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transplanting cannabis before flowering

When To Re-Pot Your Cannabis Plant And Why

The size of a cannabis plant will depend on the size of the pot it is grown in. Cannabis seeds grown in small pots will become small plants and large pots will encourage larger plants. Many growers choose to start their plants off in small pots and move them into larger ones later on.

Repotting plants like this has many benefits for the root ball and general development of a cannabis plant. That said, knowing the best time to transplant can make all the difference if you’re looking to grow a high yielding plant with a robust root ball. To grow the best medical marijuana everything must be taken into consideration, not just the parts of the cannabis plant you can see.

You can get away without repotting as well, but you’ll get better results if you re-pot them into something smaller first!

How Do Cannabis Plant Roots Grow?

A cannabis seed generally starts under ground in complete darkness, its root system will naturally grow into this darkness and start to fan out while growing down. If a root encounters any light or air as it grows, it will “air prune” itself and branch off into different direction. This process is a natural, healthy way to keep the roots in the dark and helps them in their search for nutrients. Air pruning will make the root ball denser as it happens more and more. Ultimately, the root ball will hit the bottom of the pot and start to spiral along the side of the pot.

Air pruning is a process that causes roots to multiply when they come into contact with air. Fabric pots like the one in this picture stimulate air pruning because the roots get more air.

The first root that comes out of a cannabis seed is the tap root, which extends downwards and anchors the cannabis plant into the medium. This helps create the support a cannabis plant needs to grow upwards. The tap root will also be the base from which many smaller roots grow.

The smaller roots that grow from the tap root are called fibrous roots and their job is to search for nutrients and water. Most air pruning occurs in these roots, making them more efficient in their search for nutrients and water. In the same way that you can pinch out or top a cannabis plant, you can make the root zone much denser using only air.

Why Do I Need To Transplant My Cannabis Plant?

As mentioned above, the roots of a cannabis plant will dig themselves down and push through the dark, moist medium searching for nutrients. This way the roots grow into the shape of the pot and eventually become root bound. Plant roots will always end up growing in the same shape as the pot. So whether you’re using a round pot or a square pot, the root zone will still grow to this shape. The only way to prevent root bound and struggling plants, is to transplant them once you are happy with the root ball. Ideally, the root zone is compact but not too dense to breathe.

This picture is a good example of a full, dense root ball. By filling out a root ball this densely you stimulate maximum nutrient absorption and optimal yields! Can you guess which shape the pot was?

A good example is to take a healthy, well rooted cannabis plant grown in a 5 litre pot and to transplant it to a 15 litre pot. Over time the cannabis plant will expand the root zone in every direction to find new nutrients and minerals and fill out its new pot. Starting cannabis seeds off in a 15 litre pot directly may not be as rewarding as it will not stimulate the root ball to become as dense. Another benefit of transplanting is that you actively break the roots apart, encouraging new root growth in every direction.

Re-potting a cannabis plant helps build a dense root ball that uses the entire pot. Without repotting the roots will shoot down and make less efficient use of the medium.

Is A Root Bound Cannabis Plant Always Unhealthy?

When growing medical marijuana from your own home or commercially, there are serious downsides to letting a cannabis plant become root bound. The most important negative effects include small stunted plants, root rot, slow nutrient uptake, under watered plants and low levels of production.

A cannabis plant can remain relatively healthy while being root bound, but will definitely suffer in terms of production. Healthy root bound plants will stop growing at a certain point as they simply can’t make more roots, this also causes water to be used up very rapidly. Using a certain size of pot can be a practical way to keep your cannabis plant at a desired size, but does increase your chances at running into problems.

This Fast Bud Outdoor plant was grown indoor in a 2 liter pot. You can “break all the rules” as long as you know what you’re doing, whether this is the most efficient or practical is a different story though.

If a root zone is so compact that it cannot breathe, it creates the perfect conditions for root rot. This condition causes cannabis plant roots to go from a bright hairy white to a yellowing brown. Root rot is difficult to fix and can easily kill an affected cannabis plant in only a few days. The root zone is the heart of a cannabis plant so an unhealthy root zone will lead to a sick plant and can easily kill freshly germinated cannabis seeds.

If you discover that you are suffering from root rot and see browning of the roots, you can salvage your grow if you get to it in time. You can use hydrogen peroxide to kill the bacteria that have been building up living in your medium thanks to the limited oxygen. After this, make sure your medium dries up properly so that the roots get air. Ensuring your root zone has good aeration and room to breathe will ensure that your cannabis plant stays happy and pathogen free. Root rot is usually caused by overwatering, but if the root ball has truly become too dense to breathe, your cannabis plant definitely needs a bigger pot.

