Cannabis Strains

These cannabis strains tend to clone easier than average, though every plant is different.

Medium Potency Strains

These strains make about 15-20% THC. That’s a lot stronger than weed from 20 years ago, but if you’re getting high-potency strains at a dispensary in California, these will feel about medium strength. I like medium potency buds in joints or a long smoking session with friends.

Blue Dream – Most of the true “classic” photoperiod strains are great at cloning. It’s clone-friendly genetics that tend to proliferate so widely. I like this Seed Supreme version of Blue Dream. When I grew it, the Blue Dream was the highest yielding plant in the tent. Plants tend to grow fast and get big. Buds smell sweet and nice. Buzz is classic and long-lasting.
Panama – A great choice that produces well outdoors and smells great. Easy to clone, easy to grow, thrives in the heat, loves lots of sun. Plants need a longer grow season, so not the best choice if it gets cold or rainy early in the autumn where you live.
Northern Lights – A low-odor strain that is ready to harvest faster than most other strains, indoors or out. Big buds, easy to grow, tends to stay short. If you want a quick, stealthy harvest that doesn’t take a lot of work or care, Northern Lights is made for that. Performs well outdoors in cooler climates.

Northern Lights – Easy to clone, low smell, big buds.

High Potency Strains

These strains make up to 30%% THC. The buds effects feel strong to most cannabis enthusiasts. Great for edibles, tinctures, and canna caps that work all day.

Godfather OG – This strain can be overwhelming unless you’re experienced with high potency strains. Easy to grow. Loves lots of light. Give it an extra week or two before harvesting if you want to hit maximum THC potency and yields.
Black Cat Kush – This strain tends to thrive indoors and out, with delicious smell, beautiful bud structure, and strong effects. Some of the plants grow green buds, while others grow dark purple buds that can look almost black after drying.
Hash Burger – A trendy new strain that has it all: high THC, easy to grow, unique smell, above average yields. And easy to clone.

A closeup of Godfather OG buds by Harold

A Godfather OG harvest by Dane.

If you’re in a hurry to get clones right away, learn how to buy cannabis clones directly online.

About Nebula Haze & GrowWeedEasy.com

GrowWeedEasy.com was created in 2010 by Nebula Haze and Sirius Fourside to help people around the world learn how to grow great weed at home. Through our free resources, books, and courses, we help growers get better results with simple, step-by-step cannabis growing tutorials. Always real grows and real pictures based on actual home grow experience.

You might like this other “cup based” cannabis content:

Solo cup challenge: big yields in a tiny cup
Portable cup bong review (my favorite stealthy smoking method)

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