Seeding Cannabis

How to care for your cannabis seedling When you’re growing cannabis, you want to keep your plants strong and healthy through every stage of the growing process — and that includes the seedling Seedlings are tiny cannabis plants that just entered the world, hoping to develop high-quality buds one day. Check out how to handle these tiny specimens. The seedling stage of the cannabis lifecycle is when it is at its most vulnerable. Learn a few tips in seedling care right here – giving them the strongest start in life.

How to care for your cannabis seedling

When you’re growing cannabis, you want to keep your plants strong and healthy through every stage of the growing process — and that includes the seedling stage.

The seedling stage can be an especially vulnerable time in the growing process. The cannabis seedling is in need of a lot of TLC to grow into a healthy cannabis plant.

In the seedling stage the cannabis seedling is in need of a lot of TLC to grow into a healthy cannabis plant. Photo by: Gina Coleman/Weedmaps

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But what does that TLC look like? What steps do you need to take to support your cannabis seedlings through the seedling stage and as they grow into mature marijuana plants?

Let’s take a deep dive into how to care for your baby marijuana plant so you know exactly how to take care of your growing seedling and make sure it grows into a healthy, mature cannabis plant.

What happens during the seedling stage?

Before we jump into how to care for your cannabis seedling, let’s quickly cover what happens during this grow stage.

The growing process has four key stages: the seed germination stage, the seedling stage, the vegetative stage, and the flowering stage. Once the cannabis seeds germinate and are placed into their growing medium (like a potting mix), they start to root into the soil as the stem grows upward, sprouting two cotyledon leaves, which help the plant absorb light and continue to grow.

As the plant grows, it starts to produce more fan leaves — and those leaves continue to develop the ridged edges that you’ll immediately recognize as the marijuana plant. As more leaves grow, more ridged edges develop until finally, the plant is fully grown with each leaf reaching its maximum number of edges (which can be anywhere from 5 ridges per leaf to upwards of 10).

This stage — moving from germinated cannabis seeds to cannabis plants with the maximum number of ridged edges per leaf — is the seedling stage.

The seedling stage is an incredibly important part of the growing process; because the cannabis plant is still young and fragile, proper care is essential if you want to lay the foundation for a healthy mature plant.

But what does that care look like? What are the key things to know when it comes to how to take care of marijuana seedlings?

Choose the right container

Your cannabis seedling needs space to grow. But too much space and too little space can both create problems for your plant.

If you try to grow your seedling in a container that’s too large, the root system won’t be able to absorb all the water in the soil. If you start growing your seedling in a container that’s too small, the roots won’t have space to extend and will start to wrap around themselves, which will also impact their ability to absorb water.

Choosing the right pot is an essential part of caring for your growing plant. You need a pot that’s going to give the root system space to grow, but not so much space that the roots won’t be able to absorb all the water in the soil. You should also make sure the pot has drainage holes to get rid of any excess water that could overwhelm the plant.

Choosing the right pot is an essential part of caring for your growing plant. Photo by: Gina Coleman/Weedmaps

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Be mindful of how much you water your cannabis seedlings

When it comes to watering your seedlings, you want to give them the water they need to thrive. But too much water can actually have a negative impact on the growth process, so it’s important to be mindful of how much you water your seedlings.

The root system of a seedling isn’t elaborate; the roots are small and don’t need much water to grow. Misting the plants with water once or twice a day should be plenty to give them the hydration they need to grow.

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If you’re not sure how much water is too much water, keep in mind that you want the growing medium (AKA the soil) to be damp and moist — not soaked and oversaturated.

Know the signs of nutrient deficiencies

A nutrient deficiency can cause serious issues for your growing plant, so part of proper care is knowing how to spot the signs of a nutrient deficiency.

Nutrient deficiencies can come from a variety of places. “Hot” potting mixes that contain too many nutrients could cause nutrient toxicity. On the other end of the spectrum, under-watering can cause a deficiency in the key nutrients your plant needs to grow.

Some red flags that signal your seedling may have a deficiency in nutrients (or nutrient toxicity) include:

  • Dark coloring (cannabis seedlings should be a vibrant shade of green)
  • A burned appearance on the tip of the leaves
  • A curling on the tip of the leaves
  • Yellowing leaves

If you notice any of these issues with your plant, it could be the result of too many or too few nutrients. You’ll need to adjust your growing strategy to support your plant’s health.

Choose the right lighting

Like any plant, seedlings need light in order to grow and thrive. But not all light is created equal. If you want your seedling to grow into a healthy cannabis plant, you need to expose it to the right type of light.