The roots in this picture are not doing well, the brown color is a clear indication of root rot!

When To Re Pot Your Cannabis Plant

Most cannabis growers transplant their crop two or three times before starting the flowering phase. Ideally, a cannabis plant should be transplanted to a pot that is around 3-5 times the size of the previous container. Smaller will have you repotting too often, larger will make the root system much less dense.

The first pot on the left can contain up to 7.5 liters, the one next to it can hold 12L. Transplanting between these two pots would not add enough room to make it worthwhile.

Generally you will want to allow a cannabis plant to grow for around 3 weeks per transplant. The most common moments to transplant are after the seedling stage, during early veg and again a few weeks before flowering. The exact timings and the number of transplantations depend on the duration of the vegetative phase, medium, training and strain. The global instructions in this article will therefore work for virtually every grow, but can obviously be optimized once you’re more familiar with your setup.

You will have to decide the size of their final pot, as well as what medium you will grow in depending on the total amount of medical marijuana you need. Make sure you repot your cannabis plant shortly before switching it to flowering. The reason for this is because you should avoid shocking a cannabis plant during flowering at all costs. Repotting a cannabis plant during flowering will stunt it and can be very detrimental to your harvest. Just like the rest of the cannabis plant, the root zone will be grown and shaped mostly during the vegetative stage.

Most growers like to start their seeds in a coco, peat or rockwool plug, these provide enough room for root development for the first week or two. After the first leaves come out your seedlings will need some more room and food, so it’s time for their first transplant. The first pot is usually smaller then 1 liter in size, some growers like to go as small as 200mL. Let’s say we’re aiming for a 10 liter pot to finish flowering in, in this scenario a 500 mL would be good to start with.

These seedlings have developed their first leaves and are in the process of being transplanted. A 500mL pot filled with hydroton will provide enough room to grow for the next few weeks.

Two to three weeks after its first transplant, your cannabis plant is ready for its second transplant. This is the time it usually takes to develop three or four sets of leaves and the moment its first full sized leaves start to appear. Without transplanting, a young cannabis plant will become root bound and stop growing at some point after these first big leaves are developed. You can tell this is about to happen when you see a sudden burst of growth and the stem becomes thick enough to hold onto gently without snapping it. At this stage, where a seedling has truly become a small plant, it is time for the second re-potting. The second pot should be quite a bit bigger than the first one and should be large enough to last for most of the vegetative stage. A good fit for our root bound plant in the 500mL plastic cup would be at least a 2 liter pot, let’s say we’re using a 2.5 liter pot in this example.

These cannabis plants have developed a few nodes, and have just started making full-sized, 5-fingered leaves. Now that these stocky little ladies have moved past the seedling stage and grown a bit, they’re ready for their next pot.

Before actually completing the vegetative stage, it is time for the third transplant. For many growers, as well as in this example, this will be the final pot in which flowering stage is completed. By moving our cannabis plant from a 2.5 liter to a 10 liter pot, we’ll add plenty of space to grow roots during late veg and early flowering. We like to start flowering two weeks after the final transplant to make sure the cannabis plant will have completely adjusted to its new surroundings. A cannabis plant that has been grown, pruned and transplanted correctly during the vegetative stage will pay off during flowering and yield an enormous amount of medical marijuana.

After a few weeks of vegetative growth these ladies are ready for their final pot. With multiple nodes worth of full sized leaves, you can tell these are mature cannabis plants that are ready to flower

The sizes mentioned here are all based on our preferences and work well for soil and soilless media like coconut coir. The best sizes for you and your setup might be very different, so experiment as much as you can to see what works best for your grows. Make it your goal to be able to feed every 2-3 days throughout the grow without overwatering. If your cannabis plant is in an appropriately sized pot, it will be able to draw all the moisture out of the medium in a few days.

The Final Pot Size

Many medical marijuana growers are under the impression that the roots of a cannabis plant will fill out its pot during flowering. This is true, but the root zone will grow the most in the vegetative state so this is the time to shape them properly. If you want a cannabis plant with an optimal root system during flowering, you have to start by growing dense roots throughout the vegetative phase. Choosing the final pot size should be based on the roots having enough room to settle and then focus on feeding during the blooming phase.

These monster plants were vegged for over 4 months and have packed on more than a pound each during flower. This wouldn’t have been possible without multiple transplants and an enormous final pot.

The final transplant should take place 2 weeks before flowering your cannabis plant. This will allow time for the root zone to expand without becoming root bound for the rest of the cannabis plant life cycle. When flowering is induced, the root zone will continue to grow for the first 3-5 weeks, after which most of its energy will be geared towards developing heavy flower sets of medical marijuana.

