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How And When To Transplant Cannabis Seedlings

The seedling phase is arguably the most important of the entire cannabis life cycle. Whether you grow from seed or clone, the hands-on part of cultivation begins with seedlings. Transplanting is all important. Get it wrong, and the crop could be lost. Get it right, and grow great ganja with this guide.

Contents:

THE IMPORTANCE OF CARING FOR CANNABIS SEEDLINGS

Post-germination or post-cutting, your bean or sprout needs a place to take root. The prime objective for the cannabis plant during the seedling stage is the development of a healthy root zone. If your seedlings struggle now, it’s likely they may never completely recover, and even more likely they won’t reach their full potential. Worst case scenario, seedlings die off and the grow is over before it’s even started.

THE OPTIMAL CONDITIONS FOR SEEDLINGS

Cannabis seedlings need to be treated delicately. Mind your marijuana like babies. If seedlings need support, prop them up with a toothpick or a cocktail stick and some soft gardening wire.

An 18-6 light schedule is considered the sweet spot by most growers. White light is preferred. The source of light should be CFL, MH, or LED. If you have a sunny windowsill, it can work in a pinch.

Roots grow in the dark. That’s why we advocate 18-6 or 20-4 over a nonstop 24-hour light cycle. High humidity, ideally around 70% RH, and temperatures in the 20–24°C range make for a perfect seedling habitat. A propagator, thermo-hygrometer, and a spray bottle of water are the tools to help you dial it in.

Stretchy or floppy seedling growth can be due to genetics. Often, it’s an indication the grow lamp is positioned too far away from the canopy. A cool white 250W CFL can comfortably hang 15cm above a dozen or more seedlings without scorching leaves.

WHAT’S THE BEST STARTER SUBSTRATE?

The medium must be wet, not waterlogged. An effective wet-dry cycle is the goal. Remember to resist the temptation to overwater. Better to mist plants with a sprayer if you are not sure. Touch the medium to feel how dry it is and keep RH high.

Before we go into the specifics, we need to be clear that starting in one medium and switching to another can be hazardous. Keep it simple and keep it consistent. You can’t start seedlings in soil and transplant later into a DWC bucket.

CUBES, CUPS, AND SMALL CONTAINERS

Rockwool cubes and blocks are made for hydroponic growers. Start your seedling in a small cube and it couldn’t be easier to transplant later. Simply cut a cube-sized chunk out of a larger block and insert. The process can be repeated with minimal stress to plants.

Unfortunately, rockwool is a really bad idea for soil growers, even the smaller sized blocks. Invariably, the block retains more water than the surrounding soil. Green, sludge-like algae growth soon becomes a problem. Sure, sometimes you can get away with the tiny cubes, but why take the risk?

An oxygen-rich medium that drains well is the ideal mix for soil and/or coco growers. Between these two growing styles, there is the most overlap during the seedling stage. Peat or coco cubes are easy to use and relatively inexpensive. Similar to a rockwool block, you can visually monitor root development as the white spaghetti strands protrude from the cube. Growers, both organic and hydro, working with clones report the highest success rates using the cube-sized starter mediums.

Many soil and coco growers use cups or small plastic pots as starter containers, typically, anywhere in size from 0.5–5l. Lightly fertilised soil mixed with perlite or coco coir mixed with 30–50% perlite are the most common blended media for seedlings. So long as the base of the container has plenty of drainage holes and the interior can hold the volume of medium required, it can serve as a starter pot. Don’t be afraid to improvise. Poke a few holes in the base of a paper coffee cup with a pin and it becomes a pot.

WHEN TO TRANSPLANT SEEDLINGS

The right time to transplant your seedlings is just before they outgrow their current container. With cubes, you can see roots poking out telling you it’s time to pot up. When you start with a cup or small pot, you are relying on above-ground cues. Typically, when the set or sets of true leaves of the seedling have spread out to cover the circumference of the container, it’s time. Also, vertical growth will be an obvious indicator.

Don’t wait too long to transplant. Rootbound plants will take time to recover and may be permanently stunted. In general, it takes 7–10 days for a seedling to take root and outgrow small starter pots of 1l or less.

HOW TO TRANSPLANT SEEDLINGS

Cubes are the easiest to work with. Either cut a hole to size in a bigger block, or burrow a hole into the medium with your fingers and insert for a snug fit. Potting up takes a little more finesse. First, don’t fill your large container all the way to the top. Leave room so you can water properly later. If you pack the pot all the way to the top, water will mostly run off and not reach the roots.

