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Caring for Cannabis Seedlings

Cannabis seedlings

What is the cannabis seedling stage?

The seedling stage is a transition from a seed to a plant with the most ridged edges per leaf possible. Since the cannabis plant is still immature and delicate at this time, adequate care is vital if you would like to establish the groundwork for a strong mature plant.

Choose the best genetics, mediums and containers

Your level of expertise and ability as a grower, your budget, grow equipment, and whether you are growing inside or outdoors will all play a role in determining which strain is ideal for you.

Grow in bright, well-distributed and slightly acidic soil with a pH range of 6.30–6.5. Perlite is an excellent soil aerator and nutrient retainer, and we suggest applying between 20% and 50% in your medium. To avoid nutrient lockout and improve drainage, you should increase the amount of perlite in your soil as you increase the amount of nutrients you want to feed your plants.

Avoid overwatering or under-watering seedlings by sprinkling water around their stems only after the earth has dried up entirely. In addition, bear in mind that cannabis seedlings, particularly auto-flowering ones, are highly sensitive to nutrients. Avoid planting them in hot (nutrient-rich) soil and wait until they have developed three to four sets of genuine leaves before feeding them.

In terms of choosing containers, your cannabis seedlings need a sterile environment in which to develop. In the same way, overcrowding and under crowding may both be detrimental to your plant.

Choosing the correct container for your germinating seed is an important element of plant care. There has to be enough room for the root system, but not so much room that the roots can’t soak up all the water from their surroundings. To prevent the plant from drowning, ensure the pot contains holes for draining water.

Use the best germination techniques for your cannabis seedlings

Before cannabis sprouts, it requires four things: moisture, warmth and darkness, and patience. Use one of the following methods to germinate your seeds and guarantee that you get healthy seedlings.

  • The use of paper towels
  • Using a glass of water
  • Consider a seedling starter kit

How to plant cannabis seedlings

Fill your container to the rim with garden soil. Don’t overpack. Make a hole approximately 12″ deep with the eraser side down and insert your germinated seeds, root side down, before covering with dirt.

The different cannabis seedling stages

A healthy cannabis seedling in a seed starter may be buried in the earth and covered with a quarter of an inch of dirt. The soil should be moist but not soaked, so don’t overdo it. Some cannabis producers choose to give their young plants a little extra help. It’s a good idea to use long wooden kitchen matches (without the head). Remember, Cannabis seedling care is vital when planting your cannabis.

How to master the cannabis seedling stage

If any of these factors are out of whack, a seedling’s chances of survival are greatly reduced. With a propagator, you can quickly establish the ideal conditions for your seedlings to thrive, ensuring their success.

Cannabis seedling light schedule

So, how much light do cannabis seedlings need? For you to avoid burning seedlings, use HID or LED lamps with low wattage. When seedlings are exposed to too much light, they, too, acquire scorched, crinkled leaves. It is also possible to develop seedlings that are too lean because they lack light.

Cannabis Sprouts
Big grow of cannabis seedlings

For the light schedule for seedlings in the first 10–14 days, use CFL lamps with a blue light spectrum with an 18/6 light cycle to get the greatest grow. You may begin vegging them with powerful HID or LED lights once they have at least 2–3 nodes and robust true leaves.

Temperature and humidity for healthy cannabis seedlings

Temperature and humidity are two of the most critical environmental parameters to maintain while cultivating healthy cannabis plants. Cannabis seedlings may get overly tall if the temperature in their growing environment rises beyond 80 degrees Fahrenheit. (Around 70 degrees Fahrenheit should be the nighttime temperature goal.) Aim for a greater amount of humidity in the growing environment, usually about 70%. Plants can soak in water from the environment without being weighted down by excessive irrigation.

Watering cannabis seedlings

Unless you have selected a soilless mix, feeding or adding nutrients or fertilizer won’t be essential during this time. For the first several days, use a misting bottle to water once or twice daily. According to the weather and humidity, your watering schedule will vary substantially. With time, you can reduce the frequency of watering to once every two to three days. If in doubt, stick your finger in the soil and see if it’s wet. Add water if it’s too dry. Overwatering is the most common cause of early crop failure, which you should take into consideration.

Growing cannabis seedlings outdoors

Outdoor farmers don’t have the luxury of modifying the temperatures or moisture with the click of a button when growing cannabis seedlings. If you’re an outside farmer, who wants the best cannabis seedling growth, you have three choices on how to manage the seedling stage:

  • Most gardeners opt to keep their seedlings inside under CFL lights for the initial two weeks to safeguard them from hazards. Light for cannabis seedlings is vital for perfect growth.
  • Alternatively, you may leave your seedlings outside throughout the day (as long as temps lie continuously between 20–25°C) and transfer them at night to safeguard them from the cold conditions outside.
  • Finally, you may put your seedlings outside indefinitely in a propagator, greenhouse, or polytunnel to give cover and enable you to boost humidity and adjust the temperature significantly. A cannabis plant sprout is pretty satisfying.

Check out our guide for everyone growing cannabis outdoors to master the seedling stage outdoors and more.

Cannabis seedlings problems


The term “damping off” refers to the phenomenon induced by a fungus such as Pythium, Botrytis, and Fusarium. Even though these fungi are capable of being dormant in the soil, they flourish in damp environments. Damping-off may be caused by various factors, the most prevalent of which is excessive watering and high humidity.

Find out the best humidity for growing cannabis and stop your seedlings damping off.

Also, for further information for indoor growers, check out our article on the ideal temp and humidity for a grow tent.

Nutrient problems

Discoloration on a plant’s leaves or stems might be an indication of nutritional deficiency in cannabis plants. Seeds are filled with nutrients to assist your plants in getting through the early phase of their lives. You need to come in and provide your plants with the nutrients needed to grow and blossom correctly when these nutrients run out.

Pests and insects

On cannabis sprouts, toxins and diseases may decimate seedlings in a matter of hours or even minutes. Keeping your seedlings’ surrounding environment clean and at ideal temperatures and humidity levels is critical to avoiding this. Avoid overwatering, and be sure to learn about common cannabis pests so you can identify and cure them before they become a problem.

Cannabis seedlings stretching

For the seedlings to get access to their light source, they bend. If you don’t want your seedlings to grow unusually long, frail stalks, place them beneath CFLs with a blue spectrum 5cm or so above their heads. Do not leave your seedlings in the dark for more than 24 hours after germination. It will cause your seedlings to grow excessively long.

When to transplant cannabis seedlings

Plants should start in a small container. There is a good chance that your seedlings will die because they are too young to take up as much water as the larger plants. When a cannabis plant seedling is no longer small enough, it will need to be transferred. This is when it’s time to transplant your pot seedling because it has developed four sets of leaves or roots entangled and getting out of the pot. Transplanting cannabis seedlings is essential to provide them with more room for growth.

Picture of Taylor Christianson

Taylor Christianson

Taylor is an indoor expert. Through their writing, they offer a masterclass on growing cannabis indoors, maintaining a productive growing environment, and guiding growers through all the stages of growth both indoors and outdoors. Combining multiple fields of expertise allows for Taylor to give in-depth insights into overall cannabis growing. About this Author

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