We hope this article has been helpful and has increased your toolset for cannabis cultivation. We also hope to have given you some new ideas on how you can grow the best medical marijuana for your personal needs. As always, good luck growing and have fun with your cannabis plant!

Repotting a cannabis plant has many benefits for the root ball and general development. Knowing the best time to transplant can make all the difference.

How And When To Transplant Your Cannabis Plants

Knowing how and when to transplant your cannabis babies can literally tip the scales in your direction when harvest time comes around. Learn everything you need to know about why, when, and how to transplant your cannabis.

How to transplant your cannabis: tips and advice.

  • 1. Why is transplanting your cannabis important?
  • 2. How often do you need to transplant?
  • 3. When to transplant your cannabis
  • 4. How much space does cannabis need?
  • 4.a. Why not plant into the biggest pot?
  • 4.b. What type of pots should I use?
  • 5. How to transplant cannabis
  • 6. Transplanting: step-by-step guide
  • 7. Size of pots indoors and outdoors
  • 8. What about transplanting autoflowers?
  • 9. Understanding Autoflowering Cannabis Plants
  • 10. Can You Transplant Autoflowering Cannabis Seedlings?
  • 11. How Does Transplanting Affect Autoflowering Cannabis Plants?
  • 12. When Is the Best Time to Transplant Autoflowering Cannabis Plants?
  • 13. How to Transplant Autoflowering Cannabis Plants
  • 14. Plan Ahead to Avoid Transplanting
  • 1. Why is transplanting your cannabis important?
  • 2. How often do you need to transplant?
  • 3. When to transplant your cannabis
  • 4. How much space does cannabis need?
  • 4.a. Why not plant into the biggest pot?
  • 4.b. What type of pots should I use?
  • 5. How to transplant cannabis
  • 6. Transplanting: step-by-step guide
  • 7. Size of pots indoors and outdoors
  • 8. What about transplanting autoflowers?
  • 9. Understanding Autoflowering Cannabis Plants
  • 10. Can You Transplant Autoflowering Cannabis Seedlings?
  • 11. How Does Transplanting Affect Autoflowering Cannabis Plants?
  • 12. When Is the Best Time to Transplant Autoflowering Cannabis Plants?
  • 13. How to Transplant Autoflowering Cannabis Plants
  • 14. Plan Ahead to Avoid Transplanting

Healthy roots mean strong plants and fat, resin-jewelled buds on your cannabis. You want everything big—the bigger the better!

Whether you’ve decided to grow in a SOG, a ScrOG, or are keeping things super-simple, no matter what, you should transplant your cannabis into larger pots at least twice. There are, of course, some exceptions to this rule—which we will clear up later down the line—but first, let’s pose an all-important question.

WHY IS TRANSPLANTING YOUR CANNABIS IMPORTANT?

Unlike with hydroponics, growing in a solid medium like soil or coco makes transplanting into bigger pots necessary as your plants grow. Why is that?

As the roots expand into the substrate and seek out nutrients, their network will grow to encompass as much space as possible. When the roots have completely filled out the volume of the pot, running circles around the inside perimeter of the container, growers refer to these plants as “root bound”. Vegetative growth will slow down, ultimately limiting the potential of your yields as well.

By transplanting to bigger pots early on, we can prevent this from happening. Transplanting ensures the roots always have space to grow freely and vigorously.

HOW OFTEN DO YOU NEED TO TRANSPLANT?

Contrary to what we said in the beginning of this article, you don’t technically need to transplant; but you should—especially if you want to max out yield.

Plants grow faster in smaller pots but are more susceptible to overwatering and overfeeding. When you start in small seedling pots or solo cups, the risk of fungus and other growing problems is largely mitigated, but new problems arise once your soon-to-be vegetative plants want to establish a strong root system.

A good way to go about transplanting is to keep your babies in seedling containers until they’ve each developed at least three nodes. At this point, you can transplant your specimens into larger pots until they double in size. Eventually, you’ll want to move your plants to their final, largest containers where they can truly flourish.

Typically, you will transplant a (photoperiod) plant 2–3 times. Re-potting more frequently isn’t recommended as transplanting causes significant stress.

WHEN TO TRANSPLANT YOUR CANNABIS

Let’s run over a list of visual indicators that can help you determine if your plants need to be moved to larger pots!

Size of the plant: If a plant has visibly outgrown the pot, it’s time to transplant. Look to the number of nodes as a guideline.

Speed of growth: If you see your plant’s growth accelerating in a too-small pot, transplant before growth becomes stunted. As a hint, the more fan leaves your plants have, the more they can photosynthesise, and the bigger they will become.