Next, make an impression in your large container with another small pot, or the one with the plant in it if you don’t have any others. Make this impression in the medium after you have watered it. This creates a perfect imprint for the transplant.

It’s best to wait until the medium in the small pot is dry before going for a transplant. Wet soil can fall apart in chunks as you fumble with the sopping mud. Now, turn the dry plant upside down, and firmly pat the bottom. Grasp the plant stem from the base and ease the compacted medium out of the container in one piece. Some topsoil will spill, but don’t worry.

Finally, gently slide the plant, roots first, into the large container. Replace the lost topsoil or coco with a handful or two over the top and add a little more water. That’s the secret to stress-free transplanting.

POTTING UP VS BEGINNING WITH BIG POTS

If your final container size is up to 11l, you have the option to sow seeds directly. This is only a viable option when growing from seed. Clones will not take root in such a large container. Initially, seedlings in large pots will grow more slowly than those in smaller containers. After a few weeks of vegetative growth, the difference is negligible.

If you don’t transplant, then you eliminate the risk of transplant shock. But you also limit the potential of your cannabis plants. That being said, a first and final transplant is sometimes the best option for autoflowering strains with a short life cycle.

Unless smaller plants are advantageous due to limited grow space, bigger is always better. Transplanting is not something beginner growers should avoid. The only way to learn is by doing. If you ever want to grow marijuana monsters, you need to master transplanting seedlings.

Transplanting seedlings is a critical stage in the cannabis life cycle. Get your grow off to a great start with our guide to transplanting.

When Do I Transplant Cannabis Plants?

Why Should I Transplant My Cannabis Plants?

There are advantages to transplanting your marijuana, and this transplant guide and tutorial will teach you when and how to transplant your pot plants perfectly every time. But why should growers transplant their weed plants in the first place? Why not just plant them in their final container from the beginning? The reason is that a proper transplanting regimen actually makes your plants grow faster in the vegetative stage!

Transplanting Young Cannabis Plants At The Right Time Makes Them Grow Faster!

If you start your cannabis plants in a relatively small container they will grow faster than if you planted your seedlings or clones in a big container. This is because it’s easier for a small cannabis plant roots to get the right mixture of air and water when they’re not waterlogged in a big container.

Small Cannabis Plants Grow Faster in Small Containers

But if you do start small, you need to transfer your plants to bigger containers as they grow to ensure the roots have plenty of room to expand. When roots don’t have enough room, they’ll eventually form a “wall” around the edges of the container. This can cause an array of strange root problems.

If left in a container too long, the cannabis plant will actually become “root-bound.” Think of it as if the roots are choking themselves.The plant roots are unable to effectively get the right ratio of oxygen, water and nutrients, and unless the plant is transplanted, the problem continues to get worse as the roots wrap tighter and tighter. Some growers will even use too-small containers to constrict their cannabis plants on purpose and keep them from getting bigger! So when it comes to transplanting cannabis, you want to make sure you transplant at the right time so your plant roots never run out of room. You’ll actually be hurting their growth if you wait too long to transplant!

A root-bound cannabis plant – transplant your plants before it comes to this!

Root-bound cannabis plants grow very slowly and may even stop growing altogether. In addition to proper transplantation, you can prevent cannabis from getting rootbound by growing plants in smart pots (fabric pots) or air pots since they let air in from the sides. This automatically “prunes” the roots around the edges so they can’t form a wall. Plants don’t get rootbound, and tend to grow faster overall in containers like this compared to regular containers, but they need to watered about twice as often as a similarly sized regular pot since the growing medium is constantly being dried from the sides.

Smart Pots (Fabric Pots) & Air Pots Prevent Cannabis From Becoming Root-Bound

They also make it much harder to overwater your plants. The main drawback is they need to be watered much more often than a regular pot. (learn more about them here)

It is really nice that cannabis plants just plain grow faster in pots like smart pots and air pot. I personally recommend them if you can get a bigger size so you don’t have to water as often. Besides solo cups, fabric pots are the only type of container I use for growing cannabis in soil or coco coir! But I digress…

When a marijuana plant is root-bound, it may display a host of seemingly random symptoms such as drooping and nutrient deficiencies, but usually the main symptom is slow growth.

Root-Bound Cannabis Plant in Solo Cup

Drooping, strange leaf symptoms, yellowing and other cannabis nutrient deficiencies can be caused by a too-small container, like the plant pictured below.

The roots are unable to get the right mixture of air, water and nutrients in a too-small container because the roots are wrapped around the edges. The best (and really only) way to fix up a cannabis plant that has become rootbound is to transplant it to a new, bigger container.

