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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.

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.