Root development: If plants are rootbound or roots are coming out of the pot, they need to be transplanted.

Problems with watering: Your growing plants are thirsty! If the pot dries out too quickly, it’s likely your ladies need a larger vessel.

Growing problems: If you observe slow growth or a sickly appearance from plants in undersized pots, it could be due to the size of their container.

HOW MUCH SPACE DOES CANNABIS NEED?

In nature, the spacing of plants affects how they grow. When cannabis is grown for industrial purposes, it is planted very close together. The resulting root tangling releases hormones that encourage a tall plant without much side branching. This characteristic has been exploited by humans for a long time to obtain perfect fibres uninterrupted by heavy branching.

When growing marijuana for personal use, however, you generally want to allow each plant more space—not just to encourage branching and robust growth, but to keep plants healthy overall. So, how big should your containers be at each stage of growth?

As a guide to help you utilise your space and time efficiently, here is a list of standard pot sizes alongside the stage of growth they are typically used during. A very reasonable plant can be grown in a 30cm pot as its final container, and an exceptional plant in a

60cm pot. All standard pots are alike in that their diameter at the rim is equal to their depth. A healthy cannabis plant can easily have a canopy three times the diameter of the pot.

For seedlings and young vegging plants

For robust vegging plants

HOW MUCH SPACE DOES CANNABIS NEED?
For seedlings and young
vegging plants
For robust vegging plants Beginning of final pot size
threshold
10cm = 0.5l 25cm = 11l 46cm = 57l
13–15cm = 1l 30cm = 19l 61cm = 95l
18–20cm = 4l 36cm = 26l 76cm = 114l
22cm = 7.5l 41cm = 38l

WHY NOT PLANT INTO THE BIGGEST POT?

This is up to you. However, a large pot with plenty of soil that is yet to be infiltrated by roots poses a risk of waterlogging. This means you need to be careful when watering so as not to support conditions for mould, rot, or any other type of pathogen or infection.

Cannabis likes dry feet, so err on the side of caution. If planting directly in the biggest pot right away, water sparingly during the first week after potting on. Consider that smaller pots are easier to look after, particularly in the early weeks of vegetation. Small pots are also easier to move when tending to, and can be easily rotated for 360° light coverage.

WHAT TYPE OF POTS SHOULD I USE?

Most cannabis growers opt for standard white plastic pots with drainage holes in the bottom. Why white pots? Black or other dark colours will generate heat as the sun beats down, whereas white containers will help the soil stay relatively cool. Alternatively, some growers like to use air pots or fabric pots, which naturally “air-prune” the roots and allow for optimal health and development. For seedlings, growers tend to use plastic solo cups or specially designed seedling pots.

HOW TO TRANSPLANT CANNABIS

The most important rule to keep in mind when transplanting is that transplant shock causes a lot of stress to your plants. Be extremely careful; the less root damage, the better! This is not a process to rush.

Another important factor is cleanliness. Ensure your working area is clean, and wash your hands before you handle your plants. Better yet, wear gloves.

Do not transplant during the day in the bright sun or under an intense grow light. To avoid exposing your roots to undue light, transplant at night.

TRANSPLANTING: STEP-BY-STEP GUIDE

1. When transplanting your seedling, water them 1–2 days before transplanting. The soil should be moist but not wet. For later transplants, a drier soil will help the root ball stick together.

2. Prepare the new pot by filling it with good-quality soil. Don’t fill it all the way up and don’t overpack. Water the new pot. Dig a hole in the centre large enough for the new plant.

3. With your hand, cover the soil in the old pot (with your plant) and carefully flip it over. The plant should stick out between your fingers.

4. Carefully slide out the root ball and remove the old container. If the root ball doesn’t come right out, gently squeeze and pat the sides of the pot to loosen the soil. If still stuck, lay the pot horizontally on the floor and try to slide out the root ball. If it still won’t come out, use a knife and cut around the outer rim of the soil to free it (use this only as a last resort). Do not grab the plant and try to pull it out with force!

5. When the plant is finally freed, keep a hand under the root ball and transfer the plant to its new hole in its new container. Use extra soil and fill in the gaps. Pat down the soil just slightly to keep your plant in place.

6. Lightly water the plant to help it settle into its new home. This is a good time to use a root stimulator. Root stimulators help ease transplant shock and promote root development.

Pro Tips:

• We recommend preparing your new soil with Easy Boost organic plant nutrition. Add about 50–100g Easy Boost per 20l of soil. Easy Boost is an organic fertiliser that provides your plants with food for 10–12 weeks.