If you’re growing your seedlings outdoors, they’ll need to be exposed to as much sunlight as possible. Keep them in the sun from sunrise to sunset; the more sunlight exposure they get, the better.

If you’re growing your seedlings outdoors, they’ll need to be exposed to as much sunlight as possible. Photo by: Gina Coleman/Weedmaps

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But growing your seedlings outdoors can be tricky. Because you can’t control sunlight, there’s no way to ensure your cannabis seedlings are getting the light they need to grow properly. A cloudy day can prevent your seedlings from getting enough light and throw off your entire growth process.

Growing your seedlings indoors with artificial light gives you more control over the process, making it easier to ensure your plants are getting enough light each day. If you’re growing with artificial lights (compact fluorescent lights that emit cooler, blue spectrum light are especially effective), aim to give your plants 18 hours on and six hours off each day.

Keep your environment at the right temperature and humidity

Environmental conditions are essential to growing healthy cannabis seedlings, and some of the most important conditions to control are temperature and humidity.

The temperature in your grow environment shouldn’t exceed 80 degrees Fahrenheit, otherwise the seedlings may grow too tall. (You should also plan on lowering the temperature at night to about 70 degrees Fahrenheit.)

You should also aim to keep humidity in the grow environment at a higher level, typically around 70 percent. That way, the plants can absorb moisture from the environment to develop stronger roots without getting weighed down by over-watering.

Get out there and grow your seedling into a full-grown marijuana plant

Watching your cannabis seeds transform into seedlings is an exciting part of the growth process. And now that you know how to care for your cannabis seedling, you should have everything you need to transform your seedling into a mature, healthy, and flowering cannabis plant.

What Are Cannabis Seedlings?

Seedlings are tiny cannabis plants that just sprouted into the world. After cannabis seeds pop open, the main root, called the taproot, shoots out. When transferred to soil or another growing medium, a green seedling will eventually emerge from the surface. Any cannabis grower can tell you that the moment a seedling rises, it’s a very special and joyous occasion.

All seedlings look virtually the same; it’s impossible to differentiate cannabis strains based on their visual appearance at this stage in the game. In order for cannabis seeds to properly split open during germination, they must be subject to humid conditions. Once the taproot grows long enough, seedlings with two small sets of teardrop-shaped leaves supported by a thin stem will appear. During the rise, the seed husk naturally detaches, however, sometimes it needs to be surgically removed. These tiny “sucker leaves” will mirror each other on top of the seedling, functioning as panels that transform light into energy .

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Afterward, two additional leaves will develop from the middle, resembling a regular cannabis leaf shape. The seedling stage is quite short; it takes around a week or two before the seedlings grow into short plants. The seedling stage is technically part of the vegetative phase, but it’s often considered somewhat separate due to unique requirements.

Seedlings need extra attention because they’re small and very fragile. Mistakes during this stage can be detrimental to the future growth of your plant. Here are some tips and tricks to provide your seedlings with the ultimate care.

The correct container for a cannabis seedling

After the seeds have split, they’re ready to be sown. The container size for your seedlings should be relatively small. They can even be planted in disposable plastic cups. Then, once they rise to the surface and grow for about a week, they should be moved to larger containers. If seedlings are left for a longer period in small containers, the roots will begin to grow around the sides of the container, making the plants “root bound”. This is undesirable because the roots won’t pick up nutrients in the ideal way, and the water might not drain properly.

One must consider that seedlings develop a surprisingly long tap root. Giving them space to grow will allow the seedlings to stabilise and become stronger. The container needs to have a solid drainage system. This can be done by puncturing holes in the plastic cups or by simply purchasing a container with holes at the bottom. This will allow the taproot to dig its environment, pun intended. Outdoor-grown seedlings must be protected from pesky pests.

One could cut and detach the bottom half of a plastic bottle, punch some holes in it, and place it over the seedling. This will allow the sunlight to penetrate, some airflow to enter, and a defensive shield to protect the seedling from enemies. Many growers prefer to place photoperiodic seedlings directly in the container where they’ll finish flowering to reduce the stress created by transplant shock. This is up to the grower to decide; one can achieve great results with both methods. One thing’s for sure, autoflowering varieties shouldn’t be transplanted. They should be directly planted in the container where they’ll finish flowering.