Remember, it is okay to plant your young cannabis in a large container right from the beginning if you want to avoid transplanting your marijuana altogether; just know that they may grow a bit slower for the first few weeks compared to if you started them in something small like a solo cup. If you do want to achieve faster growth rates with transplanting, this tutorial gives you a good general guide to make sure you transplant at just the right time, so your plants never get stressed out, and grow as fast as possible.

There’s nothing wrong with planting seeds directly in a big container! The cannabis just grows a little bit slower at first.

How Can I Tell If My Cannabis Plant Is Rootbound?

It can be hard to know exactly when to transplant your cannabis plants into a new container. Here are some scenarios where you might consider transplanting your plants:

  • Soil is drying out too quickly – When your container is drying out only a day or two after each watering it means your plant is drinking fast and needs more water than your current container can hold
  • Plant is getting root problems – A cannabis plant can start showing root problems when it’s kept in a too-small container or if it’s become root-bound. These root problems can cause the plant to become droopy, or show unexpected leaf symptoms or deficiencies (such as spots or yellowing leaves). Whenever literally everything else is right but you’re still experiencing these problems, it may be a sign you need to transplant.
  • Plant has grown a lot or been in the same container for months. If you’re keeping a mother plant for months, or if a plant has doubled in size in the same container, those are signs you may need to transplant to prevent your plant from getting rootbound.
  • Plant is tipping over from its own weight. When your cannabis plant is much wider and taller than its container, it’s easy to tip over and therefore should be transplanted to a bigger pot that can hold it steady.
  • Plant is just plain too big for container (pics below) – There are some pictures below to give you an idea of what a plant looks like that needs to be transplanted. Some plants are just plain too big for the containers they are in.

Now let me give you a few real-life examples you can use to refer to. The following transplanting pictures should help give you an idea of exactly when to transplant your cannabis plants!

These marijuana plants are ready to be transplanted

This cannabis seedling is ready to transplant – you can transplant a cannabis plant from a solo cup once its leaves reach the edges. Don’t wait much longer than this for a seedling in a solo cup!

This next cannabis seedling is huge for a solo cup – it should have been transplanted weeks ago! The strange curling symptoms are a sign that the roots aren’t happy. Once this plant was transplanted it started growing perfectly again.

Sometimes a rootbound cannabis plant shows strange symptoms that almost look like nutrient deficiencies and/or overwatering, when the real problem is it just needs a bigger container!

This next marijuana plant is also way too big for its solo cup. Although it still looks relatively healthy, notice the yellowing bottom leaves with spots and bluish color. If this plant isn’t transplanted to a bigger container, those leaf symptoms will continue moving up the plant and start causing problems. Additionally, most likely this plant would already be much bigger if its roots weren’t being constrained by the solo cup.

These marijuana plants aren’t showing symptoms yet, but they’re getting too big for their pots and should be transplanted soon, especially before they start flowering!

These cannabis plants are way too big for their containers and they’re starting to show strange leaf symptoms, drooping and curling because roots aren’t getting what they need

When a cannabis plant is much wider than its pot, it should be moved to a bigger container even if it’s not showing signs of being root-bound. Not only will the plant roots love the extra space, your plant won’t be so easy to tip over!

This cannabis plant was not transplanted before it started flowering. Although it was healthy its whole life, in the middle of the flowering stage it started drooping and showing these symptoms, because the plant was rootbound. Although it’s generally not recommended to transplant a marijuana plant in the flowering stage, that’s what was needed to fix up this plant and get to harvest!

Seed to Final Container: When to Transplant

1.) Start seeds or clones in a seedling plug/cube or germination station and wait until you start seeing roots come out the bottom (or skip this step and plant seeds directly in a solo cup).

This grower has waited too long before transplanting to bigger container
(it’s good to transfer once you start seeing roots)

2.) Place young plants in a solo cup with holes in the bottom to allow water to drain freely.

Make sure to cut holes in the bottom of the solo cup first, so water can drain out the bottom easily!

Just dig a small hole and stick the starter cubes directly into the new growing medium.

Allow them to grow a few sets of leaves, until the leaves reach the edges, like this…

Once the leaves have reached the edges of the solo cup, it’s time to transfer to a bigger container to prevent your seedlings from getting rootbound.

3.) Transfer plants to a 1, 2 or 3 gallon pot

Instead of pulling the whole plant out of the container, it’s often easier to just cut away the solo cup when you plan on transplanting. This is one of the advantages of starting in disposable cups – it makes transplanting easy and stress-free.