• How long does transplant shock last? It depends, but a few days of slow or stunted growth after transplanting is normal. Allow plants to recover for at least two weeks before inducing bloom or carrying out high-stress training methods.

• If plants are looking weak right after transplanting, support them with stakes.

• Sterilise old containers to reuse in the future.

The environmentally friendly RQS fabric pot, complete with proprietary “Aqua Breathe” geotextile layer, lets your plant’s roots breathe for optimal growth.

The environmentally friendly RQS fabric pot, complete with proprietary “Aqua Breathe” geotextile layer, lets your plant’s roots breathe for optimal growth.

SIZE OF POTS INDOORS AND OUTDOORS

When it comes to recommended pot sizes, this will vary based on whether you are growing indoors or outdoors.

Indoors, you’re constrained by the size of your growing area and the number and expected size of your plants. When growing outdoors, there are often fewer limitations.

Outdoors, you could, in principle, grow as large a plant as you want. This ensures the roots of your cannabis can grow extensively for the biggest possible yields. On the other hand, pots that are too big are not optimal either: If the roots can’t fill an oversized pot, you will end up wasting nutrients.

Large and heavy outdoor pots can also be an issue should you need to move them around. Alternatively, if you’re growing in the wild, you can just plant directly in the ground. This way, plants are not limited by pot size and can reach their full potential.

WHAT ABOUT TRANSPLANTING AUTOFLOWERS?

We generally suggest you avoid transplanting autos and instead plant your germinated autoflowering seeds directly into their final pots. Here’s why:

Understanding Autoflowering Cannabis Plants

Autoflowering cannabis strains flower based on age rather than changes in their light cycle. They get this trait from Cannabis ruderalis, a unique cannabis variety native to certain areas of Eastern Europe and Russia.

Hence, whereas photoperiod strains flower once the days get shorter (or you flip their lights from 18/6 to 12/12), autoflowering strains will flower automatically after about four weeks, although this can vary from one strain to another.

Can You Transplant Autoflowering Cannabis Seedlings?

Yes, you can technically transplant an autoflowering cannabis seedling. However, there is a downside to doing so.

When you transplant a photoperiod strain, you’ll typically keep it in veg for an extra week to help the plant recover from the stress of being transplanted. When transplanting an auto, you don’t have that same luxury, and the stress of the transplant will typically have a bigger impact on the plant’s growth and yield.

How Does Transplanting Affect Autoflowering Cannabis Plants?

A plant’s roots are super sensitive. No matter how gentle you are when transplanting, you’re going to cause your plants some stress when moving them into a new pot.

On average, cannabis plants can take up to 7 days to completely overcome that stress, although this can vary depending on the overall health of a plant (healthier plants will take less time to recover).

Because you have no way to compensate for this stress when growing autos, your plants will typically show signs of stunted growth following the transplant, which will ultimately translate into lighter, lower-quality yields.

When Is the Best Time to Transplant Autoflowering Cannabis Plants?

If you must transplant an auto, timing is absolutely crucial to minimise the impact on your yields. Try to transplant your autos once they’ve developed strong roots and at least 4–5 true leaves.

How to Transplant Autoflowering Cannabis Plants

When transplanting an autoflowering cannabis plant, remember to follow these steps to minimise the shock to your plant’s roots.

Equipment

  • A clean work area
  • Gardening or surgical gloves
  • New pot and soil

Prepare Your Plants, Pots, and Work Area

Avoid watering your plants the day you transplant them, as it’ll be easier to remove dry soil from the container. Also, prepare a clean work area where you’ll perform the transplant. A big, clean table works great.

Finally, prepare your plant’s new pot. You may need to fill the bottom of the new pot with some soil to get your plant to the right height. Also, remember to make sure your new pot has drainage holes.

Remove Your Auto From Its Old Pot

To remove a plant from its pot, tip it over and gently push, massage, or slap the bottom and edges of the pot. Don’t pull at your plant’s stem, as you’ll risk damaging or breaking it!

Place Your Auto in Its New Pot

Place your plant inside the new pot and fill it roughly 2cm from the top with soil. Water generously and, if need be, top up with more soil. Keep a close eye on your plant over the next 3–7 days to check how it is recovering from the transplant.

Plan Ahead to Avoid Transplanting

To get the best results when growing autos, we recommend you plant them directly in their final pots. Most auto varieties will do great in 11–12l pots.

While they’re young, avoid overwatering your autoflowers to prevent drowning their small, delicate roots. Instead, mist their leaves regularly. Once they’ve developed a few true leaves, water them as needed.

Read all about how and when to transplant your cannabis plants. We offer some helpful tips and a step-by-step guide to make the process as easy as possible.