Growing medium for cannabis seedlings

The growing medium quality matters a great deal. Clay-based soil should be avoided because it retains too much water for seedlings, which can lead to various issues. When seedlings are planted in a growing medium that barely retains any water, they can dry out. It’s best to choose a soil with a loose texture, is dark and rich, retains water, and doesn’t get muddy when wet.

It’s crucial to use soil that hasn’t been over-treated with fertilisers, which is called “hot” soil. This can lead to nutrient toxicity for the seeds. Although many growing mediums with fertilisers work great for seedlings, the fertiliser content needs to be on the lower end of the spectrum.

Grow Tip: How To Take Care Of Cannabis Seedlings

It is vital to take proper care of your seedlings if you want to have a successful grow. Here are some of our growing tips to ensure nothing goes wrong.

It is vital to take proper care of your seedlings if you want to have a successful grow. Here are some of our growing tips to ensure nothing goes wrong.

The seedling stage of cannabis growth is easily the most vulnerable your plants will ever be. For this reason, it is more important than ever to know how to look after them properly. If you get it right, you will ensure your budding little beauties will have the best start in life possible, creating a solid foundation for the rest of their lifecycle to grow off of.


In order for a seedling to thrive, it needs a consistent and stable environment. This includes a consistent temperature, humidity and airflow. There is no more efficient or easier way to do this than by using a seed propagator. This inexpensive piece of kit is basically a mini greenhouse, and ensures that your seedlings remain within their own contained environment.

There are a few ways of obtaining a propagator. Firstly, you can create your own. This can be as simple as securing a clear plastic bag over the top of your pot, with a few air holes for ventilation. Alternatively, you can buy a proper propagator. This will usually cost you in the region of €10-40 depending on its features, and will offer a great deal of control over the environment for your seedling. Such features can include thermometers, inbuilt heating, lighting, and controlled airflow. It really all depends on how much you want to spend, and how much control you want over the seedlings.

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Propagator Pro 2

You can check out the propagator we have in our store as an example, but your local gardening centre is also likely to stock something along the same lines as well.

To begin with, you will want to maintain a consistent root area temperature ranging between 19-24 degrees. This will help ensure that all your seedlings develop at the same speed. An easy way to achieve this achieve this is with a seedling heating mat, which can sometimes be included with a propagator, or bought separately.

Once all of your seedling are fully showing out of the soil you can start ‘hardening the off’. This basically means you start gradually acclimatising them to the environment outside of the propagator without causing them to go into shock. This is done by increasing the amount of air holes in a plastic bag each day, or gradually opening the air vents in a propagator to increase airflow.


The next very important thing to consider is lighting. Although HPS lights are great when your cannabis grow is in full swing, they can often be a bit much for seedlings. A great way to start them is with a CFL light. CFL lights do not put out too much heat (unlike HPS lights), meaning they can be put very close to your seedlings without causing any damage, yet at the same time offer a great light coverage. This ability to place your lights in close proximity also stops your seedlings from stretching, as they do not need to try and grow too tall too quickly to reach the light.

In terms of colour bands, seedlings do best under a blue spectrum, so try and find a bulb that focuses on this – cool white and soft white bulbs tend to be the ones, but double check the specifics of the bulb before you buy anything.

Lastly comes lighting schedule. You can subject your seedlings to an 18/6 schedule without any worries. This will cause the healthiest amount of growth.


The last essential piece in seedling care is feeding. You should not need to give your seedlings any additional nutrients. At this stage, they should be able to get everything they need from the soil, and since they are so delicate in this stage of their life, giving them anything extra is likely to cause nutrient burn, and death – so don’t do it!

All you need to think about is watering you cannabis. At this stage, you only need to use plain water. It should ideally be in a pH range of 6.3-6.5, and if you are using tap water, make sure it has been set aside for at least 48 hours before giving it to your cannabis. This allows the chlorine and other chemicals in tap water to evaporate first.

Water your seedlings whenever the soil begins to feel dry to the touch. You do not want it to be constantly moist, as roots grow most efficiently though depletion – meaning that once they have absorbed all of the water in one area, they grow and seek out other areas that may contain water. If roots have a constant supply of water, not only does it increase the chance of root rot, but also removes their drive to grow.

Note: If you are growing in a more advanced medium, such as rock wool, than your seedlings will not have access to the natural nutrients found within soil. You will need to offer nutrients with your water, usually at ¼ the usual strength.

There you have it! It is easy to look after seedlings when you know how. What they need is stability and consistency, as long as you can offer them that, you will be laughing all the way until they are ready to transplant (usually at 10 days after germination).