4.) Transfer again when plants double in height

Plants are ready to transfer again when they have about doubled in height.

They should look something like this…

If you’re growing big plants and your cannabis plants double in size again, you may need to transfer one more time!

5.) Transfer cannabis plants into their final container! That’s it. You’re done with transplanting your weed plants!

Now you just need to worry about taking care of your plants until you’re ready to start flowering/budding. Remember plants will usually double (or even triple) in size from when you first initiate the flowering stage.

Note: You can skip some of the steps in the cannabis transplant guide above. Just make sure you’re careful not to overwater small plants in too-big containers. Once plants start growing vigorously, you don’t need to worry as much about overwatering.

Tips For Easy & Stress-Free Transplanting

  1. Water your cannabis plants 1-2 days before transplanting. This will help the growing medium stay together (since it’s moist), but still slide out easily (since it’s not soaking wet).
  2. Before you get started, fill your new pot with potting mix. Don’t fill the pot to the top, instead leave about 2 extra inches (5 cm). That way you can easily water the plant without all the water running off the sides.
  3. Water this new container of potting mix before you begin the transplant so it’s nice and moist. If you don’t water the new soil first, it can have a hard time absorbing water after the transplant, and your roots won’t like that!
  4. Since you will soon be adding a new plant, you want to dig out a hole in the middle that’s about the size of your old container.
  5. Take your plant, and carefully slide a butter knife inside the container all around the edges to help separate the rootball from the sides of the pot. Avoid grabbing the plant directly by the stem. Try to grab the whole top with a flat hand, and turn the container upside down so you can gently pat the rootball out and catch it with your flat hand. You may have to gently pull the plant out of the container, but go slowly and be gentle!
  6. Plant the rootball directly into the new container, placing it in the hole you dug out earlier. You may need to add some extra soil to ensure a nice flat topsoil.
  7. Gently pat down around the roots, to help press everything together slightly, then water your plant immediately. If you do it right, it won’t stress your plants at all!

Minimize Transplant Shock

The process of transplanting can shock your cannabis plants, especially if you wait too long to transplant.

Learn how to avoid cannabis transplant shock!

You can help avoid causing your cannabis plants stress during transplant by following these principles:

  • Transplant your cannabis plants after their roots have begun to fill container (to help hold all the growing medium together) but before the roots have started wrapping around the edges (plants have become rootbound).​
  • Water your cannabis plants 1-2 days before transplanting. This will help the growing medium stay together (since it’s moist), but still slide out easily (since it’s not soaking wet).
  • It’s better to transfer too early than too late!
  • If the roots haven’t grown all around the sides of the root ball (plant isn’t rootbound), avoid disturbing the roots if possible. There’s no need to shake out dirt, just carefully move entire root ball directly into the next pot.
  • Make sure your plants are in their final container at least 1-2 weeks before you switch them over to the flowering stage, and avoid transplanting plants during the flowering/budding stage if you can since the stress may affect your final yields.
  • If your cannabis plants seem like they are suffering from transplant shock (leaf symptoms, drooping, slowed growth), it can be helpful to use a seaweed kelp extract (often available as a liquid fertilizer) to help your cannabis recover more quickly.
  • If transplanting seems scary, it’s okay to plant your seed or clone in its final destination right at the beginning, just be wary of overwatering until the plant is growing vigorously and has a few sets of leaves. You can increase the amount of oxygen available to your plants by adding extra perlite to loosen the soil and allow water to drain through more easily
  • Water your cannabis properly after they’ve been transplanted for the best results!

If you follow all these steps, you may notice that your plant doesn’t show any signs of stress at all!

What Size Should my Final Container Be?

This depends on what size plant you plan to grow, since bigger plants require bigger containers, while smaller plants grow fastest in a relatively small container. For the best results, you need to match the size of your plant with the size of your container.

A general guide is to have up to 2 gallons per 12″ of height. This isn’t perfect, since plants often grow differently, and some plants are short and wide instead of tall, but this is a good rule of thumb.

So if your final (desired) plant size is…

2-3 gallon container

3-5 gallon container

5-7 gallon container

6-10 gallon container

8-10+ gallon container

Go Bigger If You Need to Spend Time Away From Your Cannabis

However, if you plan on being away from your plant for more than a day or two during the grow, it can’t hurt to go up a size or two. The bigger the container, the less often you need to water. So even if you get slightly slower growth in a too-big container, you will definitely be able to spend more time away from your plants without having to water them!

Did you know that transplanting your cannabis at just the right time will actually make your plants to grow faster? Luckily transplanting is easy with a little planning, and only take a few minutes! ]]>